{"id":171,"date":"2013-06-09T09:42:32","date_gmt":"2013-06-09T01:42:32","guid":{"rendered":"http:\/\/www.zyuns.com\/?p=171"},"modified":"2015-02-15T20:50:50","modified_gmt":"2015-02-15T12:50:50","slug":"mysql-han-shu-da-quan-ji-yong-fa-shi-li","status":"publish","type":"post","link":"https:\/\/www.siediyer.cn\/?p=171","title":{"rendered":"MySQL\u51fd\u6570\u5927\u5168 \u53ca\u7528\u6cd5\u793a\u4f8b"},"content":{"rendered":"

\u5b57\u7b26\u4e32\u51fd\u6570<\/span><\/p>\n

ASCII(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u7b2c\u4e00\u4e2a\u5b57\u7b26\u7684ASCII\u503c(str\u662f\u7a7a\u4e32\u65f6\u8fd4\u56de0)\u00a0\u00a0
\nmysql> select ASCII(‘2’);\u00a0\u00a0
\n-> 50\u00a0\u00a0
\nmysql> select ASCII(2);\u00a0\u00a0
\n-> 50\u00a0\u00a0
\nmysql> select ASCII(‘dete’);\u00a0\u00a0
\n-> 100\u00a0\u00a0
\n
\nORD(str)\u00a0\u00a0\u00a0
\n\u5982\u679c\u5b57\u7b26\u4e32str\u53e5\u9996\u662f\u5355\u5b57\u8282\u8fd4\u56de\u4e0eASCII()\u51fd\u6570\u8fd4\u56de\u7684\u76f8\u540c\u503c\u3002<\/p>\n


\n\u5982\u679c\u662f\u4e00\u4e2a\u591a\u5b57\u8282\u5b57\u7b26,\u4ee5\u683c\u5f0f\u8fd4\u56de((first byte ASCII code)<\/p>\n

*256+(second byte ASCII code))[*256+third byte ASCII<\/p>\n

code…]\u00a0\u00a0
\nmysql> select ORD(‘2’);\u00a0\u00a0
\n-> 50\u00a0\u00a0
\n\u00a0\u00a0
\nCONV(N,from_base,to_base)\u00a0\u00a0\u00a0
\n\u5bf9\u6570\u5b57N\u8fdb\u5236\u8f6c\u6362,\u5e76\u8f6c\u6362\u4e3a\u5b57\u4e32\u8fd4\u56de(\u4efb\u4f55\u53c2\u6570\u4e3aNULL\u65f6\u8fd4\u56de<\/p>\n

NULL,\u8fdb\u5236\u8303\u56f4\u4e3a2-36\u8fdb\u5236,\u5f53to_base\u662f\u8d1f\u6570\u65f6N\u4f5c\u4e3a\u6709\u7b26\u53f7\u6570\u5426\u5219<\/p>\n

\u4f5c\u65e0\u7b26\u53f7\u6570,CONV\u4ee564\u4f4d\u70b9\u7cbe\u5ea6\u5de5\u4f5c)\u00a0\u00a0
\nmysql> select CONV(“a”,16,2);\u00a0\u00a0
\n-> ‘1010’\u00a0
\nmysql> select CONV(“6E”,18,8);\u00a0\u00a0
\n-> ‘172’\u00a0
\nmysql> select CONV(-17,10,-18);\u00a0\u00a0
\n-> ‘-H’\u00a0
\nmysql> select CONV(10+”10″+’10’+0xa,10,10);\u00a0\u00a0
\n-> ’40’\u00a0
\n\u00a0\u00a0
\nBIN(N)\u00a0\u00a0\u00a0
\n\u628aN\u8f6c\u4e3a\u4e8c\u8fdb\u5236\u503c\u5e76\u4ee5\u5b57\u4e32\u8fd4\u56de(N\u662fBIGINT\u6570\u5b57,\u7b49\u4ef7\u4e8eCONV<\/p>\n

(N,10,2))\u00a0\u00a0
\nmysql> select BIN(12);\u00a0\u00a0
\n-> ‘1100’\u00a0
\n
\nOCT(N)\u00a0\u00a0\u00a0
\n\u628aN\u8f6c\u4e3a\u516b\u8fdb\u5236\u503c\u5e76\u4ee5\u5b57\u4e32\u8fd4\u56de(N\u662fBIGINT\u6570\u5b57,\u7b49\u4ef7\u4e8eCONV<\/p>\n

(N,10,8))\u00a0\u00a0
\nmysql> select OCT(12);\u00a0\u00a0
\n-> ’14’\u00a0
\n\u00a0\u00a0
\nHEX(N)\u00a0\u00a0\u00a0
\n\u628aN\u8f6c\u4e3a\u5341\u516d\u8fdb\u5236\u5e76\u4ee5\u5b57\u4e32\u8fd4\u56de(N\u662fBIGINT\u6570\u5b57,\u7b49\u4ef7\u4e8eCONV<\/p>\n

(N,10,16))\u00a0\u00a0
\nmysql> select HEX(255);\u00a0\u00a0
\n-> ‘FF’\u00a0
\n\u00a0\u00a0
\nCHAR(N,…)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u7531\u53c2\u6570N,…\u5bf9\u5e94\u7684ASCII\u4ee3\u7801\u5b57\u7b26\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u4e32(\u53c2\u6570\u662f<\/p>\n

N,…\u662f\u6570\u5b57\u5e8f\u5217,NULL\u503c\u88ab\u8df3\u8fc7)\u00a0\u00a0\u00a0
\nmysql> select CHAR(77,121,83,81,’76’);\u00a0\u00a0
\n-> ‘MySQL’\u00a0
\nmysql> select CHAR(77,77.3,’77.3′);\u00a0\u00a0
\n-> ‘MMM’\u00a0
\n\u00a0\u00a0
\nCONCAT(str1,str2,…)\u00a0\u00a0\u00a0
\n\u628a\u53c2\u6570\u8fde\u6210\u4e00\u4e2a\u957f\u5b57\u7b26\u4e32\u5e76\u8fd4\u56de(\u4efb\u4f55\u53c2\u6570\u662fNULL\u65f6\u8fd4\u56deNULL)\u00a0\u00a0<\/p>\n


\nmysql> select CONCAT(‘My’, ‘S’, ‘QL’);\u00a0\u00a0
\n-> ‘MySQL’\u00a0
\nmysql> select CONCAT(‘My’, NULL, ‘QL’);\u00a0\u00a0
\n-> NULL\u00a0
\nmysql> select CONCAT(14.3);\u00a0\u00a0
\n-> ‘14.3’\u00a0
\n
\nLENGTH(str)\u00a0\u00a0\u00a0
\nOCTET_LENGTH(str)\u00a0\u00a0
\nCHAR_LENGTH(str)\u00a0\u00a0
\nCHARACTER_LENGTH(str)\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u957f\u5ea6(\u5bf9\u4e8e\u591a\u5b57\u8282\u5b57\u7b26CHAR_LENGTH\u4ec5\u8ba1\u7b97\u4e00\u6b21)<\/p>\n


\nmysql> select LENGTH(‘text’);\u00a0\u00a0
\n-> 4\u00a0\u00a0
\nmysql> select OCTET_LENGTH(‘text’);\u00a0\u00a0
\n-> 4\u00a0\u00a0
\n
\nLOCATE(substr,str)\u00a0\u00a0\u00a0
\nPOSITION(substr IN str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32substr\u5728\u5b57\u7b26\u4e32str\u7b2c\u4e00\u6b21\u51fa\u73b0\u7684\u4f4d\u7f6e(str\u4e0d\u5305\u542b<\/p>\n

substr\u65f6\u8fd4\u56de0)\u00a0\u00a0
\nmysql> select LOCATE(‘bar’, ‘foobarbar’);\u00a0\u00a0
\n-> 4\u00a0\u00a0
\nmysql> select LOCATE(‘xbar’, ‘foobar’);\u00a0\u00a0
\n-> 0\u00a0\u00a0
\n\u00a0\u00a0\u00a0
\nLOCATE(substr,str,pos)\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32substr\u5728\u5b57\u7b26\u4e32str\u7684\u7b2cpos\u4e2a\u4f4d\u7f6e\u8d77\u7b2c\u4e00\u6b21\u51fa\u73b0\u7684\u4f4d<\/p>\n

\u7f6e(str\u4e0d\u5305\u542bsubstr\u65f6\u8fd4\u56de0)\u00a0\u00a0
\nmysql> select LOCATE(‘bar’, ‘foobarbar’,5);\u00a0\u00a0
\n-> 7\u00a0\u00a0
\n
\nINSTR(str,substr)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32substr\u5728\u5b57\u7b26\u4e32str\u7b2c\u4e00\u6b21\u51fa\u73b0\u7684\u4f4d\u7f6e(str\u4e0d\u5305\u542b<\/p>\n

substr\u65f6\u8fd4\u56de0)\u00a0\u00a0
\nmysql> select INSTR(‘foobarbar’, ‘bar’);\u00a0\u00a0
\n-> 4\u00a0\u00a0
\nmysql> select INSTR(‘xbar’, ‘foobar’);\u00a0\u00a0
\n-> 0\u00a0\u00a0\u00a0
\n
\nLPAD(str,len,padstr)\u00a0\u00a0\u00a0
\n\u7528\u5b57\u7b26\u4e32padstr\u586b\u8865str\u5de6\u7aef\u76f4\u5230\u5b57\u4e32\u957f\u5ea6\u4e3alen\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select LPAD(‘hi’,4,’??’);\u00a0\u00a0
\n-> ‘??hi’\u00a0
\n\u00a0\u00a0
\nRPAD(str,len,padstr)\u00a0\u00a0\u00a0
\n\u7528\u5b57\u7b26\u4e32padstr\u586b\u8865str\u53f3\u7aef\u76f4\u5230\u5b57\u4e32\u957f\u5ea6\u4e3alen\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select RPAD(‘hi’,5,’?’);\u00a0\u00a0
\n-> ‘hi???’\u00a0
\n
\nLEFT(str,len)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u5de6\u7aeflen\u4e2a\u5b57\u7b26\u00a0\u00a0
\nmysql> select LEFT(‘foobarbar’, 5);\u00a0\u00a0
\n-> ‘fooba’\u00a0
\n
\nRIGHT(str,len)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u53f3\u7aeflen\u4e2a\u5b57\u7b26\u00a0\u00a0\u00a0
\nmysql> select RIGHT(‘foobarbar’, 4);\u00a0\u00a0
\n-> ‘rbar’\u00a0
\n
\nSUBSTRING(str,pos,len)\u00a0\u00a0\u00a0
\nSUBSTRING(str FROM pos FOR len)\u00a0\u00a0\u00a0
\nMID(str,pos,len)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u4f4d\u7f6epos\u8d77len\u4e2a\u5b57\u7b26(\u4f7f\u7528FROM\u7684\u4e11\u964b\u8bed\u6cd5\u662f<\/p>\n

ANSI SQL92\u6807\u51c6)\u00a0\u00a0
\nmysql> select SUBSTRING(‘Quadratically’,5,6);\u00a0\u00a0
\n-> ‘ratica’\u00a0
\n
\nSUBSTRING(str,pos)\u00a0\u00a0\u00a0
\nSUBSTRING(str FROM pos)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u4f4d\u7f6epos\u8d77\u7684\u4e00\u4e2a\u5b50\u4e32\u00a0\u00a0
\nmysql> select SUBSTRING(‘Quadratically’,5);\u00a0\u00a0
\n-> ‘ratically’\u00a0
\nmysql> select SUBSTRING(‘foobarbar’ FROM 4);\u00a0\u00a0
\n-> ‘barbar’\u00a0
\n
\nSUBSTRING_INDEX(str,delim,count)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u4ece\u5b57\u7b26\u4e32str\u7684\u7b2ccount\u4e2a\u51fa\u73b0\u7684\u5206\u9694\u7b26delim\u4e4b\u540e\u7684\u5b50\u4e32<\/p>\n

(count\u4e3a\u6b63\u6570\u65f6\u8fd4\u56de\u5de6\u7aef,\u5426\u5219\u8fd4\u56de\u53f3\u7aef\u5b50\u4e32)\u00a0\u00a0
\nmysql> select SUBSTRING_INDEX(‘www.mysql.com’, ‘.’, 2);\u00a0\u00a0
\n-> ‘www.mysql’\u00a0
\nmysql> select SUBSTRING_INDEX(‘www.mysql.com’, ‘.’, -2);\u00a0\u00a0
\n-> ‘mysql.com’\u00a0
\n
\nLTRIM(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5220\u9664\u4e86\u5de6\u7a7a\u683c\u7684\u5b57\u7b26\u4e32str\u00a0\u00a0
\nmysql> select LTRIM(‘\u00a0 barbar’);\u00a0\u00a0
\n-> ‘barbar’\u00a0
\n
\nRTRIM(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5220\u9664\u4e86\u53f3\u7a7a\u683c\u7684\u5b57\u7b26\u4e32str\u00a0\u00a0
\nmysql> select RTRIM(‘barbar\u00a0\u00a0 ‘);\u00a0\u00a0
\n-> ‘barbar’\u00a0
\n
\nTRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u524d\u7f00\u6216\u540e\u7f00remstr\u88ab\u5220\u9664\u4e86\u7684\u5b57\u7b26\u4e32str(\u4f4d\u7f6e\u53c2\u6570\u9ed8\u8ba4<\/p>\n

BOTH,remstr\u9ed8\u8ba4\u503c\u4e3a\u7a7a\u683c)\u00a0\u00a0
\nmysql> select TRIM(‘\u00a0 bar\u00a0\u00a0 ‘);\u00a0\u00a0
\n-> ‘bar’\u00a0
\nmysql> select TRIM(LEADING ‘x’ FROM ‘xxxbarxxx’);\u00a0\u00a0
\n-> ‘barxxx’\u00a0
\nmysql> select TRIM(BOTH ‘x’ FROM ‘xxxbarxxx’);\u00a0\u00a0
\n-> ‘bar’\u00a0
\nmysql> select TRIM(TRAILING ‘xyz’ FROM ‘barxxyz’);\u00a0\u00a0
\n-> ‘barx’\u00a0
\n
\nSOUNDEX(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56destr\u7684\u4e00\u4e2a\u540c\u97f3\u5b57\u7b26\u4e32(\u542c\u8d77\u6765\u201c\u5927\u81f4\u76f8\u540c\u201d\u5b57\u7b26\u4e32\u6709\u76f8\u540c\u7684<\/p>\n

\u540c\u97f3\u5b57\u7b26\u4e32,\u975e\u6570\u5b57\u5b57\u6bcd\u5b57\u7b26\u88ab\u5ffd\u7565,\u5728A-Z\u5916\u7684\u5b57\u6bcd\u88ab\u5f53\u4f5c\u5143\u97f3)\u00a0\u00a0
\nmysql> select SOUNDEX(‘Hello’);\u00a0\u00a0
\n-> ‘H400’\u00a0
\nmysql> select SOUNDEX(‘Quadratically’);\u00a0\u00a0
\n-> ‘Q36324’\u00a0
\n\u00a0\u00a0
\nSPACE(N)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u7531N\u4e2a\u7a7a\u683c\u5b57\u7b26\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u00a0\u00a0
\nmysql> select SPACE(6);\u00a0\u00a0
\n-> ‘\u00a0\u00a0\u00a0\u00a0\u00a0 ‘\u00a0
\n\u00a0\u00a0
\nREPLACE(str,from_str,to_str)\u00a0\u00a0\u00a0
\n\u7528\u5b57\u7b26\u4e32to_str\u66ff\u6362\u5b57\u7b26\u4e32str\u4e2d\u7684\u5b50\u4e32from_str\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select REPLACE(‘www.mysql.com’, ‘w’, ‘Ww’);\u00a0\u00a0
\n-> ‘WwWwWw.mysql.com’\u00a0
\n
\nREPEAT(str,count)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u7531count\u4e2a\u5b57\u7b26\u4e32str\u8fde\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32(\u4efb\u4f55\u53c2\u6570\u4e3aNULL\u65f6<\/p>\n

\u8fd4\u56deNULL,count<=0\u65f6\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5b57\u7b26\u4e32)\u00a0\u00a0
\nmysql> select REPEAT(‘MySQL’, 3);\u00a0\u00a0
\n-> ‘MySQLMySQLMySQL’\u00a0
\n\u00a0\u00a0
\nREVERSE(str)\u00a0\u00a0\u00a0
\n\u98a0\u5012\u5b57\u7b26\u4e32str\u7684\u5b57\u7b26\u987a\u5e8f\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select REVERSE(‘abc’);\u00a0\u00a0
\n-> ‘cba’\u00a0
\n
\nINSERT(str,pos,len,newstr)\u00a0\u00a0\u00a0
\n\u628a\u5b57\u7b26\u4e32str\u7531\u4f4d\u7f6epos\u8d77len\u4e2a\u5b57\u7b26\u957f\u7684\u5b50\u4e32\u66ff\u6362\u4e3a\u5b57\u7b26\u4e32<\/p>\n

newstr\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select INSERT(‘Quadratic’, 3, 4, ‘What’);\u00a0\u00a0
\n-> ‘QuWhattic’\u00a0
\n
\nELT(N,str1,str2,str3,…)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u7b2cN\u4e2a\u5b57\u7b26\u4e32(N\u5c0f\u4e8e1\u6216\u5927\u4e8e\u53c2\u6570\u4e2a\u6570\u8fd4\u56deNULL)\u00a0\u00a0
\nmysql> select ELT(1, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);\u00a0\u00a0
\n-> ‘ej’\u00a0
\nmysql> select ELT(4, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);\u00a0\u00a0
\n-> ‘foo’\u00a0
\n
\nFIELD(str,str1,str2,str3,…)\u00a0\u00a0\u00a0
\n\u8fd4\u56destr\u7b49\u4e8e\u5176\u540e\u7684\u7b2cN\u4e2a\u5b57\u7b26\u4e32\u7684\u5e8f\u53f7(\u5982\u679cstr\u6ca1\u627e\u5230\u8fd4\u56de0)\u00a0\u00a0
\nmysql> select FIELD(‘ej’, ‘Hej’, ‘ej’, ‘Heja’, ‘hej’,<\/p>\n

‘foo’);\u00a0\u00a0
\n-> 2\u00a0\u00a0
\nmysql> select FIELD(‘fo’, ‘Hej’, ‘ej’, ‘Heja’, ‘hej’,<\/p>\n

‘foo’);\u00a0\u00a0
\n-> 0\u00a0\u00a0
\n
\nFIND_IN_SET(str,strlist)\u00a0\u00a0\u00a0
\n\u8fd4\u56destr\u5728\u5b57\u7b26\u4e32\u96c6strlist\u4e2d\u7684\u5e8f\u53f7(\u4efb\u4f55\u53c2\u6570\u662fNULL\u5219\u8fd4\u56de<\/p>\n

NULL,\u5982\u679cstr\u6ca1\u627e\u5230\u8fd4\u56de0,\u53c2\u65701\u5305\u542b”,”\u65f6\u5de5\u4f5c\u5f02\u5e38)\u00a0\u00a0
\nmysql> SELECT FIND_IN_SET(‘b’,’a,b,c,d’);\u00a0\u00a0
\n-> 2\u00a0\u00a0
\n\u00a0\u00a0
\nMAKE_SET(bits,str1,str2,…)\u00a0\u00a0
\n\u628a\u53c2\u65701\u7684\u6570\u5b57\u8f6c\u4e3a\u4e8c\u8fdb\u5236,\u5047\u5982\u67d0\u4e2a\u4f4d\u7f6e\u7684\u4e8c\u8fdb\u5236\u4f4d\u7b49\u4e8e1,\u5bf9\u5e94<\/p>\n

\u4f4d\u7f6e\u7684\u5b57\u4e32\u9009\u5165\u5b57\u4e32\u96c6\u5e76\u8fd4\u56de(NULL\u4e32\u4e0d\u6dfb\u52a0\u5230\u7ed3\u679c\u4e2d)\u00a0\u00a0
\nmysql> SELECT MAKE_SET(1,’a’,’b’,’c’);\u00a0\u00a0
\n-> ‘a’\u00a0
\nmysql> SELECT MAKE_SET(1 | 4,’hello’,’nice’,’world’);\u00a0\u00a0
\n-> ‘hello,world’\u00a0
\nmysql> SELECT MAKE_SET(0,’a’,’b’,’c’);\u00a0\u00a0
\n-> ”\u00a0
\n
\nEXPORT_SET(bits,on,off,[separator,[number_of_bits]])\u00a0\u00a0\u00a0
\n\u6309bits\u6392\u5217\u5b57\u7b26\u4e32\u96c6,\u53ea\u6709\u5f53\u4f4d\u7b49\u4e8e1\u65f6\u63d2\u5165\u5b57\u4e32on,\u5426\u5219\u63d2\u5165<\/p>\n

off(separator\u9ed8\u8ba4\u503c”,”,number_of_bits\u53c2\u6570\u4f7f\u7528\u65f6\u957f\u5ea6\u4e0d\u8db3\u88650<\/p>\n

\u800c\u8fc7\u957f\u622a\u65ad)\u00a0\u00a0\u00a0
\nmysql> select EXPORT_SET(5,’Y’,’N’,’,’,4)\u00a0\u00a0
\n-> Y,N,Y,N\u00a0\u00a0\u00a0
\n
\nLCASE(str)\u00a0\u00a0
\nLOWER(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5c0f\u5199\u7684\u5b57\u7b26\u4e32str\u00a0\u00a0
\nmysql> select LCASE(‘QUADRATICALLY’);\u00a0\u00a0
\n-> ‘quadratically’\u00a0
\n\u00a0\u00a0
\nUCASE(str)\u00a0\u00a0\u00a0
\nUPPER(str)\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5927\u5199\u7684\u5b57\u7b26\u4e32str\u00a0\u00a0
\nmysql> select UCASE(‘quadratically’);\u00a0\u00a0
\n-> ‘QUADRATICALLY’\u00a0
\n
\nLOAD_FILE(file_name)\u00a0\u00a0\u00a0
\n\u8bfb\u5165\u6587\u4ef6\u5e76\u4e14\u4f5c\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32\u8fd4\u56de\u6587\u4ef6\u5185\u5bb9(\u6587\u4ef6\u65e0\u6cd5\u627e\u5230,\u8def\u5f84<\/p>\n

\u4e0d\u5b8c\u6574,\u6ca1\u6709\u6743\u9650,\u957f\u5ea6\u5927\u4e8emax_allowed_packet\u4f1a\u8fd4\u56deNULL)\u00a0\u00a0
\nmysql> UPDATE table_name SET blob_column=LOAD_FILE<\/p>\n

(“\/tmp\/picture”) WHERE id=1;\u00a0\u00a0
\n
\n\u6570\u5b66\u51fd\u6570<\/span><\/p>\n

ABS(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u7edd\u5bf9\u503c\u00a0\u00a0
\nmysql> select ABS(2);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\nmysql> select ABS(-32);\u00a0\u00a0\u00a0\u00a0
\n-> 32\u00a0\u00a0\u00a0\u00a0
\n\u00a0\u00a0
\nSIGN(N)\u00a0\u00a0
\n\u8fd4\u56de\u53c2\u6570\u7684\u7b26\u53f7(\u4e3a-1\u30010\u62161)\u00a0\u00a0
\nmysql> select SIGN(-32);\u00a0\u00a0\u00a0\u00a0
\n-> -1\u00a0\u00a0\u00a0\u00a0
\nmysql> select SIGN(0);\u00a0\u00a0\u00a0\u00a0
\n-> 0\u00a0\u00a0\u00a0\u00a0
\nmysql> select SIGN(234);\u00a0\u00a0\u00a0\u00a0
\n-> 1\u00a0\u00a0\u00a0\u00a0
\n
\nMOD(N,M)\u00a0\u00a0\u00a0\u00a0
\n\u53d6\u6a21\u8fd0\u7b97,\u8fd4\u56deN\u88abM\u9664\u7684\u4f59\u6570(\u540c%\u64cd\u4f5c\u7b26)\u00a0\u00a0\u00a0\u00a0
\nmysql> select MOD(234, 10);\u00a0\u00a0\u00a0\u00a0
\n-> 4\u00a0\u00a0\u00a0\u00a0
\nmysql> select 234 % 10;\u00a0\u00a0\u00a0\u00a0
\n-> 4\u00a0\u00a0\u00a0\u00a0
\nmysql> select MOD(29,9);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\n
\nFLOOR(N)\u00a0\u00a0
\n\u8fd4\u56de\u4e0d\u5927\u4e8eN\u7684\u6700\u5927\u6574\u6570\u503c\u00a0\u00a0
\nmysql> select FLOOR(1.23);\u00a0\u00a0\u00a0\u00a0
\n-> 1\u00a0\u00a0\u00a0\u00a0
\nmysql> select FLOOR(-1.23);\u00a0\u00a0\u00a0\u00a0
\n-> -2\u00a0\u00a0\u00a0\u00a0
\n
\nCEILING(N)\u00a0\u00a0
\n\u8fd4\u56de\u4e0d\u5c0f\u4e8eN\u7684\u6700\u5c0f\u6574\u6570\u503c\u00a0\u00a0
\nmysql> select CEILING(1.23);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\nmysql> select CEILING(-1.23);\u00a0\u00a0\u00a0\u00a0
\n-> -1\u00a0\u00a0\u00a0\u00a0
\n
\nROUND(N,D)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u56db\u820d\u4e94\u5165\u503c,\u4fdd\u7559D\u4f4d\u5c0f\u6570(D\u7684\u9ed8\u8ba4\u503c\u4e3a0)\u00a0\u00a0
\nmysql> select ROUND(-1.23);\u00a0\u00a0\u00a0\u00a0
\n-> -1\u00a0\u00a0\u00a0\u00a0
\nmysql> select ROUND(-1.58);\u00a0\u00a0\u00a0\u00a0
\n-> -2\u00a0\u00a0\u00a0\u00a0
\nmysql> select ROUND(1.58);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\nmysql> select ROUND(1.298, 1);\u00a0\u00a0\u00a0\u00a0
\n-> 1.3\u00a0\u00a0\u00a0\u00a0
\nmysql> select ROUND(1.298, 0);\u00a0\u00a0\u00a0\u00a0
\n-> 1\u00a0\u00a0\u00a0\u00a0
\n
\nEXP(N)\u00a0\u00a0
\n\u8fd4\u56de\u503ce\u7684N\u6b21\u65b9(\u81ea\u7136\u5bf9\u6570\u7684\u5e95)\u00a0\u00a0
\nmysql> select EXP(2);\u00a0\u00a0\u00a0\u00a0
\n-> 7.389056\u00a0\u00a0\u00a0\u00a0
\nmysql> select EXP(-2);\u00a0\u00a0\u00a0\u00a0
\n-> 0.135335\u00a0\u00a0\u00a0\u00a0
\n
\nLOG(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u81ea\u7136\u5bf9\u6570\u00a0\u00a0
\nmysql> select LOG(2);\u00a0\u00a0\u00a0\u00a0
\n-> 0.693147\u00a0\u00a0\u00a0\u00a0
\nmysql> select LOG(-2);\u00a0\u00a0\u00a0\u00a0
\n-> NULL\u00a0\u00a0\u00a0\u00a0
\n
\nLOG10(N)\u00a0\u00a0
\n\u8fd4\u56deN\u4ee510\u4e3a\u5e95\u7684\u5bf9\u6570\u00a0\u00a0
\nmysql> select LOG10(2);\u00a0\u00a0\u00a0\u00a0
\n-> 0.301030\u00a0\u00a0\u00a0\u00a0
\nmysql> select LOG10(100);\u00a0\u00a0\u00a0\u00a0
\n-> 2.000000\u00a0\u00a0\u00a0\u00a0
\nmysql> select LOG10(-100);\u00a0\u00a0\u00a0\u00a0
\n-> NULL\u00a0\u00a0\u00a0\u00a0
\n
\nPOW(X,Y)\u00a0\u00a0\u00a0\u00a0
\nPOWER(X,Y)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u503cX\u7684Y\u6b21\u5e42\u00a0\u00a0
\nmysql> select POW(2,2);\u00a0\u00a0\u00a0\u00a0
\n-> 4.000000\u00a0\u00a0\u00a0\u00a0
\nmysql> select POW(2,-2);\u00a0\u00a0\u00a0\u00a0
\n-> 0.250000\u00a0\u00a0
\n
\nSQRT(N)\u00a0\u00a0
\n\u8fd4\u56de\u975e\u8d1f\u6570N\u7684\u5e73\u65b9\u6839\u00a0\u00a0
\nmysql> select SQRT(4);\u00a0\u00a0\u00a0\u00a0
\n-> 2.000000\u00a0\u00a0\u00a0\u00a0
\nmysql> select SQRT(20);\u00a0\u00a0\u00a0\u00a0
\n-> 4.472136\u00a0\u00a0\u00a0\u00a0
\n
\nPI()\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5706\u5468\u7387\u00a0\u00a0\u00a0
\nmysql> select PI();\u00a0\u00a0\u00a0\u00a0
\n-> 3.141593\u00a0\u00a0\u00a0\u00a0
\n
\nCOS(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u4f59\u5f26\u503c\u00a0\u00a0
\nmysql> select COS(PI());\u00a0\u00a0
\n-> -1.000000\u00a0\u00a0\u00a0\u00a0
\n
\nSIN(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u6b63\u5f26\u503c\u00a0\u00a0\u00a0
\nmysql> select SIN(PI());\u00a0\u00a0\u00a0\u00a0
\n-> 0.000000\u00a0\u00a0\u00a0\u00a0
\n
\nTAN(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u6b63\u5207\u503c\u00a0\u00a0
\nmysql> select TAN(PI()+1);\u00a0\u00a0\u00a0\u00a0
\n-> 1.557408\u00a0\u00a0\u00a0\u00a0
\n
\nACOS(N)\u00a0\u00a0
\n\u8fd4\u56deN\u53cd\u4f59\u5f26(N\u662f\u4f59\u5f26\u503c,\u5728-1\u52301\u7684\u8303\u56f4,\u5426\u5219\u8fd4\u56deNULL)\u00a0\u00a0
\nmysql> select ACOS(1);\u00a0\u00a0\u00a0\u00a0
\n-> 0.000000\u00a0\u00a0\u00a0\u00a0
\nmysql> select ACOS(1.0001);\u00a0\u00a0\u00a0\u00a0
\n-> NULL\u00a0\u00a0\u00a0\u00a0
\nmysql> select ACOS(0);\u00a0\u00a0\u00a0\u00a0
\n-> 1.570796\u00a0\u00a0\u00a0\u00a0
\n
\nASIN(N)\u00a0\u00a0
\n\u8fd4\u56deN\u53cd\u6b63\u5f26\u503c\u00a0\u00a0
\nmysql> select ASIN(0.2);\u00a0\u00a0\u00a0\u00a0
\n-> 0.201358\u00a0\u00a0\u00a0\u00a0
\nmysql> select ASIN(‘foo’);\u00a0\u00a0\u00a0\u00a0
\n-> 0.000000\u00a0\u00a0\u00a0\u00a0
\n
\nATAN(N)\u00a0\u00a0
\n\u8fd4\u56deN\u7684\u53cd\u6b63\u5207\u503c\u00a0\u00a0
\nmysql> select ATAN(2);\u00a0\u00a0\u00a0\u00a0
\n-> 1.107149\u00a0\u00a0\u00a0\u00a0
\nmysql> select ATAN(-2);\u00a0\u00a0\u00a0\u00a0
\n-> -1.107149\u00a0\u00a0\u00a0\u00a0
\nATAN2(X,Y)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de2\u4e2a\u53d8\u91cfX\u548cY\u7684\u53cd\u6b63\u5207(\u7c7b\u4f3cY\/X\u7684\u53cd\u6b63\u5207,\u7b26\u53f7\u51b3\u5b9a\u8c61\u9650)\u00a0\u00a0
\nmysql> select ATAN(-2,2);\u00a0\u00a0\u00a0\u00a0
\n-> -0.785398\u00a0\u00a0\u00a0\u00a0
\nmysql> select ATAN(PI(),0);\u00a0\u00a0\u00a0\u00a0
\n-> 1.570796\u00a0\u00a0\u00a0\u00a0
\n
\nCOT(N)\u00a0\u00a0
\n\u8fd4\u56deX\u7684\u4f59\u5207\u00a0\u00a0
\nmysql> select COT(12);\u00a0\u00a0\u00a0\u00a0
\n-> -1.57267341\u00a0\u00a0\u00a0\u00a0
\nmysql> select COT(0);\u00a0\u00a0\u00a0\u00a0
\n-> NULL\u00a0\u00a0\u00a0\u00a0
\n
\nRAND()\u00a0\u00a0
\nRAND(N)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5728\u8303\u56f40\u52301.0\u5185\u7684\u968f\u673a\u6d6e\u70b9\u503c(\u53ef\u4ee5\u4f7f\u7528\u6570\u5b57N\u4f5c\u4e3a\u521d\u59cb\u503c)\u00a0<\/p>\n


\nmysql> select RAND();\u00a0\u00a0\u00a0\u00a0
\n-> 0.5925\u00a0\u00a0\u00a0\u00a0
\nmysql> select RAND(20);\u00a0\u00a0\u00a0\u00a0
\n-> 0.1811\u00a0\u00a0\u00a0\u00a0
\nmysql> select RAND(20);\u00a0\u00a0\u00a0\u00a0
\n-> 0.1811\u00a0\u00a0\u00a0\u00a0
\nmysql> select RAND();\u00a0\u00a0\u00a0\u00a0
\n-> 0.2079\u00a0\u00a0\u00a0\u00a0
\nmysql> select RAND();\u00a0\u00a0\u00a0\u00a0
\n-> 0.7888\u00a0\u00a0\u00a0\u00a0
\n
\nDEGREES(N)\u00a0\u00a0
\n\u628aN\u4ece\u5f27\u5ea6\u53d8\u6362\u4e3a\u89d2\u5ea6\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select DEGREES(PI());\u00a0\u00a0\u00a0\u00a0
\n-> 180.000000\u00a0\u00a0\u00a0\u00a0
\n
\nRADIANS(N)\u00a0\u00a0
\n\u628aN\u4ece\u89d2\u5ea6\u53d8\u6362\u4e3a\u5f27\u5ea6\u5e76\u8fd4\u56de\u00a0\u00a0\u00a0
\nmysql> select RADIANS(90);\u00a0\u00a0\u00a0\u00a0
\n-> 1.570796\u00a0\u00a0\u00a0\u00a0
\n
\nTRUNCATE(N,D)\u00a0\u00a0\u00a0\u00a0
\n\u4fdd\u7559\u6570\u5b57N\u7684D\u4f4d\u5c0f\u6570\u5e76\u8fd4\u56de\u00a0\u00a0
\nmysql> select TRUNCATE(1.223,1);\u00a0\u00a0\u00a0\u00a0
\n-> 1.2\u00a0\u00a0\u00a0\u00a0
\nmysql> select TRUNCATE(1.999,1);\u00a0\u00a0\u00a0\u00a0
\n-> 1.9\u00a0\u00a0\u00a0\u00a0
\nmysql> select TRUNCATE(1.999,0);\u00a0\u00a0\u00a0\u00a0
\n-> 1\u00a0\u00a0\u00a0\u00a0
\n
\nLEAST(X,Y,…)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u6700\u5c0f\u503c(\u5982\u679c\u8fd4\u56de\u503c\u88ab\u7528\u5728\u6574\u6570(\u5b9e\u6570\u6216\u5927\u5c0f\u654f\u611f\u5b57\u4e32)\u4e0a\u4e0b<\/p>\n

\u6587\u6216\u6240\u6709\u53c2\u6570\u90fd\u662f\u6574\u6570(\u5b9e\u6570\u6216\u5927\u5c0f\u654f\u611f\u5b57\u4e32)\u5219\u4ed6\u4eec\u4f5c\u4e3a\u6574\u6570(\u5b9e<\/p>\n

\u6570\u6216\u5927\u5c0f\u654f\u611f\u5b57\u4e32)\u6bd4\u8f83,\u5426\u5219\u6309\u5ffd\u7565\u5927\u5c0f\u5199\u7684\u5b57\u7b26\u4e32\u88ab\u6bd4\u8f83)\u00a0\u00a0
\nmysql> select LEAST(2,0);\u00a0\u00a0\u00a0\u00a0
\n-> 0\u00a0\u00a0\u00a0\u00a0
\nmysql> select LEAST(34.0,3.0,5.0,767.0);\u00a0\u00a0\u00a0\u00a0
\n-> 3.0\u00a0\u00a0\u00a0\u00a0
\nmysql> select LEAST(“B”,”A”,”C”);\u00a0\u00a0\u00a0\u00a0
\n-> “A”\u00a0\u00a0\u00a0\u00a0
\n
\nGREATEST(X,Y,…)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u6700\u5927\u503c(\u5176\u4f59\u540cLEAST())\u00a0\u00a0
\nmysql> select GREATEST(2,0);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\nmysql> select GREATEST(34.0,3.0,5.0,767.0);\u00a0\u00a0\u00a0\u00a0
\n-> 767.0\u00a0\u00a0\u00a0\u00a0
\nmysql> select GREATEST(“B”,”A”,”C”);\u00a0\u00a0\u00a0\u00a0
\n-> “C”\u00a0\u00a0\u00a0\u00a0\u00a0
\n
\n\u65f6\u671f\u65f6\u95f4\u51fd\u6570\u00a0
\n<\/span>DAYOFWEEK(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u65e5\u671fdate\u662f\u661f\u671f\u51e0(1=\u661f\u671f\u5929,2=\u661f\u671f\u4e00,\u2026\u20267=\u661f\u671f\u516d,ODBC<\/p>\n

\u6807\u51c6)\u00a0\u00a0
\nmysql> select DAYOFWEEK(‘1998-02-03’);\u00a0\u00a0\u00a0\u00a0
\n-> 3\u00a0\u00a0\u00a0\u00a0
\n
\nWEEKDAY(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u65e5\u671fdate\u662f\u661f\u671f\u51e0(0=\u661f\u671f\u4e00,1=\u661f\u671f\u4e8c,\u2026\u20266= \u661f\u671f\u5929)\u3002\u00a0<\/p>\n

\u00a0
\nmysql> select WEEKDAY(‘1997-10-04 22:23:00’);\u00a0\u00a0\u00a0\u00a0
\n-> 5\u00a0\u00a0\u00a0\u00a0
\nmysql> select WEEKDAY(‘1997-11-05’);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\n
\nDAYOFMONTH(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u4e00\u6708\u4e2d\u7684\u7b2c\u51e0\u65e5(\u57281\u523031\u8303\u56f4\u5185)\u00a0\u00a0\u00a0\u00a0
\nmysql> select DAYOFMONTH(‘1998-02-03’);\u00a0\u00a0\u00a0\u00a0
\n-> 3\u00a0\u00a0\u00a0\u00a0
\n
\nDAYOFYEAR(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u4e00\u5e74\u4e2d\u7684\u7b2c\u51e0\u65e5(\u57281\u5230366\u8303\u56f4\u5185)\u00a0\u00a0\u00a0\u00a0
\nmysql> select DAYOFYEAR(‘1998-02-03’);\u00a0\u00a0\u00a0\u00a0
\n-> 34\u00a0\u00a0\u00a0\u00a0
\n
\nMONTH(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u4e2d\u7684\u6708\u4efd\u6570\u503c\u00a0\u00a0\u00a0\u00a0
\nmysql> select MONTH(‘1998-02-03’);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\n
\nDAYNAME(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u661f\u671f\u51e0(\u6309\u82f1\u6587\u540d\u8fd4\u56de)\u00a0\u00a0
\nmysql> select DAYNAME(“1998-02-05”);\u00a0\u00a0\u00a0\u00a0
\n-> ‘Thursday’\u00a0\u00a0\u00a0\u00a0
\n
\nMONTHNAME(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u51e0\u6708(\u6309\u82f1\u6587\u540d\u8fd4\u56de)\u00a0\u00a0
\nmysql> select MONTHNAME(“1998-02-05”);\u00a0\u00a0\u00a0\u00a0
\n-> ‘February’\u00a0\u00a0\u00a0\u00a0
\n
\nQUARTER(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u4e00\u5e74\u7684\u7b2c\u51e0\u4e2a\u5b63\u5ea6\u00a0\u00a0\u00a0\u00a0
\nmysql> select QUARTER(’98-04-01′);\u00a0\u00a0\u00a0\u00a0
\n-> 2\u00a0\u00a0\u00a0\u00a0
\n
\nWEEK(date,first)\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u662f\u4e00\u5e74\u7684\u7b2c\u51e0\u5468(first\u9ed8\u8ba4\u503c0,first\u53d6\u503c1\u8868\u793a\u5468\u4e00\u662f<\/p>\n

\u5468\u7684\u5f00\u59cb,0\u4ece\u5468\u65e5\u5f00\u59cb)\u00a0\u00a0
\nmysql> select WEEK(‘1998-02-20’);\u00a0\u00a0\u00a0\u00a0
\n-> 7\u00a0\u00a0\u00a0\u00a0
\nmysql> select WEEK(‘1998-02-20’,0);\u00a0\u00a0\u00a0\u00a0
\n-> 7\u00a0\u00a0\u00a0\u00a0
\nmysql> select WEEK(‘1998-02-20’,1);\u00a0\u00a0\u00a0\u00a0
\n-> 8\u00a0\u00a0\u00a0\u00a0
\n
\nYEAR(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56dedate\u7684\u5e74\u4efd(\u8303\u56f4\u57281000\u52309999)\u00a0\u00a0\u00a0\u00a0
\nmysql> select YEAR(’98-02-03′);\u00a0\u00a0\u00a0\u00a0
\n-> 1998\u00a0\u00a0\u00a0\u00a0
\n
\nHOUR(time)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56detime\u7684\u5c0f\u65f6\u6570(\u8303\u56f4\u662f0\u523023)\u00a0\u00a0\u00a0
\nmysql> select HOUR(’10:05:03′);\u00a0\u00a0\u00a0\u00a0
\n-> 10\u00a0\u00a0\u00a0\u00a0
\n
\nMINUTE(time)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56detime\u7684\u5206\u949f\u6570(\u8303\u56f4\u662f0\u523059)\u00a0\u00a0\u00a0\u00a0
\nmysql> select MINUTE(’98-02-03 10:05:03′);\u00a0\u00a0\u00a0\u00a0
\n-> 5\u00a0\u00a0\u00a0\u00a0
\n
\nSECOND(time)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56detime\u7684\u79d2\u6570(\u8303\u56f4\u662f0\u523059)\u00a0\u00a0\u00a0
\nmysql> select SECOND(’10:05:03′);\u00a0\u00a0\u00a0\u00a0
\n-> 3\u00a0\u00a0\u00a0\u00a0
\n
\nPERIOD_ADD(P,N)\u00a0\u00a0\u00a0\u00a0
\n\u589e\u52a0N\u4e2a\u6708\u5230\u65f6\u671fP\u5e76\u8fd4\u56de(P\u7684\u683c\u5f0fYYMM\u6216YYYYMM)\u00a0\u00a0\u00a0\u00a0
\nmysql> select PERIOD_ADD(9801,2);\u00a0\u00a0\u00a0\u00a0
\n-> 199803\u00a0\u00a0\u00a0\u00a0
\n
\nPERIOD_DIFF(P1,P2)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u5728\u65f6\u671fP1\u548cP2\u4e4b\u95f4\u6708\u6570(P1\u548cP2\u7684\u683c\u5f0fYYMM\u6216YYYYMM)\u00a0\u00a0
\nmysql> select PERIOD_DIFF(9802,199703);\u00a0\u00a0\u00a0\u00a0
\n-> 11\u00a0\u00a0\u00a0\u00a0
\n
\nDATE_ADD(date,INTERVAL expr type)\u00a0\u00a0
\nDATE_SUB(date,INTERVAL expr type)\u00a0\u00a0\u00a0\u00a0
\nADDDATE(date,INTERVAL expr type)\u00a0\u00a0\u00a0\u00a0
\nSUBDATE(date,INTERVAL expr type)\u00a0\u00a0
\n\u5bf9\u65e5\u671f\u65f6\u95f4\u8fdb\u884c\u52a0\u51cf\u6cd5\u8fd0\u7b97\u00a0\u00a0
\n(ADDDATE()\u548cSUBDATE()\u662fDATE_ADD()\u548cDATE_SUB()\u7684\u540c\u4e49\u8bcd,\u4e5f<\/p>\n

\u53ef\u4ee5\u7528\u8fd0\u7b97\u7b26+\u548c-\u800c\u4e0d\u662f\u51fd\u6570\u00a0\u00a0
\ndate\u662f\u4e00\u4e2aDATETIME\u6216DATE\u503c,expr\u5bf9date\u8fdb\u884c\u52a0\u51cf\u6cd5\u7684\u4e00\u4e2a\u8868<\/p>\n

\u8fbe\u5f0f\u5b57\u7b26\u4e32type\u6307\u660e\u8868\u8fbe\u5f0fexpr\u5e94\u8be5\u5982\u4f55\u88ab\u89e3\u91ca\u00a0\u00a0
\n[type\u503c \u542b\u4e49 \u671f\u671b\u7684expr\u683c\u5f0f]:\u00a0\u00a0
\nSECOND \u79d2 SECONDS\u00a0\u00a0\u00a0\u00a0
\nMINUTE \u5206\u949f MINUTES\u00a0\u00a0\u00a0\u00a0
\nHOUR \u65f6\u95f4 HOURS\u00a0\u00a0\u00a0\u00a0
\nDAY \u5929 DAYS\u00a0\u00a0\u00a0\u00a0
\nMONTH \u6708 MONTHS\u00a0\u00a0\u00a0\u00a0
\nYEAR \u5e74 YEARS\u00a0\u00a0\u00a0\u00a0
\nMINUTE_SECOND \u5206\u949f\u548c\u79d2 “MINUTES:SECONDS”\u00a0\u00a0\u00a0\u00a0
\nHOUR_MINUTE \u5c0f\u65f6\u548c\u5206\u949f “HOURS:MINUTES”\u00a0\u00a0\u00a0\u00a0
\nDAY_HOUR \u5929\u548c\u5c0f\u65f6 “DAYS HOURS”\u00a0\u00a0\u00a0\u00a0
\nYEAR_MONTH \u5e74\u548c\u6708 “YEARS-MONTHS”\u00a0\u00a0\u00a0\u00a0
\nHOUR_SECOND \u5c0f\u65f6, \u5206\u949f\uff0c “HOURS:MINUTES:SECONDS”\u00a0\u00a0\u00a0\u00a0
\nDAY_MINUTE \u5929, \u5c0f\u65f6, \u5206\u949f “DAYS HOURS:MINUTES”\u00a0\u00a0\u00a0\u00a0
\nDAY_SECOND \u5929, \u5c0f\u65f6, \u5206\u949f, \u79d2 “DAYS<\/p>\n

HOURS:MINUTES:SECONDS”\u00a0
\nexpr\u4e2d\u5141\u8bb8\u4efb\u4f55\u6807\u70b9\u505a\u5206\u9694\u7b26,\u5982\u679c\u6240\u6709\u662fDATE\u503c\u65f6\u7ed3\u679c\u662f\u4e00\u4e2a<\/p>\n

DATE\u503c,\u5426\u5219\u7ed3\u679c\u662f\u4e00\u4e2aDATETIME\u503c)\u00a0\u00a0
\n\u5982\u679ctype\u5173\u952e\u8bcd\u4e0d\u5b8c\u6574,\u5219MySQL\u4ece\u53f3\u7aef\u53d6\u503c,DAY_SECOND\u56e0\u4e3a\u7f3a<\/p>\n

\u5c11\u5c0f\u65f6\u5206\u949f\u7b49\u4e8eMINUTE_SECOND)\u00a0\u00a0
\n\u5982\u679c\u589e\u52a0MONTH\u3001YEAR_MONTH\u6216YEAR,\u5929\u6570\u5927\u4e8e\u7ed3\u679c\u6708\u4efd\u7684\u6700\u5927\u5929<\/p>\n

\u6570\u5219\u4f7f\u7528\u6700\u5927\u5929\u6570)\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT “1997-12-31 23:59:59” + INTERVAL 1 SECOND;\u00a0\u00a0<\/p>\n


\n-> 1998-01-01 00:00:00\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT INTERVAL 1 DAY + “1997-12-31”;\u00a0\u00a0\u00a0\u00a0
\n-> 1998-01-01\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT “1998-01-01” – INTERVAL 1 SECOND;\u00a0\u00a0\u00a0\u00a0
\n-> 1997-12-31 23:59:59\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_ADD(“1997-12-31 23:59:59”,INTERVAL 1<\/p>\n

SECOND);\u00a0\u00a0\u00a0\u00a0
\n-> 1998-01-01 00:00:00\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_ADD(“1997-12-31 23:59:59”,INTERVAL 1<\/p>\n

DAY);\u00a0\u00a0\u00a0\u00a0
\n-> 1998-01-01 23:59:59\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_ADD(“1997-12-31 23:59:59”,INTERVAL<\/p>\n

“1:1” MINUTE_SECOND);\u00a0\u00a0\u00a0\u00a0
\n-> 1998-01-01 00:01:00\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_SUB(“1998-01-01 00:00:00”,INTERVAL “1<\/p>\n

1:1:1” DAY_SECOND);\u00a0\u00a0\u00a0\u00a0
\n-> 1997-12-30 22:58:59\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_ADD(“1998-01-01 00:00:00”, INTERVAL “-1<\/p>\n

10” DAY_HOUR);\u00a0\u00a0
\n-> 1997-12-30 14:00:00\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT DATE_SUB(“1998-01-02”, INTERVAL 31 DAY);\u00a0\u00a0\u00a0\u00a0
\n-> 1997-12-02\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT EXTRACT(YEAR FROM “1999-07-02”);\u00a0\u00a0\u00a0\u00a0
\n-> 1999\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT EXTRACT(YEAR_MONTH FROM “1999-07-02<\/p>\n

01:02:03”);\u00a0\u00a0\u00a0\u00a0
\n-> 199907\u00a0\u00a0\u00a0\u00a0
\nmysql> SELECT EXTRACT(DAY_MINUTE FROM “1999-07-02<\/p>\n

01:02:03”);\u00a0\u00a0\u00a0\u00a0
\n-> 20102\u00a0\u00a0\u00a0\u00a0
\n
\nTO_DAYS(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u65e5\u671fdate\u662f\u897f\u51430\u5e74\u81f3\u4eca\u591a\u5c11\u5929(\u4e0d\u8ba1\u7b971582\u5e74\u4ee5\u524d)\u00a0\u00a0
\nmysql> select TO_DAYS(950501);\u00a0\u00a0\u00a0\u00a0
\n-> 728779\u00a0\u00a0\u00a0\u00a0
\nmysql> select TO_DAYS(‘1997-10-07’);\u00a0\u00a0\u00a0\u00a0
\n-> 729669\u00a0\u00a0\u00a0\u00a0
\n
\nFROM_DAYS(N)\u00a0\u00a0\u00a0\u00a0
\n\u7ed9\u51fa\u897f\u51430\u5e74\u81f3\u4eca\u591a\u5c11\u5929\u8fd4\u56deDATE\u503c(\u4e0d\u8ba1\u7b971582\u5e74\u4ee5\u524d)\u00a0\u00a0\u00a0
\nmysql> select FROM_DAYS(729669);\u00a0\u00a0\u00a0\u00a0
\n-> ‘1997-10-07’\u00a0\u00a0\u00a0\u00a0
\n
\nDATE_FORMAT(date,format)\u00a0\u00a0\u00a0\u00a0
\n\u6839\u636eformat\u5b57\u7b26\u4e32\u683c\u5f0f\u5316date\u503c\u00a0\u00a0
\n(\u5728format\u5b57\u7b26\u4e32\u4e2d\u53ef\u7528\u6807\u5fd7\u7b26:\u00a0\u00a0
\n%M \u6708\u540d\u5b57(January\u2026\u2026December)\u00a0\u00a0\u00a0\u00a0
\n%W \u661f\u671f\u540d\u5b57(Sunday\u2026\u2026Saturday)\u00a0\u00a0\u00a0\u00a0
\n%D \u6709\u82f1\u8bed\u524d\u7f00\u7684\u6708\u4efd\u7684\u65e5\u671f(1st, 2nd, 3rd, \u7b49\u7b49\u3002\uff09\u00a0\u00a0\u00a0\u00a0
\n%Y \u5e74, \u6570\u5b57, 4 \u4f4d\u00a0\u00a0\u00a0\u00a0
\n%y \u5e74, \u6570\u5b57, 2 \u4f4d\u00a0\u00a0\u00a0\u00a0
\n%a \u7f29\u5199\u7684\u661f\u671f\u540d\u5b57(Sun\u2026\u2026Sat)\u00a0\u00a0\u00a0\u00a0
\n%d \u6708\u4efd\u4e2d\u7684\u5929\u6570, \u6570\u5b57(00\u2026\u202631)\u00a0\u00a0\u00a0\u00a0
\n%e \u6708\u4efd\u4e2d\u7684\u5929\u6570, \u6570\u5b57(0\u2026\u202631)\u00a0\u00a0\u00a0\u00a0
\n%m \u6708, \u6570\u5b57(01\u2026\u202612)\u00a0\u00a0\u00a0\u00a0
\n%c \u6708, \u6570\u5b57(1\u2026\u202612)\u00a0\u00a0\u00a0\u00a0
\n%b \u7f29\u5199\u7684\u6708\u4efd\u540d\u5b57(Jan\u2026\u2026Dec)\u00a0\u00a0\u00a0\u00a0
\n%j \u4e00\u5e74\u4e2d\u7684\u5929\u6570(001\u2026\u2026366)\u00a0\u00a0\u00a0\u00a0
\n%H \u5c0f\u65f6(00\u2026\u202623)\u00a0\u00a0\u00a0\u00a0
\n%k \u5c0f\u65f6(0\u2026\u202623)\u00a0\u00a0\u00a0\u00a0
\n%h \u5c0f\u65f6(01\u2026\u202612)\u00a0\u00a0\u00a0\u00a0
\n%I \u5c0f\u65f6(01\u2026\u202612)\u00a0\u00a0\u00a0\u00a0
\n%l \u5c0f\u65f6(1\u2026\u202612)\u00a0\u00a0\u00a0\u00a0
\n%i \u5206\u949f, \u6570\u5b57(00\u2026\u202659)\u00a0\u00a0\u00a0\u00a0
\n%r \u65f6\u95f4,12 \u5c0f\u65f6(hh:mm:ss [AP]M)\u00a0\u00a0\u00a0\u00a0
\n%T \u65f6\u95f4,24 \u5c0f\u65f6(hh:mm:ss)\u00a0\u00a0\u00a0\u00a0
\n%S \u79d2(00\u2026\u202659)\u00a0\u00a0\u00a0\u00a0
\n%s \u79d2(00\u2026\u202659)\u00a0\u00a0\u00a0\u00a0
\n%p AM\u6216PM\u00a0\u00a0\u00a0\u00a0
\n%w \u4e00\u4e2a\u661f\u671f\u4e2d\u7684\u5929\u6570(0=Sunday \u2026\u20266=Saturday \uff09\u00a0\u00a0\u00a0\u00a0
\n%U \u661f\u671f(0\u2026\u202652), \u8fd9\u91cc\u661f\u671f\u5929\u662f\u661f\u671f\u7684\u7b2c\u4e00\u5929\u00a0\u00a0\u00a0\u00a0
\n%u \u661f\u671f(0\u2026\u202652), \u8fd9\u91cc\u661f\u671f\u4e00\u662f\u661f\u671f\u7684\u7b2c\u4e00\u5929\u00a0\u00a0\u00a0\u00a0
\n%% \u5b57\u7b26% )\u00a0\u00a0
\nmysql> select DATE_FORMAT(‘1997-10-04 22:23:00′,’%W %M %<\/p>\n

Y’);\u00a0\u00a0\u00a0\u00a0
\n-> ‘Saturday October 1997’\u00a0\u00a0\u00a0\u00a0
\nmysql> select DATE_FORMAT(‘1997-10-04 22:23:00′,’%H:%i:%<\/p>\n

s’);\u00a0\u00a0\u00a0\u00a0
\n-> ’22:23:00′\u00a0\u00a0\u00a0\u00a0
\nmysql> select DATE_FORMAT(‘1997-10-04 22:23:00′,’%D %y %a<\/p>\n

%d %m %b %j’);\u00a0\u00a0\u00a0\u00a0
\n-> ‘4th 97 Sat 04 10 Oct 277’\u00a0\u00a0\u00a0\u00a0
\nmysql> select DATE_FORMAT(‘1997-10-04 22:23:00′,’%H %k %I<\/p>\n

%r %T %S %w’);\u00a0\u00a0\u00a0\u00a0
\n-> ’22 22 10 10:23:00 PM 22:23:00 00 6′\u00a0\u00a0\u00a0\u00a0
\n
\nTIME_FORMAT(time,format)\u00a0\u00a0
\n\u548cDATE_FORMAT()\u7c7b\u4f3c,\u4f46TIME_FORMAT\u53ea\u5904\u7406\u5c0f\u65f6\u3001\u5206\u949f\u548c\u79d2(\u5176<\/p>\n

\u4f59\u7b26\u53f7\u4ea7\u751f\u4e00\u4e2aNULL\u503c\u62160)\u00a0\u00a0
\n
\nCURDATE()\u00a0\u00a0\u00a0\u00a0\u00a0
\nCURRENT_DATE()\u00a0\u00a0
\n\u4ee5’YYYY-MM-DD’\u6216YYYYMMDD\u683c\u5f0f\u8fd4\u56de\u5f53\u524d\u65e5\u671f\u503c(\u6839\u636e\u8fd4\u56de\u503c\u6240<\/p>\n

\u5904\u4e0a\u4e0b\u6587\u662f\u5b57\u7b26\u4e32\u6216\u6570\u5b57)\u00a0\u00a0\u00a0\u00a0
\nmysql> select CURDATE();\u00a0\u00a0\u00a0\u00a0
\n-> ‘1997-12-15’\u00a0\u00a0\u00a0\u00a0
\nmysql> select CURDATE() + 0;\u00a0\u00a0\u00a0\u00a0
\n-> 19971215\u00a0\u00a0\u00a0\u00a0
\n
\nCURTIME()\u00a0\u00a0\u00a0\u00a0
\nCURRENT_TIME()\u00a0\u00a0
\n\u4ee5’HH:MM:SS’\u6216HHMMSS\u683c\u5f0f\u8fd4\u56de\u5f53\u524d\u65f6\u95f4\u503c(\u6839\u636e\u8fd4\u56de\u503c\u6240\u5904\u4e0a<\/p>\n

\u4e0b\u6587\u662f\u5b57\u7b26\u4e32\u6216\u6570\u5b57)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0
\nmysql> select CURTIME();\u00a0\u00a0\u00a0\u00a0
\n-> ’23:50:26′\u00a0\u00a0\u00a0\u00a0
\nmysql> select CURTIME() + 0;\u00a0\u00a0\u00a0\u00a0
\n-> 235026\u00a0\u00a0\u00a0\u00a0
\n
\nNOW()\u00a0\u00a0\u00a0\u00a0
\nSYSDATE()\u00a0\u00a0\u00a0\u00a0
\nCURRENT_TIMESTAMP()\u00a0\u00a0
\n\u4ee5’YYYY-MM-DD HH:MM:SS’\u6216YYYYMMDDHHMMSS\u683c\u5f0f\u8fd4\u56de\u5f53\u524d\u65e5\u671f<\/p>\n

\u65f6\u95f4(\u6839\u636e\u8fd4\u56de\u503c\u6240\u5904\u4e0a\u4e0b\u6587\u662f\u5b57\u7b26\u4e32\u6216\u6570\u5b57)\u00a0\u00a0\u00a0\u00a0\u00a0
\nmysql> select NOW();\u00a0\u00a0\u00a0\u00a0
\n-> ‘1997-12-15 23:50:26’\u00a0\u00a0\u00a0\u00a0
\nmysql> select NOW() + 0;\u00a0\u00a0\u00a0\u00a0
\n-> 19971215235026\u00a0\u00a0\u00a0\u00a0
\n
\nUNIX_TIMESTAMP()\u00a0\u00a0\u00a0\u00a0
\nUNIX_TIMESTAMP(date)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56de\u4e00\u4e2aUnix\u65f6\u95f4\u6233(\u4ece’1970-01-01 00:00:00’GMT\u5f00\u59cb\u7684\u79d2<\/p>\n

\u6570,date\u9ed8\u8ba4\u503c\u4e3a\u5f53\u524d\u65f6\u95f4)\u00a0\u00a0
\nmysql> select UNIX_TIMESTAMP();\u00a0\u00a0\u00a0\u00a0
\n-> 882226357\u00a0\u00a0\u00a0\u00a0
\nmysql> select UNIX_TIMESTAMP(‘1997-10-04 22:23:00’);\u00a0\u00a0\u00a0\u00a0
\n-> 875996580\u00a0\u00a0\u00a0\u00a0
\n
\nFROM_UNIXTIME(unix_timestamp)\u00a0\u00a0\u00a0\u00a0
\n\u4ee5’YYYY-MM-DD HH:MM:SS’\u6216YYYYMMDDHHMMSS\u683c\u5f0f\u8fd4\u56de\u65f6\u95f4\u6233\u7684<\/p>\n

\u503c(\u6839\u636e\u8fd4\u56de\u503c\u6240\u5904\u4e0a\u4e0b\u6587\u662f\u5b57\u7b26\u4e32\u6216\u6570\u5b57)\u00a0\u00a0\u00a0\u00a0\u00a0
\nmysql> select FROM_UNIXTIME(875996580);\u00a0\u00a0\u00a0\u00a0
\n-> ‘1997-10-04 22:23:00’\u00a0\u00a0\u00a0\u00a0
\nmysql> select FROM_UNIXTIME(875996580) + 0;\u00a0\u00a0\u00a0\u00a0
\n-> 19971004222300\u00a0\u00a0\u00a0\u00a0
\n
\nFROM_UNIXTIME(unix_timestamp,format)\u00a0\u00a0\u00a0\u00a0
\n\u4ee5format\u5b57\u7b26\u4e32\u683c\u5f0f\u8fd4\u56de\u65f6\u95f4\u6233\u7684\u503c\u00a0\u00a0
\nmysql> select FROM_UNIXTIME(UNIX_TIMESTAMP(),’%Y %D %M %<\/p>\n

h:%i:%s %x’);\u00a0\u00a0\u00a0\u00a0
\n-> ‘1997 23rd December 03:43:30 x’\u00a0\u00a0\u00a0\u00a0
\n
\nSEC_TO_TIME(seconds)\u00a0\u00a0\u00a0\u00a0
\n\u4ee5’HH:MM:SS’\u6216HHMMSS\u683c\u5f0f\u8fd4\u56de\u79d2\u6570\u8f6c\u6210\u7684TIME\u503c(\u6839\u636e\u8fd4\u56de\u503c<\/p>\n

\u6240\u5904\u4e0a\u4e0b\u6587\u662f\u5b57\u7b26\u4e32\u6216\u6570\u5b57)\u00a0\u00a0\u00a0\u00a0\u00a0
\nmysql> select SEC_TO_TIME(2378);\u00a0\u00a0\u00a0\u00a0
\n-> ’00:39:38′\u00a0\u00a0\u00a0\u00a0
\nmysql> select SEC_TO_TIME(2378) + 0;\u00a0\u00a0\u00a0\u00a0
\n-> 3938\u00a0\u00a0\u00a0\u00a0
\n
\nTIME_TO_SEC(time)\u00a0\u00a0\u00a0\u00a0
\n\u8fd4\u56detime\u503c\u6709\u591a\u5c11\u79d2\u00a0\u00a0\u00a0\u00a0
\nmysql> select TIME_TO_SEC(’22:23:00′);\u00a0\u00a0\u00a0\u00a0
\n-> 80580\u00a0\u00a0\u00a0\u00a0
\nmysql> select TIME_TO_SEC(’00:39:38′);\u00a0\u00a0\u00a0\u00a0
\n-> 2378\u00a0<\/p>\n

<\/p>\n

\u8f6c\u6362\u51fd\u6570<\/span><\/p>\n

cast
\n\u7528\u6cd5\uff1acast(\u5b57\u6bb5 as \u6570\u636e\u7c7b\u578b) [\u5f53\u7136\u662f\u5426\u53ef\u4ee5\u6210\u529f\u8f6c\u6362\uff0c\u8fd8\u8981\u770b\u6570\u636e\u7c7b\u578b\u5f3a\u5236\u8f6c\u5316\u65f6\u6ce8\u610f\u7684\u95ee\u9898]
\n\u5b9e\u4f8b\uff1aselect cast(a as unsigned) as b from cardserver where order by b desc;<\/span><\/p>\n

convert\uff1a<\/p>\n

\u7528\u6cd5\uff1aconvert(\u5b57\u6bb5,\u6570\u636e\u7c7b\u578b)
\n\u5b9e\u4f8b\uff1aselect convert(a ,unsigned) as b from cardserver where order by b desc;<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

\u5b57\u7b26\u4e32\u51fd\u6570 ASCII(str)\u00a0\u00a0\u00a0 \u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u7b2c\u4e00\u4e2a\u5b57\u7b26\u7684ASCII\u503c(str\u662f\u7a7a\u4e32\u65f6\u8fd4\u56de0)\u00a0\u00a0 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-171","post","type-post","status-publish","format-standard","hentry","category-php"],"_links":{"self":[{"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/posts\/171","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=171"}],"version-history":[{"count":1,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/posts\/171\/revisions"}],"predecessor-version":[{"id":441,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=\/wp\/v2\/posts\/171\/revisions\/441"}],"wp:attachment":[{"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=171"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=171"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.siediyer.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=171"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}