{"id":288,"date":"2009-12-12T09:39:46","date_gmt":"2009-12-12T01:39:46","guid":{"rendered":"http:\/\/elon.852128.com\/blog\/?p=288"},"modified":"2010-06-27T12:45:02","modified_gmt":"2010-06-27T04:45:02","slug":"mysql%e7%9a%84%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"https:\/\/elon.852128.com\/blog\/2009\/12\/12\/mysql%e7%9a%84%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%87%bd%e6%95%b0\/","title":{"rendered":"mysql\u7684\u5b57\u7b26\u4e32\u51fd\u6570"},"content":{"rendered":"

\u5bf9\u4e8e\u9488\u5bf9\u5b57\u7b26\u4e32\u4f4d\u7f6e\u7684\u64cd\u4f5c\uff0c\u7b2c\u4e00\u4e2a\u4f4d\u7f6e\u88ab\u6807\u8bb0\u4e3a1\u3002<\/p>\n

ASCII(str)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u6700\u5de6\u9762\u5b57\u7b26\u7684ASCII\u4ee3\u7801\u503c\u3002\u5982\u679cstr\u662f\u7a7a\u5b57\u7b26\u4e32\uff0c\u8fd4\u56de0\u3002\u5982\u679cstr\u662fNULL\uff0c\u8fd4\u56deNULL\u3002
\nmysql> select ASCII(‘2’);
\n\u00a0 -> 50
\nmysql> select ASCII(2);
\n\u00a0 -> 50
\nmysql> select ASCII(‘dx’);
\n\u00a0 -> 100\u4e5f\u53ef\u53c2\u89c1ORD()\u51fd\u6570\u3002
\nORD(str)<\/strong>
\n\u5982\u679c\u5b57\u7b26\u4e32str\u6700\u5de6\u9762\u5b57\u7b26\u662f\u4e00\u4e2a\u591a\u5b57\u8282\u5b57\u7b26\uff0c\u901a\u8fc7\u4ee5\u683c\u5f0f((first byte ASCII code)*256+(second byte ASCII code))[*256+third byte ASCII code…]\u8fd4\u56de\u5b57\u7b26\u7684ASCII\u4ee3\u7801\u503c\u6765\u8fd4\u56de\u591a\u5b57\u8282\u5b57\u7b26\u4ee3\u7801\u3002\u5982\u679c\u6700\u5de6\u9762\u7684\u5b57\u7b26\u4e0d\u662f\u4e00\u4e2a\u591a\u5b57\u8282\u5b57\u7b26\u3002\u8fd4\u56de\u4e0eASCII()\u51fd\u6570\u8fd4\u56de\u7684\u76f8\u540c\u503c\u3002
\nmysql> select ORD(‘2’);
\n\u00a0 -> 50
\n\u00a0CONV(N,from_base,to_base)<\/strong>
\n\u5728\u4e0d\u540c\u7684\u6570\u5b57\u57fa\u4e4b\u95f4\u53d8\u6362\u6570\u5b57\u3002\u8fd4\u56de\u6570\u5b57N\u7684\u5b57\u7b26\u4e32\u6570\u5b57\uff0c\u4ecefrom_base\u57fa\u53d8\u6362\u4e3ato_base\u57fa\uff0c\u5982\u679c\u4efb\u4f55\u53c2\u6570\u662fNULL\uff0c\u8fd4\u56deNULL\u3002\u53c2\u6570N\u89e3\u91ca\u4e3a\u4e00\u4e2a\u6574\u6570\uff0c\u4f46\u662f\u53ef\u4ee5\u6307\u5b9a\u4e3a\u4e00\u4e2a\u6574\u6570\u6216\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002\u6700\u5c0f\u57fa\u662f2\u4e14\u6700\u5927\u7684\u57fa\u662f36\u3002\u5982\u679cto_base\u662f\u4e00\u4e2a\u8d1f\u6570\uff0cN\u88ab\u8ba4\u4e3a\u662f\u4e00\u4e2a\u6709\u7b26\u53f7\u6570\uff0c\u5426\u5219\uff0cN\u88ab\u5f53\u4f5c\u65e0\u7b26\u53f7\u6570\u3002 CONV\u4ee564\u4f4d\u70b9\u7cbe\u5ea6\u5de5\u4f5c\u3002
\nmysql> select CONV(“a”,16,2);
\n\u00a0 -> ‘1010’
\nmysql> select CONV(“6E”,18,8);
\n\u00a0 -> ‘172’
\nmysql> select CONV(-17,10,-18);
\n\u00a0 -> ‘-H’
\nmysql> select CONV(10+”10″+’10’+0xa,10,10);
\n\u00a0 -> ’40’
\n\u00a0BIN(N)<\/strong>
\n\u8fd4\u56de\u4e8c\u8fdb\u5236\u503cN\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u8868\u793a\uff0c\u5728\u6b64N\u662f\u4e00\u4e2a\u957f\u6574\u6570(BIGINT)\u6570\u5b57\uff0c\u8fd9\u7b49\u4ef7\u4e8eCONV(N,10,2)\u3002\u5982\u679cN\u662fNULL\uff0c\u8fd4\u56deNULL\u3002
\nmysql> select BIN(12);
\n\u00a0 -> ‘1100’
\nOCT(N)<\/strong>
\n\u8fd4\u56de\u516b\u8fdb\u5236\u503cN\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u8868\u793a\uff0c\u5728\u6b64N\u662f\u4e00\u4e2a\u957f\u6574\u578b\u6570\u5b57\uff0c\u8fd9\u7b49\u4ef7\u4e8eCONV(N,10,8)\u3002\u5982\u679cN\u662fNULL\uff0c\u8fd4\u56deNULL\u3002
\nmysql> select OCT(12);
\n\u00a0 -> ’14’
\n\u00a0HEX(N)<\/strong>
\n\u8fd4\u56de\u5341\u516d\u8fdb\u5236\u503cN\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u8868\u793a\uff0c\u5728\u6b64N\u662f\u4e00\u4e2a\u957f\u6574\u578b(BIGINT)\u6570\u5b57\uff0c\u8fd9\u7b49\u4ef7\u4e8eCONV(N,10,16)\u3002\u5982\u679cN\u662fNULL\uff0c\u8fd4\u56deNULL\u3002
\nmysql> select HEX(255);
\n\u00a0 -> ‘FF’
\n\u00a0CHAR(N,…)<\/strong>
\nCHAR()\u5c06\u53c2\u6570\u89e3\u91ca\u4e3a\u6574\u6570\u5e76\u4e14\u8fd4\u56de\u7531\u8fd9\u4e9b\u6574\u6570\u7684ASCII\u4ee3\u7801\u5b57\u7b26\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002NULL\u503c\u88ab\u8df3\u8fc7\u3002
\nmysql> select CHAR(77,121,83,81,’76’);
\n\u00a0 -> ‘MySQL’
\nmysql> select CHAR(77,77.3,’77.3′);
\n\u00a0 -> ‘MMM’
\n\u00a0CONCAT(str1,str2,…)<\/strong>
\n\u8fd4\u56de\u6765\u81ea\u4e8e\u53c2\u6570\u8fde\u7ed3\u7684\u5b57\u7b26\u4e32\u3002\u5982\u679c\u4efb\u4f55\u53c2\u6570\u662fNULL\uff0c\u8fd4\u56deNULL\u3002\u53ef\u4ee5\u6709\u8d85\u8fc72\u4e2a\u7684\u53c2\u6570\u3002\u4e00\u4e2a\u6570\u5b57\u53c2\u6570\u88ab\u53d8\u6362\u4e3a\u7b49\u4ef7\u7684\u5b57\u7b26\u4e32\u5f62\u5f0f\u3002
\nmysql> select CONCAT(‘My’, ‘S’, ‘QL’);
\n\u00a0 -> ‘MySQL’
\nmysql> select CONCAT(‘My’, NULL, ‘QL’);
\n\u00a0 -> NULL
\nmysql> select CONCAT(14.3);
\n\u00a0 -> ‘14.3’
\nLENGTH(str)
\n\u3000
\nOCTET_LENGTH(str)<\/strong>
\n\u3000
\nCHAR_LENGTH(str)<\/strong>
\n\u3000
\nCHARACTER_LENGTH(str)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u957f\u5ea6\u3002
\nmysql> select LENGTH(‘text’);
\n\u00a0 -> 4
\nmysql> select OCTET_LENGTH(‘text’);
\n\u00a0 -> 4
\n\u6ce8\u610f\uff0c\u5bf9\u4e8e\u591a\u5b57\u8282\u5b57\u7b26\uff0c\u5176CHAR_LENGTH()\u4ec5\u8ba1\u7b97\u4e00\u6b21\u3002
\nLOCATE(substr,str)<\/strong>
\n\u3000
\nPOSITION(substr IN str)<\/strong>
\n\u8fd4\u56de\u5b50\u4e32substr\u5728\u5b57\u7b26\u4e32str\u7b2c\u4e00\u4e2a\u51fa\u73b0\u7684\u4f4d\u7f6e\uff0c\u5982\u679csubstr\u4e0d\u662f\u5728str\u91cc\u9762\uff0c\u8fd4\u56de0.
\nmysql> select LOCATE(‘bar’, ‘foobarbar’);
\n\u00a0 -> 4
\nmysql> select LOCATE(‘xbar’, ‘foobar’);
\n\u00a0 -> 0
\n\u8be5\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002<\/p>\n

LOCATE(substr,str,pos)<\/strong>
\n\u8fd4\u56de\u5b50\u4e32substr\u5728\u5b57\u7b26\u4e32str\u7b2c\u4e00\u4e2a\u51fa\u73b0\u7684\u4f4d\u7f6e\uff0c\u4ece\u4f4d\u7f6epos\u5f00\u59cb\u3002\u5982\u679csubstr\u4e0d\u662f\u5728str\u91cc\u9762\uff0c\u8fd4\u56de0\u3002
\nmysql> select LOCATE(‘bar’, ‘foobarbar’,5);
\n\u00a0 -> 7
\n\u8fd9\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nINSTR(str,substr)<\/strong>
\n\u8fd4\u56de\u5b50\u4e32substr\u5728\u5b57\u7b26\u4e32str\u4e2d\u7684\u7b2c\u4e00\u4e2a\u51fa\u73b0\u7684\u4f4d\u7f6e\u3002\u8fd9\u4e0e\u67092\u4e2a\u53c2\u6570\u5f62\u5f0f\u7684LOCATE()\u76f8\u540c\uff0c\u9664\u4e86\u53c2\u6570\u88ab\u98a0\u5012\u3002
\nmysql> select INSTR(‘foobarbar’, ‘bar’);
\n\u00a0 -> 4
\nmysql> select INSTR(‘xbar’, ‘foobar’);
\n\u00a0 -> 0
\n\u8fd9\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nLPAD(str,len,padstr)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u5de6\u9762\u7528\u5b57\u7b26\u4e32padstr\u586b\u8865\u76f4\u5230str\u662flen\u4e2a\u5b57\u7b26\u957f\u3002
\nmysql> select LPAD(‘hi’,4,’??’);
\n\u00a0 -> ‘??hi’
\n\u00a0RPAD(str,len,padstr)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u53f3\u9762\u7528\u5b57\u7b26\u4e32padstr\u586b\u8865\u76f4\u5230str\u662flen\u4e2a\u5b57\u7b26\u957f\u3002
\nmysql> select RPAD(‘hi’,5,’?’);
\n\u00a0 -> ‘hi???’
\nLEFT(str,len)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u6700\u5de6\u9762len\u4e2a\u5b57\u7b26\u3002
\nmysql> select LEFT(‘foobarbar’, 5);
\n\u00a0 -> ‘fooba’
\n\u8be5\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nRIGHT(str,len)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\u7684\u6700\u53f3\u9762len\u4e2a\u5b57\u7b26\u3002
\nmysql> select RIGHT(‘foobarbar’, 4);
\n\u00a0 -> ‘rbar’
\n\u8be5\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nSUBSTRING(str,pos,len)
\n\u3000
\nSUBSTRING(str FROM pos FOR len)
\n\u3000
\nMID(str,pos,len)<\/strong>
\n\u4ece\u5b57\u7b26\u4e32str\u8fd4\u56de\u4e00\u4e2alen\u4e2a\u5b57\u7b26\u7684\u5b50\u4e32\uff0c\u4ece\u4f4d\u7f6epos\u5f00\u59cb\u3002\u4f7f\u7528FROM\u7684\u53d8\u79cd\u5f62\u5f0f\u662fANSI SQL92\u8bed\u6cd5\u3002
\nmysql> select SUBSTRING(‘Quadratically’,5,6);
\n\u00a0 -> ‘ratica’
\n\u8be5\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nSUBSTRING(str,pos)
\n\u3000
\nSUBSTRING(str FROM pos)<\/strong>
\n\u4ece\u5b57\u7b26\u4e32str\u7684\u8d77\u59cb\u4f4d\u7f6epos\u8fd4\u56de\u4e00\u4e2a\u5b50\u4e32\u3002
\nmysql> select SUBSTRING(‘Quadratically’,5);
\n\u00a0 -> ‘ratically’
\nmysql> select SUBSTRING(‘foobarbar’ FROM 4);
\n\u00a0 -> ‘barbar’
\n\u8be5\u51fd\u6570\u662f\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nSUBSTRING_INDEX(str,delim,count)<\/strong>
\n\u8fd4\u56de\u4ece\u5b57\u7b26\u4e32str\u7684\u7b2ccount\u4e2a\u51fa\u73b0\u7684\u5206\u9694\u7b26delim\u4e4b\u540e\u7684\u5b50\u4e32\u3002\u5982\u679ccount\u662f\u6b63\u6570\uff0c\u8fd4\u56de\u6700\u540e\u7684\u5206\u9694\u7b26\u5230\u5de6\u8fb9(\u4ece\u5de6\u8fb9\u6570) \u7684\u6240\u6709\u5b57\u7b26\u3002\u5982\u679ccount\u662f\u8d1f\u6570\uff0c\u8fd4\u56de\u6700\u540e\u7684\u5206\u9694\u7b26\u5230\u53f3\u8fb9\u7684\u6240\u6709\u5b57\u7b26(\u4ece\u53f3\u8fb9\u6570)\u3002
\nmysql> select SUBSTRING_INDEX(‘www.mysql.com’, ‘.’, 2);
\n\u00a0 -> ‘www.mysql’
\nmysql> select SUBSTRING_INDEX(‘www.mysql.com’, ‘.’, -2);
\n\u00a0 -> ‘mysql.com’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nLTRIM(str)<\/strong>
\n\u8fd4\u56de\u5220\u9664\u4e86\u5176\u524d\u7f6e\u7a7a\u683c\u5b57\u7b26\u7684\u5b57\u7b26\u4e32str\u3002
\nmysql> select LTRIM(‘ barbar’);
\n\u00a0 -> ‘barbar’
\nRTRIM(str)<\/strong>
\n\u8fd4\u56de\u5220\u9664\u4e86\u5176\u62d6\u540e\u7a7a\u683c\u5b57\u7b26\u7684\u5b57\u7b26\u4e32str\u3002
\nmysql> select RTRIM(‘barbar ‘);
\n\u00a0 -> ‘barbar’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002 TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u5176\u6240\u6709remstr\u524d\u7f00\u6216\u540e\u7f00\u88ab\u5220\u9664\u4e86\u3002\u5982\u679c\u6ca1\u6709\u4fee\u9970\u7b26BOTH\u3001LEADING\u6216TRAILING\u7ed9\u51fa\uff0cBOTH\u88ab\u5047\u5b9a\u3002\u5982\u679cremstr\u6ca1\u88ab\u6307\u5b9a\uff0c\u7a7a\u683c\u88ab\u5220\u9664\u3002
\nmysql> select TRIM(‘ bar ‘);
\n\u00a0 -> ‘bar’
\nmysql> select TRIM(LEADING ‘x’ FROM ‘xxxbarxxx’);
\n\u00a0 -> ‘barxxx’
\nmysql> select TRIM(BOTH ‘x’ FROM ‘xxxbarxxx’);
\n\u00a0 -> ‘bar’
\nmysql> select TRIM(TRAILING ‘xyz’ FROM ‘barxxyz’);
\n\u00a0 -> ‘barx’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nSOUNDEX(str)<\/strong>
\n\u8fd4\u56destr\u7684\u4e00\u4e2a\u540c\u97f3\u5b57\u7b26\u4e32\u3002\u542c\u8d77\u6765\u201c\u5927\u81f4\u76f8\u540c\u201d\u76842\u4e2a\u5b57\u7b26\u4e32\u5e94\u8be5\u6709\u76f8\u540c\u7684\u540c\u97f3\u5b57\u7b26\u4e32\u3002\u4e00\u4e2a\u201c\u6807\u51c6\u201d\u7684\u540c\u97f3\u5b57\u7b26\u4e32\u957f\u662f4\u4e2a\u5b57\u7b26\uff0c\u4f46\u662fSOUNDEX()\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a\u4efb\u610f\u957f\u7684\u5b57\u7b26\u4e32\u3002\u4f60\u53ef\u4ee5\u5728\u7ed3\u679c\u4e0a\u4f7f\u7528SUBSTRING()\u5f97\u5230\u4e00\u4e2a\u201c\u6807\u51c6\u201d\u7684 \u540c\u97f3\u4e32\u3002\u6240\u6709\u975e\u6570\u5b57\u5b57\u6bcd\u5b57\u7b26\u5728\u7ed9\u5b9a\u7684\u5b57\u7b26\u4e32\u4e2d\u88ab\u5ffd\u7565\u3002\u6240\u6709\u5728A-Z\u4e4b\u5916\u7684\u5b57\u7b26\u56fd\u9645\u5b57\u6bcd\u88ab\u5f53\u4f5c\u5143\u97f3\u3002
\nmysql> select SOUNDEX(‘Hello’);
\n\u00a0 -> ‘H400’
\nmysql> select SOUNDEX(‘Quadratically’);
\n\u00a0 -> ‘Q36324’
\n\u00a0SPACE(N)<\/strong>
\n\u8fd4\u56de\u7531N\u4e2a\u7a7a\u683c\u5b57\u7b26\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002
\nmysql> select SPACE(6);
\n\u00a0 -> ‘ ‘
\n\u00a0REPLACE(str,from_str,to_str)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u5176\u5b57\u7b26\u4e32from_str\u7684\u6240\u6709\u51fa\u73b0\u7531\u5b57\u7b26\u4e32to_str\u4ee3\u66ff\u3002
\nmysql> select REPLACE(‘www.mysql.com’, ‘w’, ‘Ww’);
\n\u00a0 -> ‘WwWwWw.mysql.com’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nREPEAT(str,count)<\/strong>
\n\u8fd4\u56de\u7531\u91cd\u590dcountTimes\u6b21\u7684\u5b57\u7b26\u4e32str\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002\u5982\u679ccount <= 0\uff0c\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5b57\u7b26\u4e32\u3002\u5982\u679cstr\u6216count\u662fNULL\uff0c\u8fd4\u56deNULL\u3002
\nmysql> select REPEAT(‘MySQL’, 3);
\n\u00a0 -> ‘MySQLMySQLMySQL’
\n\u00a0REVERSE(str)<\/strong>
\n\u8fd4\u56de\u98a0\u5012\u5b57\u7b26\u987a\u5e8f\u7684\u5b57\u7b26\u4e32str\u3002
\nmysql> select REVERSE(‘abc’);
\n\u00a0 -> ‘cba’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u53ef\u9760\u7684\u3002
\nINSERT(str,pos,len,newstr)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u5728\u4f4d\u7f6epos\u8d77\u59cb\u7684\u5b50\u4e32\u4e14len\u4e2a\u5b57\u7b26\u957f\u5f97\u5b50\u4e32\u7531\u5b57\u7b26\u4e32newstr\u4ee3\u66ff\u3002
\nmysql> select INSERT(‘Quadratic’, 3, 4, ‘What’);
\n\u00a0 -> ‘QuWhattic’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nELT(N,str1,str2,str3,…)<\/strong>
\n\u5982\u679cN= 1\uff0c\u8fd4\u56destr1\uff0c\u5982\u679cN= 2\uff0c\u8fd4\u56destr2\uff0c\u7b49\u7b49\u3002\u5982\u679cN\u5c0f\u4e8e1\u6216\u5927\u4e8e\u53c2\u6570\u4e2a\u6570\uff0c\u8fd4\u56deNULL\u3002ELT()\u662fFIELD()\u53cd\u8fd0\u7b97\u3002
\nmysql> select ELT(1, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);
\n\u00a0 -> ‘ej’
\nmysql> select ELT(4, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);
\n\u00a0 -> ‘foo’
\nFIELD(str,str1,str2,str3,…)<\/strong>
\n\u8fd4\u56destr\u5728str1, str2, str3, …\u6e05\u5355\u7684\u7d22\u5f15\u3002\u5982\u679cstr\u6ca1\u627e\u5230\uff0c\u8fd4\u56de0\u3002FIELD()\u662fELT()\u53cd\u8fd0\u7b97\u3002
\nmysql> select FIELD(‘ej’, ‘Hej’, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);
\n\u00a0 -> 2
\nmysql> select FIELD(‘fo’, ‘Hej’, ‘ej’, ‘Heja’, ‘hej’, ‘foo’);
\n\u00a0 -> 0
\nFIND_IN_SET(str,strlist)<\/strong>
\n\u5982\u679c\u5b57\u7b26\u4e32str\u5728\u7531N\u5b50\u4e32\u7ec4\u6210\u7684\u8868strlist\u4e4b\u4e2d\uff0c\u8fd4\u56de\u4e00\u4e2a1\u5230N\u7684\u503c\u3002\u4e00\u4e2a\u5b57\u7b26\u4e32\u8868\u662f\u88ab\u201c,\u201d\u5206\u9694\u7684\u5b50\u4e32\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002\u5982\u679c\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u4e00\u4e2a\u5e38\u6570\u5b57\u7b26\u4e32\u5e76\u4e14\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u4e00\u79cd\u7c7b\u578b\u4e3aSET\u7684\u5217\uff0cFIND_IN_SET()\u51fd\u6570\u88ab\u4f18\u5316\u800c\u4f7f\u7528\u4f4d\u8fd0\u7b97\uff01\u5982\u679cstr\u4e0d\u662f\u5728strlist\u91cc\u9762\u6216\u5982\u679cstrlist\u662f\u7a7a\u5b57\u7b26\u4e32\uff0c\u8fd4\u56de0\u3002\u5982\u679c\u4efb\u4f55\u4e00\u4e2a\u53c2\u6570\u662fNULL\uff0c\u8fd4\u56deNULL\u3002\u5982\u679c\u7b2c\u4e00\u4e2a\u53c2\u6570\u5305\u542b\u4e00\u4e2a\u201c,\u201d\uff0c\u8be5\u51fd\u6570\u5c06\u5de5\u4f5c\u4e0d\u6b63\u5e38\u3002
\nmysql> SELECT FIND_IN_SET(‘b’,’a,b,c,d’);
\n\u00a0 -> 2
\n\u00a0MAKE_SET(bits,str1,str2,…)<\/strong>
\n\u8fd4\u56de\u4e00\u4e2a\u96c6\u5408 (\u5305\u542b\u7531\u201c,\u201d\u5b57\u7b26\u5206\u9694\u7684\u5b50\u4e32\u7ec4\u6210\u7684\u4e00\u4e2a\u5b57\u7b26\u4e32)\uff0c\u7531\u76f8\u5e94\u7684\u4f4d\u5728bits\u96c6\u5408\u4e2d\u7684\u7684\u5b57\u7b26\u4e32\u7ec4\u6210\u3002str1\u5bf9\u5e94\u4e8e\u4f4d0\uff0cstr2\u5bf9\u5e94\u4f4d1\uff0c\u7b49\u7b49\u3002\u5728str1, str2, …\u4e2d\u7684NULL\u4e32\u4e0d\u6dfb\u52a0\u5230\u7ed3\u679c\u4e2d\u3002
\nmysql> SELECT MAKE_SET(1,’a’,’b’,’c’);
\n\u00a0 -> ‘a’
\nmysql> SELECT MAKE_SET(1 | 4,’hello’,’nice’,’world’);
\n\u00a0 -> ‘hello,world’
\nmysql> SELECT MAKE_SET(0,’a’,’b’,’c’);
\n\u00a0 -> ”
\nEXPORT_SET(bits,on,off,[separator,[number_of_bits]])<\/strong>
\n\u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u5728\u8fd9\u91cc\u5bf9\u4e8e\u5728\u201cbits\u201d\u4e2d\u8bbe\u5b9a\u6bcf\u4e00\u4f4d\uff0c\u4f60\u5f97\u5230\u4e00\u4e2a\u201con\u201d\u5b57\u7b26\u4e32\uff0c\u5e76\u4e14\u5bf9\u4e8e\u6bcf\u4e2a\u590d\u4f4d(reset)\u7684\u4f4d\uff0c\u4f60\u5f97\u5230\u4e00\u4e2a\u201coff\u201d\u5b57\u7b26\u4e32\u3002\u6bcf\u4e2a\u5b57\u7b26\u4e32\u7528\u201cseparator\u201d\u5206\u9694(\u7f3a\u7701\u201c,\u201d)\uff0c\u5e76\u4e14\u53ea\u6709\u201cbits\u201d\u7684\u201cnumber_of_bits\u201d (\u7f3a\u770164)\u4f4d\u88ab\u4f7f\u7528\u3002
\nmysql> select EXPORT_SET(5,’Y’,’N’,’,’,4)
\n\u00a0 -> Y,N,Y,N
\nLCASE(str)
\n\u3000
\nLOWER(str)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u6839\u636e\u5f53\u524d\u5b57\u7b26\u96c6\u6620\u5c04(\u7f3a\u7701\u662fISO-8859-1 Latin1)\u628a\u6240\u6709\u7684\u5b57\u7b26\u6539\u53d8\u6210\u5c0f\u5199\u3002\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nmysql> select LCASE(‘QUADRATICALLY’);
\n\u00a0 -> ‘quadratically’
\n\u00a0UCASE(str)
\n\u3000
\nUPPER(str)<\/strong>
\n\u8fd4\u56de\u5b57\u7b26\u4e32str\uff0c\u6839\u636e\u5f53\u524d\u5b57\u7b26\u96c6\u6620\u5c04(\u7f3a\u7701\u662fISO-8859-1 Latin1)\u628a\u6240\u6709\u7684\u5b57\u7b26\u6539\u53d8\u6210\u5927\u5199\u3002\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nmysql> select UCASE(‘Hej’);
\n\u00a0 -> ‘HEJ’
\n\u8be5\u51fd\u6570\u5bf9\u591a\u5b57\u8282\u662f\u53ef\u9760\u7684\u3002
\nLOAD_FILE(file_name)<\/strong>
\n\u8bfb\u5165\u6587\u4ef6\u5e76\u4e14\u4f5c\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32\u8fd4\u56de\u6587\u4ef6\u5185\u5bb9\u3002\u6587\u4ef6\u5fc5\u987b\u5728\u670d\u52a1\u5668\u4e0a\uff0c\u4f60\u5fc5\u987b\u6307\u5b9a\u5230\u6587\u4ef6\u7684\u5b8c\u6574\u8def\u5f84\u540d\uff0c\u800c\u4e14\u4f60\u5fc5\u987b\u6709file\u6743\u9650\u3002\u6587\u4ef6\u5fc5\u987b\u6240\u6709\u5185\u5bb9\u90fd\u662f\u53ef\u8bfb\u7684\u5e76\u4e14\u5c0f\u4e8emax_allowed_packet\u3002\u5982\u679c\u6587\u4ef6\u4e0d\u5b58\u5728\u6216\u7531\u4e8e\u4e0a\u9762\u539f\u56e0\u4e4b\u4e00\u4e0d\u80fd\u88ab\u8bfb\u51fa\uff0c\u51fd\u6570\u8fd4\u56deNULL\u3002
\nmysql> UPDATE table_name
\n\u00a0 SET blob_column=LOAD_FILE(“\/tmp\/picture”)
\n\u00a0 WHERE id=1;<\/p>\n

MySQL\u5fc5\u8981\u65f6\u81ea\u52a8\u53d8\u6362\u6570\u5b57\u4e3a\u5b57\u7b26\u4e32\uff0c\u5e76\u4e14\u53cd\u8fc7\u6765\u4e5f\u5982\u6b64\uff1a<\/p>\n

mysql> SELECT 1+”1″;
\n\u00a0 -> 2
\nmysql> SELECT CONCAT(2,’ test’);
\n\u00a0 -> ‘2 test’
\n\u5982\u679c\u4f60\u60f3\u8981\u660e\u786e\u5730\u53d8\u6362\u4e00\u4e2a\u6570\u5b57\u5230\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u628a\u5b83\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u5230CONCAT()\u3002<\/p>\n

\u5982\u679c\u5b57\u7b26\u4e32\u51fd\u6570\u63d0\u4f9b\u4e00\u4e2a\u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\u4f5c\u4e3a\u53c2\u6570\uff0c\u7ed3\u679c\u5b57\u7b26\u4e32\u4e5f\u662f\u4e00\u4e2a\u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\u3002\u88ab\u53d8\u6362\u5230\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u6570\u5b57\u88ab\u5f53\u4f5c\u662f\u4e00\u4e2a\u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\u3002\u8fd9\u4ec5\u5f71\u54cd\u6bd4\u8f83\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u5bf9\u4e8e\u9488\u5bf9\u5b57\u7b26\u4e32\u4f4d\u7f6e\u7684\u64cd\u4f5c\uff0c\u7b2c\u4e00\u4e2a\u4f4d\u7f6e\u88ab\u6807\u8bb0\u4e3a1\u3002 ASCII(st…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-288","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/posts\/288","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/comments?post=288"}],"version-history":[{"count":1,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/posts\/288\/revisions"}],"predecessor-version":[{"id":321,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/posts\/288\/revisions\/321"}],"wp:attachment":[{"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/media?parent=288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/categories?post=288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/elon.852128.com\/blog\/wp-json\/wp\/v2\/tags?post=288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}