{"id":23,"date":"2019-07-07T11:03:42","date_gmt":"2019-07-07T03:03:42","guid":{"rendered":"http:\/\/22pig.com\/?p=23"},"modified":"2019-07-07T11:03:42","modified_gmt":"2019-07-07T03:03:42","slug":"sql-server%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"http:\/\/22pig.com\/?p=23","title":{"rendered":"sql server\u5e38\u7528\u51fd\u6570"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u4e00\u3001\u5b57\u7b26\u8f6c\u6362\u51fd\u6570<br>\n1\u3001ASCII()<br>\n\u8fd4\u56de\u5b57\u7b26\u8868\u8fbe\u5f0f\u6700\u5de6\u7aef\u5b57\u7b26\u7684ASCII \u7801\u503c\u3002\u5728ASCII\uff08\uff09\u51fd\u6570\u4e2d\uff0c\u7eaf\u6570\u5b57\u7684\u5b57\u7b26\u4e32\u53ef\u4e0d\u7528\u2018\u2019\u62ec\u8d77\u6765\uff0c\u4f46\u542b\u5176\u5b83\u5b57\u7b26\u7684\u5b57\u7b26\u4e32\u5fc5\u987b\u7528\u2018\u2019\u62ec\u8d77\u6765\u4f7f\u7528\uff0c\u5426\u5219\u4f1a\u51fa\u9519\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001CHAR()<br>\n\u5c06ASCII \u7801\u8f6c\u6362\u4e3a\u5b57\u7b26\u3002\u5982\u679c\u6ca1\u6709\u8f93\u51650 ~ 255 \u4e4b\u95f4\u7684ASCII \u7801\u503c\uff0cCHAR\uff08\uff09 \u8fd4\u56deNULL \u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001LOWER()\u548cUPPER()<br>\nLOWER()\u5c06\u5b57\u7b26\u4e32\u5168\u90e8\u8f6c\u4e3a\u5c0f\u5199\uff1bUPPER()\u5c06\u5b57\u7b26\u4e32\u5168\u90e8\u8f6c\u4e3a\u5927\u5199\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">4\u3001STR()<br>\n\u628a\u6570\u503c\u578b\u6570\u636e\u8f6c\u6362\u4e3a\u5b57\u7b26\u578b\u6570\u636e\u3002<br>\nSTR ([\uff0clength[\uff0c ]])<br>\nlength \u6307\u5b9a\u8fd4\u56de\u7684\u5b57\u7b26\u4e32\u7684\u957f\u5ea6\uff0cdecimal \u6307\u5b9a\u8fd4\u56de\u7684\u5c0f\u6570\u4f4d\u6570\u3002\u5982\u679c\u6ca1\u6709\u6307\u5b9a\u957f\u5ea6\uff0c\u7f3a\u7701\u7684length \u503c\u4e3a10\uff0c decimal \u7f3a\u7701\u503c\u4e3a0\u3002<br>\n\u5f53length \u6216\u8005decimal \u4e3a\u8d1f\u503c\u65f6\uff0c\u8fd4\u56deNULL\uff1b<br>\n\u5f53length \u5c0f\u4e8e\u5c0f\u6570\u70b9\u5de6\u8fb9\uff08\u5305\u62ec\u7b26\u53f7\u4f4d\uff09\u7684\u4f4d\u6570\u65f6\uff0c\u8fd4\u56delength \u4e2a*\uff1b<br>\n\u5148\u670d\u4ecelength \uff0c\u518d\u53d6decimal \uff1b<br>\n\u5f53\u8fd4\u56de\u7684\u5b57\u7b26\u4e32\u4f4d\u6570\u5c0f\u4e8elength \uff0c\u5de6\u8fb9\u8865\u8db3\u7a7a\u683c\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e8c\u3001\u53bb\u7a7a\u683c\u51fd\u6570<br>\n1\u3001LTRIM() \u628a\u5b57\u7b26\u4e32\u5934\u90e8\u7684\u7a7a\u683c\u53bb\u6389\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001RTRIM() \u628a\u5b57\u7b26\u4e32\u5c3e\u90e8\u7684\u7a7a\u683c\u53bb\u6389\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e09\u3001\u53d6\u5b50\u4e32\u51fd\u6570<br>\n1\u3001left() <br>\nLEFT (\uff0c )<br>\n\u8fd4\u56decharacter_expression \u5de6\u8d77 integer_expression \u4e2a\u5b57\u7b26\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001RIGHT() <br>\nRIGHT (\uff0c )<br>\n\u8fd4\u56decharacter_expression \u53f3\u8d77 integer_expression \u4e2a\u5b57\u7b26\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001SUBSTRING()<br>\nSUBSTRING (\uff0c \uff0c length)<br>\n\u8fd4\u56de\u4ece\u5b57\u7b26\u4e32\u5de6\u8fb9\u7b2cstarting_ position \u4e2a\u5b57\u7b26\u8d77length\u4e2a\u5b57\u7b26\u7684\u90e8\u5206\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u56db\u3001\u5b57\u7b26\u4e32\u6bd4\u8f83\u51fd\u6570<br>\n1\u3001CHARINDEX()<br>\n\u8fd4\u56de\u5b57\u7b26\u4e32\u4e2d\u67d0\u4e2a\u6307\u5b9a\u7684\u5b50\u4e32\u51fa\u73b0\u7684\u5f00\u59cb\u4f4d\u7f6e\u3002<br>\nCHARINDEX (&lt;\u2019substring_expression\u2019&gt;\uff0c )<br>\n\u5176\u4e2dsubstring _expression \u662f\u6240\u8981\u67e5\u627e\u7684\u5b57\u7b26\u8868\u8fbe\u5f0f\uff0cexpression \u53ef\u4e3a\u5b57\u7b26\u4e32\u4e5f\u53ef\u4e3a\u5217\u540d\u8868\u8fbe\u5f0f\u3002\u5982\u679c\u6ca1\u6709\u53d1\u73b0\u5b50\u4e32\uff0c\u5219\u8fd4\u56de0 \u503c\u3002<br>\n\u6b64\u51fd\u6570\u4e0d\u80fd\u7528\u4e8eTEXT \u548cIMAGE \u6570\u636e\u7c7b\u578b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001PATINDEX()<br>\n\u8fd4\u56de\u5b57\u7b26\u4e32\u4e2d\u67d0\u4e2a\u6307\u5b9a\u7684\u5b50\u4e32\u51fa\u73b0\u7684\u5f00\u59cb\u4f4d\u7f6e\u3002<br>\nPATINDEX (&lt;\u2019%substring _expression%\u2019&gt;\uff0c )\u5176\u4e2d\u5b50\u4e32\u8868\u8fbe\u5f0f\u524d\u540e\u5fc5\u987b\u6709\u767e\u5206\u53f7\u201c%\u201d\u5426\u5219\u8fd4\u56de\u503c\u4e3a0\u3002<br>\n\u4e0eCHARINDEX \u51fd\u6570\u4e0d\u540c\u7684\u662f\uff0cPATINDEX\u51fd\u6570\u7684\u5b50\u4e32\u4e2d\u53ef\u4ee5\u4f7f\u7528\u901a\u914d\u7b26\uff0c\u4e14\u6b64\u51fd\u6570\u53ef\u7528\u4e8eCHAR\u3001 VARCHAR \u548cTEXT \u6570\u636e\u7c7b\u578b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e94\u3001\u5b57\u7b26\u4e32\u64cd\u4f5c\u51fd\u6570<br>\n1\u3001QUOTENAME()<br>\n\u8fd4\u56de\u88ab\u7279\u5b9a\u5b57\u7b26\u62ec\u8d77\u6765\u7684\u5b57\u7b26\u4e32\u3002<br>\nQUOTENAME (&lt;\u2019character_expression\u2019&gt;[\uff0c quote_ character]) \u5176\u4e2dquote_ character \u6807\u660e\u62ec\u5b57\u7b26\u4e32\u6240\u7528\u7684\u5b57\u7b26\uff0c\u7f3a\u7701\u503c\u4e3a\u201c[]\u201d\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001REPLICATE()<br>\n\u8fd4\u56de\u4e00\u4e2a\u91cd\u590dcharacter_expression \u6307\u5b9a\u6b21\u6570\u7684\u5b57\u7b26\u4e32\u3002<br>\nREPLICATE (character_expression integer_expression) \u5982\u679cinteger_expression \u503c\u4e3a\u8d1f\u503c\uff0c\u5219\u8fd4\u56deNULL \u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001REVERSE()<br>\n\u5c06\u6307\u5b9a\u7684\u5b57\u7b26\u4e32\u7684\u5b57\u7b26\u6392\u5217\u987a\u5e8f\u98a0\u5012\u3002<br>\nREVERSE () \u5176\u4e2dcharacter_expression \u53ef\u4ee5\u662f\u5b57\u7b26\u4e32\u3001\u5e38\u6570\u6216\u4e00\u4e2a\u5217\u7684\u503c\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">4\u3001REPLACE()<br>\n\u8fd4\u56de\u88ab\u66ff\u6362\u4e86\u6307\u5b9a\u5b50\u4e32\u7684\u5b57\u7b26\u4e32\u3002<br>\nREPLACE (\uff0c \uff0c ) \u7528string_expression3 \u66ff\u6362\u5728string_expression1 \u4e2d\u7684\u5b50\u4e32string_expression2\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">5\u3001SPACE()<br>\n\u8fd4\u56de\u4e00\u4e2a\u6709\u6307\u5b9a\u957f\u5ea6\u7684\u7a7a\u767d\u5b57\u7b26\u4e32\u3002<br>\nSPACE () \u5982\u679cinteger_expression \u503c\u4e3a\u8d1f\u503c\uff0c\u5219\u8fd4\u56deNULL \u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">6\u3001STUFF()<br>\n\u7528\u53e6\u4e00\u5b50\u4e32\u66ff\u6362\u5b57\u7b26\u4e32\u6307\u5b9a\u4f4d\u7f6e\u3001\u957f\u5ea6\u7684\u5b50\u4e32\u3002<br>\nSTUFF (\uff0c \uff0c \uff0c)\u5982\u679c\u8d77\u59cb\u4f4d\u7f6e\u4e3a\u8d1f\u6216\u957f\u5ea6\u503c\u4e3a\u8d1f\uff0c\u6216\u8005\u8d77\u59cb\u4f4d\u7f6e\u5927\u4e8echaracter_expression1 \u7684\u957f\u5ea6\uff0c\u5219\u8fd4\u56deNULL \u503c\u3002\u5982\u679clength \u957f\u5ea6\u5927\u4e8echaracter_expression1 \u4e2d start_ position \u4ee5\u53f3\u7684\u957f\u5ea6\uff0c\u5219character_expression1 \u53ea\u4fdd\u7559\u9996\u5b57\u7b26\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u516d\u3001\u6570\u636e\u7c7b\u578b\u8f6c\u6362\u51fd\u65701\u3001CAST()CAST ( AS [ length ])2\u3001CONVERT()CONVERT ([ length ]\uff0c  [\uff0c style])<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1\uff09data_type\u4e3aSQL Server\u7cfb\u7edf\u5b9a\u4e49\u7684\u6570\u636e\u7c7b\u578b\uff0c\u7528\u6237\u81ea\u5b9a\u4e49\u7684\u6570\u636e\u7c7b\u578b\u4e0d\u80fd\u5728\u6b64\u4f7f\u7528\u3002<br>\n2\uff09length\u7528\u4e8e\u6307\u5b9a\u6570\u636e\u7684\u957f\u5ea6\uff0c\u7f3a\u7701\u503c\u4e3a30\u3002<br>\n3\uff09\u628aCHAR\u6216VARCHAR\u7c7b\u578b\u8f6c\u6362\u4e3a\u8bf8\u5982INT\u6216SAMLLINT\u8fd9\u6837\u7684INTEGER\u7c7b\u578b\u3001\u7ed3\u679c\u5fc5\u987b\u662f\u5e26\u6b63\u53f7\u6216\u8d1f\u53f7\u7684\u6570\u503c\u3002<br>\n4\uff09TEXT\u7c7b\u578b\u5230CHAR\u6216VARCHAR\u7c7b\u578b\u8f6c\u6362\u6700\u591a\u4e3a8000\u4e2a\u5b57\u7b26\uff0c\u5373CHAR\u6216VARCHAR\u6570\u636e\u7c7b\u578b\u662f\u6700\u5927\u957f\u5ea6\u3002<br>\n5\uff09IMAGE\u7c7b\u578b\u5b58\u50a8\u7684\u6570\u636e\u8f6c\u6362\u5230BINARY\u6216VARBINARY\u7c7b\u578b\uff0c\u6700\u591a\u4e3a8000\u4e2a\u5b57\u7b26\u3002<br>\n6\uff09\u628a\u6574\u6570\u503c\u8f6c\u6362\u4e3aMONEY\u6216SMALLMONEY\u7c7b\u578b\uff0c\u6309\u5b9a\u4e49\u7684\u56fd\u5bb6\u7684\u8d27\u5e01\u5355\u4f4d\u6765\u5904\u7406\uff0c\u5982\u4eba\u6c11\u5e01\u3001\u7f8e\u5143\u3001\u82f1\u9551\u7b49\u3002<br>\n7\uff09BIT\u7c7b\u578b\u7684\u8f6c\u6362\u628a\u975e\u96f6\u503c\u8f6c\u6362\u4e3a1\uff0c\u5e76\u4ecd\u4ee5BIT\u7c7b\u578b\u5b58\u50a8\u3002<br>\n8\uff09\u8bd5\u56fe\u8f6c\u6362\u5230\u4e0d\u540c\u957f\u5ea6\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4f1a\u622a\u77ed\u8f6c\u6362\u503c\u5e76\u5728\u8f6c\u6362\u503c\u540e\u663e\u793a\u201c+\u201d\uff0c\u4ee5\u6807\u8bc6\u53d1\u751f\u4e86\u8fd9\u79cd\u622a\u65ad\u3002<br>\n9\uff09\u7528CONVERT\uff08\uff09\u51fd\u6570\u7684style \u9009\u9879\u80fd\u4ee5\u4e0d\u540c\u7684\u683c\u5f0f\u663e\u793a\u65e5\u671f\u548c\u65f6\u95f4\u3002style \u662f\u5c06DATATIME \u548cSMALLDATETIME \u6570\u636e\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u65f6\u6240\u9009\u7528\u7684\u7531SQL Server \u7cfb\u7edf\u63d0\u4f9b\u7684\u8f6c\u6362\u6837\u5f0f\u7f16\u53f7\uff0c\u4e0d\u540c\u7684\u6837\u5f0f\u7f16\u53f7\u6709\u4e0d\u540c\u7684\u8f93\u51fa\u683c\u5f0f\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e03\u3001\u65e5\u671f\u51fd\u6570<br>\n1\u3001day(date_expression) \u8fd4\u56dedate_expression\u4e2d\u7684\u65e5\u671f\u503c<br>\n2\u3001month(date_expression)\u8fd4\u56dedate_expression\u4e2d\u7684\u6708\u4efd\u503c<br>\n3\u3001year(date_expression)\u8fd4\u56dedate_expression\u4e2d\u7684\u5e74\u4efd\u503c<br>\n4\u3001DATEADD()DATEADD (\uff0c \uff0c )\u8fd4\u56de\u6307\u5b9a\u65e5\u671fdate \u52a0\u4e0a\u6307\u5b9a\u7684\u989d\u5916\u65e5\u671f\u95f4\u9694number \u4ea7\u751f\u7684\u65b0\u65e5\u671f\u3002<br>\n5\u3001DATEDIFF()DATEDIFF (\uff0c \uff0c )\u8fd4\u56de\u4e24\u4e2a\u6307\u5b9a\u65e5\u671f\u5728datepart \u65b9\u9762\u7684\u4e0d\u540c\u4e4b\u5904\uff0c\u5373date2 \u8d85\u8fc7date1\u7684\u5dee\u8ddd\u503c\uff0c\u5176\u7ed3\u679c\u503c\u662f\u4e00\u4e2a\u5e26\u6709\u6b63\u8d1f\u53f7\u7684\u6574\u6570\u503c\u3002<br>\n6\u3001DATENAME()DATENAME (\uff0c )\u4ee5\u5b57\u7b26\u4e32\u7684\u5f62\u5f0f\u8fd4\u56de\u65e5\u671f\u7684\u6307\u5b9a\u90e8\u5206\u6b64\u90e8\u5206\u3002\u7531datepart \u6765\u6307\u5b9a\u3002<br>\n7\u3001DATEPART()DATEPART (\uff0c )\u4ee5\u6574\u6570\u503c\u7684\u5f62\u5f0f\u8fd4\u56de\u65e5\u671f\u7684\u6307\u5b9a\u90e8\u5206\u3002\u6b64\u90e8\u5206\u7531datepart \u6765\u6307\u5b9a\u3002DATEPART (dd\uff0c date) \u7b49\u540c\u4e8eDAY (date)DATEPART (mm\uff0c date) \u7b49\u540c\u4e8eMONTH (date)DATEPART (yy\uff0c date) \u7b49\u540c\u4e8eYEAR (date)<br>\n8\u3001GETDATE()\u4ee5DATETIME \u7684\u7f3a\u7701\u683c\u5f0f\u8fd4\u56de\u7cfb\u7edf\u5f53\u524d\u7684\u65e5\u671f\u548c\u65f6\u95f4\u3002<br>\n9\u3001Sql Server \u4e2d\u4e00\u4e2a\u975e\u5e38\u5f3a\u5927\u7684\u65e5\u671f\u683c\u5f0f\u5316\u51fd\u6570<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Select CONVERT(varchar(100), GETDATE(), 0): 05 16 2006 10:57AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 1): 05\/16\/06<br>\nSelect CONVERT(varchar(100), GETDATE(), 2): 06.05.16<br>\nSelect CONVERT(varchar(100), GETDATE(), 3): 16\/05\/06<br>\nSelect CONVERT(varchar(100), GETDATE(), 4): 16.05.06<br>\nSelect CONVERT(varchar(100), GETDATE(), 5): 16-05-06<br>\nSelect CONVERT(varchar(100), GETDATE(), 6): 16 05 06<br>\nSelect CONVERT(varchar(100), GETDATE(), 7): 05 16, 06<br>\nSelect CONVERT(varchar(100), GETDATE(), 8): 10:57:46<br>\nSelect CONVERT(varchar(100), GETDATE(), 9): 05 16 2006 10:57:46:827AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 10): 05-16-06<br>\nSelect CONVERT(varchar(100), GETDATE(), 11): 06\/05\/16<br>\nSelect CONVERT(varchar(100), GETDATE(), 12): 060516<br>\nSelect CONVERT(varchar(100), GETDATE(), 13): 16 05 2006 10:57:46:937<br>\nSelect CONVERT(varchar(100), GETDATE(), 14): 10:57:46:967<br>\nSelect CONVERT(varchar(100), GETDATE(), 20): 2006-05-16 10:57:47<br>\nSelect CONVERT(varchar(100), GETDATE(), 21): 2006-05-16 10:57:47.157<br>\nSelect CONVERT(varchar(100), GETDATE(), 22): 05\/16\/06 10:57:47 AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 23): 2006-05-16<br>\nSelect CONVERT(varchar(100), GETDATE(), 24): 10:57:47<br>\nSelect CONVERT(varchar(100), GETDATE(), 25): 2006-05-16 10:57:47.250<br>\nSelect CONVERT(varchar(100), GETDATE(), 100): 05 16 2006 10:57AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 101): 05\/16\/2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 102): 2006.05.16<br>\nSelect CONVERT(varchar(100), GETDATE(), 103): 16\/05\/2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 104): 16.05.2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 105): 16-05-2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 106): 16 05 2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 107): 05 16, 2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 108): 10:57:49<br>\nSelect CONVERT(varchar(100), GETDATE(), 109): 05 16 2006 10:57:49:437AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 110): 05-16-2006<br>\nSelect CONVERT(varchar(100), GETDATE(), 111): 2006\/05\/16<br>\nSelect CONVERT(varchar(100), GETDATE(), 112): 20060516<br>\nSelect CONVERT(varchar(100), GETDATE(), 113): 16 05 2006 10:57:49:513<br>\nSelect CONVERT(varchar(100), GETDATE(), 114): 10:57:49:547<br>\nSelect CONVERT(varchar(100), GETDATE(), 120): 2006-05-16 10:57:49<br>\nSelect CONVERT(varchar(100), GETDATE(), 121): 2006-05-16 10:57:49.700<br>\nSelect CONVERT(varchar(100), GETDATE(), 126): 2006-05-16T10:57:49.827<br>\nSelect CONVERT(varchar(100), GETDATE(), 130): 18 ???? ?????? 1427 10:57:49:907AM<br>\nSelect CONVERT(varchar(100), GETDATE(), 131): 18\/04\/1427 10:57:49:920AM<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e00\u3001\u5b57\u7b26\u8f6c\u6362\u51fd\u6570 1\u3001ASCII() \u8fd4\u56de\u5b57\u7b26\u8868\u8fbe\u5f0f\u6700\u5de6\u7aef\u5b57\u7b26\u7684ASCII \u7801\u503c\u3002\u5728ASCII\uff08\uff09\u51fd\u6570\u4e2d\uff0c\u7eaf\u6570\u5b57\u7684\u5b57\u7b26\u4e32\u53ef\u4e0d\u7528\u2018\u2019\u62ec\u8d77\u6765\uff0c\u4f46\u542b\u5176\u5b83\u5b57\u7b26\u7684\u5b57\u7b26\u4e32\u5fc5\u987b\u7528\u2018\u2019\u62ec\u8d77\u6765\u4f7f\u7528\uff0c\u5426\u5219\u4f1a\u51fa\u9519\u3002 2\u3001CHAR() \u5c06ASCII \u7801\u8f6c\u6362\u4e3a\u5b57\u7b26\u3002\u5982\u679c\u6ca1\u6709\u8f93\u51650 ~ 255 \u4e4b\u95f4\u7684ASCII \u7801\u503c\uff0cCHAR\uff08\uff09 \u8fd4\u56deNULL \u3002 3\u3001LOWER()\u548cUPPER() LOWER()\u5c06\u5b57\u7b26\u4e32\u5168\u90e8\u8f6c\u4e3a\u5c0f\u5199\uff1bUPPER()\u5c06\u5b57\u7b26\u4e32\u5168\u90e8\u8f6c\u4e3a\u5927\u5199\u3002 4\u3001STR() 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\u628a\u5b57\u7b26\u4e32\u5c3e\u90e8\u7684\u7a7a\u683c\u53bb\u6389\u3002 \u4e09\u3001\u53d6\u5b50\u4e32\u51fd\u6570 1\u3001left() LEFT (\uff0c ) \u8fd4\u56decharacter_expression \u5de6\u8d77 integer_expression \u4e2a\u5b57\u7b26\u3002 2\u3001RIGHT() RIGHT (\uff0c ) 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