SQLÀúÊ·ÓëʵÏÖ
ÔÚ20ÊÀ¼Í70Äê´ú³õÆÚ£¬IBMÑо¿Ô±E. F. Codd²©Ê¿¿ª´´ÐÔµØÑо¿¿ª·¢Á˹ØϵÊý¾ÝÄ£ÐͲúÆ·SEQUEL£¬¼´½á¹¹»¯Ó¢Óï²éѯÓïÑÔ£¨Structured English Query Language£©¡£SEQUEL×îÖÕ±ä³ÉÁËSQL£¬»ò½á¹¹»¯²éѯÓïÑÔ£¨Structured Query Language£¬SQL£©¡£
IBM¼°ÆäËû¹ØϵÊý¾Ý¿âµÄ¿ª·¢³§É̶¼Ï£ÍûÓÐÒ»Ì×ÄÜ·ÃÎʲ¢²Ù×ݹØϵÊý¾Ý¿âµÄ±ê×¼»¯·½·¨¡£ËäÈ»IBMÊ×´´Á˹ØϵÊý¾Ý¿âÀíÂÛ£¬µ«OracleÊǵÚÒ»¼ÒÔÚÊг¡ÉÏÍƳö¸Ã¼¼ÊõµÄ¹«Ë¾¡£Ëæ×Åʱ¼äµÄÁ÷ÊÅ£¬SQLÔÚÊг¡Éϵõ½Á˲»´íµÄ·´Ï죬ÕâÒýÆðÁËÃÀ¹ú¹ú¼Ò±ê×¼¾Ö£¨American National Standards Institute£¬ANSI£©µÄ¹Ø×¢£¬²¢·Ö±ðÔÚ1986Äê¡¢1989Äê¡¢1992Äê¡¢2003Äê¼°2006Äê·¢²¼ÁËSQL±ê×¼¡£±¾ÎÄÊÊÓÃÓÚANSI 2003±ê×¼£¬ÒòΪANSI 2006±ê×¼´¦ÀíSQLÔªËØÒѳ¬³öÁ˱¾ÊéµÄÃüÁΧ¡££¨ÊµÖÊÉÏ£¬SQL2006±ê×¼ÃèÊöÁËÔÚSQLÖÐÈçºÎʹÓÃXML¡££©
×Ô1986ÄêÒÔÀ´£¬ÒÑÓжàÖÖ¿Éʹ³ÌÐòÔ±¼°¿ª·¢Õß·ÃÎʲ¢²Ù×ݹØϵÊý¾ÝµÄÓïÑÔ¡£µ«ÊÇ£¬ºÜÉÙÓÐÏñSQLÕâôºÃѧ»ò±»¹ã·ºµØ»ñµÃÈÏͬµÄÒ»ÃÅÓïÑÔ¡£SQLÈóÌÐòÔ±¼°¹ÜÀíÕßÖ»Ðëѧϰµ¥Ò»ÓïÑÔ£¬ÉÔ΢×÷µãµ÷Õû£¬±ã¿ÉÒÔ°ÑËü¹ã·ºÓ¦Óõ½¶àÖÖÊý¾Ý¿âƽ̨¡¢Ó¦ÓóÌÐò¼°²úÆ·ÖС£
¡¶SQL¼¼ÊõÊֲᣨµÚÈý°æ£©¡·½²ÊöÁËÎåÖÖSQL2003£¨SQL3£©µÄ³£¼ûʵÏÖ£º
1.1 ¹ØϵģÐÍÓëANSI SQL
¹ØϵÊý¾Ý¿â¹ÜÀíϵͳ£¨Relational database management systems£¬RDBMSs£©£¬Èç±¾ÊéËù½éÉܵģ¬ÊÇÈ«ÊÀ½çÐÅϢϵͳµÄÖ÷ÒªÇý¶¯ÒýÇ棬ÓÈÆäÔÚÍøÂçÓ¦Óü°·Ö²¼Ê½¿Í»§¶Ë/·þÎñÆ÷£¨client/server£©´¦ÀíϵͳÖнÏΪ³£¼û¡£ËüÃÇ¿ÉÈÃÐí¶àÓû§¿ìËÙ²¢Í¬Ê±·ÃÎÊ¡¢´´½¨¡¢±à¼¼°²Ù×ÝÊý¾Ý£¬Ò²¿ÉÈóÌÐò¿ª·¢Õß±àдÓÐÓõÄÓ¦ÓóÌÐòÒÔ±ã·ÃÎÊ×ÊÔ´£¬»¹¿ÉÈùÜÀíÕ߶Ô×éÖ¯ºÃµÄÊý¾ÝÔ´¼ÓÒÔά»¤¡¢±£»¤¼°×îÓÅ»¯¡£
RDBMSÊÇÒ»Ì×ϵͳ£¬ËüµÄÓû§Êý¾ÝΪ±Ë´Ë»¥ÓйØÁªµÄ±í¼¯ºÏ£¬¹ØÁªÊÇÓÉÓÚËüÃÇÓй²Í¬µÄÊý¾ÝÖµ¡£Êý¾Ý´æ´¢ÔÚÓÉÊý¾ÝÐУ¨row£©ºÍÊý¾ÝÁУ¨column£©×é³ÉµÄÊý¾Ý±í£¨table£©ÖС£Èç¹û¶ÀÁ¢µÄÊý¾Ý±í¼äÓÐΨһ±êʶµÄÊý¾ÝÁУ¨¼´¼ü£©£¬ÔòËü¿É±íʾ¹²ÓеÄÊý¾ÝÖµ£¬ÕâЩÊý¾Ý±íÒ²Äܱ˴ËÏàÁª£¨»òÕß˵²úÉú¹ØÁª£©¡£1970Äê6Ô£¬E. F. Codd·¢±íÔÚ¡¶ÃÀ¹ú¼ÆËã»úлáͨѶ¡·£¨Communications of the ACM£©ÉϵĹؼüÐÔÂÛÎÄ¡¶A Relational Model of Data for Large Shared Data Banks¡·ÖÐÊ×´ÎÌá³ö¹ØϵÊý¾Ý¿âÀíÂÛ¡£ÔÚCoddµÄйØϵÊý¾ÝÄ£ÐÍÖУ¬Êý¾ÝÒԽṹʽ£¨ÐγÉÓÉÊý¾ÝÐкÍÊý¾ÝÁÐ×é³ÉµÄÊý¾Ý±í£©³ÊÏÖ£¬¿ÉÒÔʹÓÃÑ¡Ôñ¡¢Í¶Ó°¼°Á´½ÓµÈ²Ù×÷·½Ê½¹ÜÀí£¬²¢ÇÒÓÉÓÚ¼üÖµµÄÍêÕûÐÔ¼°²ÎÕÕÍêÕûÐÔµÈÔÔò¶øʹµÃÊý¾Ý¾ßÓÐÒ»ÖÂÐÔ¡£Codd»¹Ìá³öÁ
Ïà¹ØÎĵµ£º
ÓÃSQLÓï¾äÌí¼Óɾ³ýÐÞ¸Ä×Ö¶Î
1.Ôö¼Ó×Ö¶Î
alter table docdsp add dspcode char(200)
alter table tbl add meet_group int2
2.ɾ³ý×Ö¶Î
ALTER TABLE table_NAME DROP COLUMN column_NAME
3.ÐÞ¸Ä×Ö¶ÎÀàÐÍ
&nbs ......
Èç¹ûÊÇÀàËÆ"select * from user where uid="+uid +" and pwd="+pwd ºÜÈÝÒ׳öÎÊÌâ
ʹÓà SQLParamenter
°ÑÄãµÄSQLÓï¾äд³É ÀàËÆ´æ´¢¹ý³Ì ......
1¡¢ SQL×¢Èë¹¥»÷µÄ±¾ÖÊ£ºÈÿͻ§¶Ë´«µÝ¹ýÈ¥µÄ×Ö·û´®±ä³ÉSQLÓï¾ä£¬¶øÇÒÄܹ»±»Ö´ÐС£
2¡¢ ÿ¸ö³ÌÐòÔ±¶¼±ØÐë¼ç¸ºÆð·ÀÖ¹SQL×¢Èë¹¥»÷µÄÔðÈΡ£
¡¡¡¡ËµÆð·ÀÖ¹SQL×¢Èë¹¥»÷£¬¸Ð¾õºÜÓôÃÆ£¬Õâô¶àÄêÁË´ó¼ÒÒ»Ö±ÔÚÌÖÂÛ£¬Ò²Ò»Ö±ÔÚÕùÂÛ£¬¿ÉÊǵ½ÁËÏÖÔÚËƺõ»¹ÊÇûÓж¨ÂÛ¡£µ±²»ÖªµÀ×¢ÈëÔÀíµÄʱºò»á¾õµÃºÜÉñÆ棬Ôõô¾Í±»×¢ÈëÁËÄØ£¿ ......
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, Grids, DBGrids, DB, ADODB,comobj, OleServer,
ExcelXP;
type
TForm1 = class(TForm)
ADOConn: TADOConnection;
& ......