¾µäSQLÓï¾ä
1,SELECT *,CASE OrderStatus WHEN 1 THEN 'δ´¦Àí' when 2 THEN 'Ëø¶¨' when
3 THEN 'ÒѳöƱ' ELSE '¹ýÆÚ' END
from dbo.T_OrderItem
2,
SELECT *,CAST(ROUND(CAST (HostWin AS FLOAT)/(HostWin+HostDraw+HostBear),2)*100 AS varchar)+'%' AS HostWinRate,
CAST(ROUND(CAST (HostDraw AS FLOAT)/(HostWin+HostDraw+HostBear),2)*100 AS varchar)+'%'AS HostDrawRate,
CAST(ROUND(CAST (HostBear AS FLOAT)/(HostWin+HostDraw+HostBear),2)*100 AS varchar)+'%' AS HostBearRate from V_DoubleBuy
?Convert.ToDateTime(row.ItemArray[0])
Ïà¹ØÎĵµ£º
´Ó8iµ½10g£¬Oracle²»¶Ï½ø»¯×Ô¼ºµÄSQL TuningÖÇÄÜ£¬Ò»Ð©Ãؼ®¼¶µÄÓÅ»¯¿Ú¾÷ÒѾʧЧ¡£
µ«ÎÒϲ»¶Ê§Ð§£¬²»Óüǿھ÷£¬²Ù¸öToad for Oracle Xpert
£¬°´ÕÕ´ó·½ÏòÊæÊæ·þ·þµÄ
µ÷ÓŲÅÊǰ®×öµÄÊÂÇé¡£
1.Excution Plan
Excution
PlanÊÇ×î»ù±¾µÄµ÷ÓŸÅÄ²»¹ÜÄãµÄµ÷ÓÅ´µµÃÈçºÎÌ ......
Äãд¹ýÒ»ÌõsqlÓï¾äÀ´ÐÞ¸ÄÁ½¸ö±íµÄÊý¾ÝÂð£¿
UPDATE test.table1 t1,test.table2 t2 SET t1.aa='a',t1.bb='b',t2.cc='c',WHERE t1.u_id=t2.u_id AND t1.u_id='1' £»
table1µÄu_idºÍtable2µÄu_idÊÇÖ÷Íâ¼ü¹ØÏµ ......
Sql³£ÓÃÓï·¨ÏÂÁÐÓï¾ä²¿·ÖÊÇMssqlÓï¾ä£¬²»¿ÉÒÔÔÚaccessÖÐʹÓá£
SQL·ÖÀࣺ
DDL—Êý¾Ý¶¨ÒåÓïÑÔ(CREATE£¬ALTER£¬DROP£¬DECLARE)
DML—Êý¾Ý²Ù×ÝÓïÑÔ(SELECT£¬DELETE£¬UPDATE£¬INSERT)
DCL—Êý¾Ý¿ØÖÆÓïÑÔ(GRANT£¬REVOKE£¬COMMIT£¬ROLLBACK) Ê×ÏÈ,¼òÒª½éÉÜ»ù´¡Óï¾ä£º
1¡¢ËµÃ÷£º´´½¨Êý¾Ý¿â
CREATE ......
1.ÓÃÒ»ÌõSqlÓï¾ä²éѯ³öÿÃŹ¦¿Î¶¼´óÓÚ80·ÖµÄѧÉúÐÕÃû
Name
Class
Result
ÕÅÈý
ÓïÎÄ
56
ÕÅÈý
Êýѧ
88
ÀîËÄ
ÓïÎÄ
92
ÀîËÄ
Êýѧ
100
ÍõÎå
ÓïÎÄ
88
ÍõÎå
Êýѧ
99
ÍõÎå
Ó¢Óï
99
-------------------------------------------------------------------------------
´ð°¸£º
SELECT DISTINCT nam ......
´Ó¹ÙÍøÏÂÔØSQL Server 2008µÄ180ÌìÊÔÓðæÆäʵÓëÕýʽ°æÄÚÈÝÊÇ»ù±¾ÏàͬµÄ£¬Î¨Ò»µÄÇø±ð¾ÍÔÚÓÚ°²×°ÅäÖÃÎļþÖÐËù°üº¬µÄkey¡£¸÷ÖÖ°æ±¾µÄSQL ServerÔÚ½øÐе½ÕâÒ»²½Ö®Ç°¶¼ÊÇÍêȫһÑùµÄ£º
Microsoft® SQL Server® 2008 Enterprise Evaluation£º¿ª·¢ÈËÔ±ÊÔÓÃÌåÑé
Microsoft® SQL Server® 2008 Enterprise Evaluatio ......