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  ûÓÐ,ÓÃcase   when   À´´úÌæ¾ÍÐÐÁË.   
       
  ÀýÈç,ÏÂÃæµÄÓï¾äÏÔʾÖÐÎÄÄêÔ  
   
  select   getdate()   as   ÈÕÆÚ,case   month(getdate())  
  when   11   then   'ʮһ'  
  when   12   then   'Ê®¶þ'  
  else   substring('Ò»¶þÈýËÄÎåÁùÆ߰˾ÅÊ®',   month(getdate()),1)  
  end+'ÔÂ'   as   Ô·Ý
=====================================================================
CASE ¿ÉÄÜÊÇ SQL Öб»ÎóÓÃ×î¶àµÄ¹Ø¼ü×ÖÖ®Ò»¡£ËäÈ»Äã¿ÉÄÜÒÔÇ°ÓùýÕâ¸ö¹Ø¼ü×ÖÀ´´´½¨×ֶΣ¬µ«ÊÇËü»¹¾ßÓиü¶àÓ÷¨¡£ÀýÈ磬Äã¿ÉÒÔÔÚ WHERE ×Ó¾äÖÐʹÓà CASE¡£

Ê×ÏÈÈÃÎÒÃÇ¿´Ò»Ï CASE µÄÓï·¨¡£ÔÚÒ»°ãµÄ SELECT ÖУ¬ÆäÓï·¨ÈçÏ£º

SELECT <myColumnSpec> =
CASE
WHEN <A> THEN <somethingA>
WHEN <B> THEN <somethingB>
ELSE <somethingE>
END

ÔÚÉÏÃæµÄ´úÂëÖÐÐèÒªÓþßÌåµÄ²ÎÊý´úÌæ¼âÀ¨ºÅÖеÄÄÚÈÝ¡£ÏÂÃæÊÇÒ»¸ö¼òµ¥µÄÀý×Ó£º

USE pubs
GO
SELECT
     Title,
    'Price Range' =
    CASE
        WHEN price IS NULL THEN 'Unpriced'
        WHEN price < 10 THEN 'Bargain'
        WHEN price BETWEEN 10 and 20 THEN 'Average'
        ELSE 'Gift to impress relatives'
    END
from titles
ORDER BY price
GO

ÕâÊÇ CASE µÄµäÐÍÓ÷¨£¬µ«ÊÇʹÓà CASE Æäʵ¿ÉÒÔ×ö¸ü¶àµÄÊÂÇé¡£±È·½ËµÏÂÃæµÄ GROUP BY ×Ó¾äÖÐµÄ CASE£º

SELECT 'Number of Titles', Count(*)
from titles
GROUP BY
    CASE
        WHEN price IS NULL THEN 'Unpriced'
        WHEN price < 10 THEN 'Bargain'
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/* °üº¬CÍ·Îļþ */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/* °üº¬SQLCAÍ·Îļþ */
EXEC SQL INCLUDE sqlca;
EXEC SQL INCLUDE sqlda;
int main()
{
    EXEC SQL BEGIN DECLARE SECTION;
    int  money;
    ......

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DCL—Êý¾Ý¿ØÖÆÓïÑÔ(GRANT£¬REVOKE£¬COMMIT£¬ROLLBACK)
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SQL ËÙ²éÊÖ²á

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/*******************************************/
SELECT
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SELECT column_name(s) from table_name
--Ö÷Òª×Ö¾ä¿ÉժҪΪ:
SELECT select_list [INTO new_table]
from table_source
[WHERE search_condition]
[GROUP BY group_by_expression]
[HAVING s ......

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