sql常用判斷語句

1:case when then else end

示例一

SELECT 學號, 姓名,
 等級=
    CASE
    WHEN 總學分 IS NULL THEN ‘尚未選課’
       WHEN 總學分 < 50 THEN ‘不及格’
        WHEN 總學分 >=50 and 總學分<=52 THEN ‘合格’
        ELSE ‘優秀’
    END  FROM  XS    WHERE 專業名=’計算機’

示例二

update employee
set e_wage =
 case
  when job_level = ’1’ then e_wage*1.08
  when job_level = ’2’ then e_wage*1.07
  when job_level = ’3’ then e_wage*1.06
  else e_wage*1.05
 end

示例三

select a, (case a when 1 then '中' else '國' end) AS B  from table1

 

2:isnull()

isnull(sum(incount),0)

 

3:存儲過程中執行存儲過程

 

  a:直接執行存儲過程

　　Exec [sp_OrderGetSendFee] @Cart_ID, 0, @User_ID, @tTotalPrice, @tSendFee, @tSendFee OutPut

  b:執行sql字符串

Set @Str = 'Select @All = Count(*) From ('+ @SQL + ') t'
 Exec sp_ExecuteSQL @Str, N'@All Int OutPut', @TotalRecord OutPut

 

4：執行拼湊sql 語句

 Exec sp_ExecuteSQL @Str