Question

如何使下面的语法更有效，因为我必须为一条记录更新超过20个字段？

 UPDATE TRANS SET A = @XA WHERE UNIQX = @XUNIQX AND STS_TRANS = 0 and A <> @XA
 UPDATE TRANS SET B = @XB WHERE UNIQX = @XUNIQX AND STS_TRANS = 0 and B <> @XB 
 UPDATE TRANS SET C = @XC WHERE UNIQX = @XUNIQX AND STS_TRANS = 0 and C <> @XC 
 UPDATE TRANS SET D = @XD WHERE UNIQX = @XUNIQX AND STS_TRANS = 0 and D <> @XD 
 UPDATE TRANS SET E = @XE WHERE UNIQX = @XUNIQX AND STS_TRANS = 0 and E <> @XE

Answer 1

你可以把它结合起来：

UPDATE TRANS 
SET A = @XA
   ,B = @XB
   ,C = @XC
   ,D = @XD
   ,E = @XE
WHERE UNIQX = @XUNIQX 
  AND STS_TRANS = 0;

即使A与@XA不同，也会有A - ＆gt; A（同一性）。

请注意，如果A列可以为空，A <> @XA可能会很棘手：what is “=null” and “ IS NULL”

Answer 2

使用这样的循环和动态sql：

    create table #temp (idx int identity, column_name varchar(max))
    insert #temp
    select column_name from INFORMATION_SCHEMA.columns
    where table_name='trans' --and filter columns you want here

    declare @XUNIQX varchar(max) --set value here
    declare @itrerator int = 1
    declare @columnname varchar(max)
    while @itrerator<=(select max(idx) from #temp)
begin
    select @columnname=column_name from #temp where idx=@iterator
    exec ('UPDATE TRANS SET '+@columnname+' = @X'+@columnname+' WHERE UNIQX ='+ @XUNIQX+' AND STS_TRANS = 0 and '+@columnname+' <> @X'+@columnname+'')
set @iterator=@iterator+1
    end

高效的SQL更新查询

2 个答案: