declare @t table (col varchar(50))
insert @t select 'aa,bb,cc'
union all select 'AA,BB'
union all select 'AAA'
--create table tab (col varchar(50))
declare @i int,@s varchar(100)
select @s = ''
select col into tab from @t
while @@rowcount > 0
begin
select @i=@i+1
,@s = 'alter table tab add col'+cast(@i as varchar)+'varchar(10)'
print @s
exec(@s)
set @s = 'update tab set col'+cast(@i as varchar)+'=left(col,charindex('','',col+'','')-1),col = stuff(col,1,charindex('','',col+'',''),'''') where col>'''''
exec(@s)
end
select * from tab
要实现成这样的表,可是whlie循环怎么没执行呀
col1 col2 col3
aa bb cc
AA BB
AAA
insert @t select 'aa,bb,cc'
union all select 'AA,BB'
union all select 'AAA'
--create table tab (col varchar(50))
declare @i int,@s varchar(100)
select @s = ''
select col into tab from @t
while @@rowcount > 0
begin
select @i=@i+1
,@s = 'alter table tab add col'+cast(@i as varchar)+'varchar(10)'
print @s
exec(@s)
set @s = 'update tab set col'+cast(@i as varchar)+'=left(col,charindex('','',col+'','')-1),col = stuff(col,1,charindex('','',col+'',''),'''') where col>'''''
exec(@s)
end
select * from tab
要实现成这样的表,可是whlie循环怎么没执行呀
col1 col2 col3
aa bb cc
AA BB
AAA
1 :普通SQL语句可以用Exec执行 eg: Select * from tableName
Exec('select * from tableName')
Exec sp_executesql N'select * from tableName' -- 请注意字符串前一定要加N 2:字段名,表名,数据库名之类作为变量时,必须用动态SQL eg:
declare @fname varchar(20)
set @fname = 'FiledName'
Select @fname from tableName -- 错误,不会提示错误,但结果为固定值FiledName,并非所要。
Exec('select ' + @fname + ' from tableName') -- 请注意 加号前后的 单引号的边上加空格 当然将字符串改成变量的形式也可
declare @fname varchar(20)
set @fname = 'FiledName' --设置字段名 declare @s varchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句会报错 declare @s Nvarchar(1000) -- 注意此处改为nvarchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确 3. 输出参数
declare @num int,
@sqls nvarchar(4000)
set @sqls='select count(*) from tableName'
exec(@sqls)
--如何将exec执行结果放入变量中? declare @num int,
@sqls nvarchar(4000)
set @sqls='select @a=count(*) from tableName '
exec sp_executesql @sqls,N'@a int output',@num output
select @num
insert @t select 'aa,bb,cc '
union all select 'AA,BB '
union all select 'AAA ' --create table tab (col varchar(50)) select * into tab from @t
declare @i int,@s varchar(1000)
select @s = '' ,@i=0while exists(select 1 from tab where charindex(',',col+',')>1)
begin
select @i=@i+1,@s ='alter table tab add [col'+cast(@i as varchar)+ '] varchar(10) '
exec (@s)
--print @s
set @s='update tab set [col'+cast(@i as varchar)+ ']=left(col,charindex( '','',col+ '','')-1),col = stuff(col,1,charindex( '','',col+ '',''),'''') where col > '''''
exec(@s)
--print @s
end
select * from tab go
--drop table tabcol col1 col2 col3
-------------------------------------------------- ---------- ---------- ----------
aa bb cc
AA BB NULL
AAA NULL NULL(所影响的行数为 3 行)