如何将变量放到sql语句中

[sheepboy]

比如在：select name from syscolumns where id=object_id('表名')中
我用一个变量来表示'表名'，应该用什么类型，又怎样放到这句sql语句里面？

[wgsasd311]

declare @name varchar(4000)
declare curcol cursor for
select name from syscolumns where id=object_id('表名')
open curcol
fetch next from curcol into @name
exec('select '+@name+ ' from 表名')

[vivianfdlpw]

declare @tbName varchar(20)
set @tbName='syscolumns'
select name from syscolumns where id=object_id(@tbName)

[云中客]

declare @tbName varchar(20)
set @tbName='syscolumns'
select name from syscolumns where id=object_id(@tbName)

[sheepboy]

在c#中呢？

[vivianfdlpw]

string tbName="syscolumns"; //表名
StringBuilder sb=new StringBuilder ();
sb.Append (" declare @tbName varchar(20)");
sb.Append (" set @tbName='"+tbName+"'");
sb.Append (" select name from syscolumns where id=object_id(@tbName)");

SqlCommand cmd=new SqlCommand ();
cmd.CommandText =sb.ToString ();
cmd.Connection .Open ();
SqlDataReader dr=cmd.ExecuteReader();

[vivianfdlpw]

或者写一个存储过程：

create procedure p
@tbName varchar(20)
as
select name from syscolumns where id=object_id(@tbName)
go

然后C#中：
string tbName="syscolumns"; //表名
SqlCommand cmd=new SqlCommand ();
cmd.CommandText ="p";
cmd.CommandType =CommandType.StoredProcedure;
cmd.Parameters .Add (new SqlParameter ("@tbName",SqlDbType.VarChar,20));
cmd.Parameters [0].Value =tbName;
cmd.Connection .Open ();
SqlDataReader dr=cmd.ExecuteReader();