SQL：我想从第二个表中提取数据。 由于第二个表的列名与第一个表列的逗号分隔的值匹配

Question

I have a table1 with one column with values seperated by comma firstname,lastname . I have a table2 with two column names firstname and lastname , which match with table1's single column values( firstname,lastname ). My necessity is I want to extract data from table2 by using select statement SELECT firstname,lastname FROM table2 . I used variables to write query.

I transferred values of table1( firstname, lastname ) to @link variable and this operation completed successfully. But when i tried to add SELECT @link FROM table2 to the query i thought i would get data of firstname and lastname of table2, But result showing a seperate no column name and value in that column as firstname,lastname .

Tons of Thanks for any help!

declare @link nvarchar(max)
    select @link = (select [column]
    from [dbo].[table1])
    from [dbo].[table2]
    SELECT @link FROM table2 

Answer 1

You appear to be attempting "dynamic sql", ie you build a string that contains a select statment, then execute that string as a query. Conventionally you will find many example that use @sql for this, and the basic fom of this is as follows:

declare @sql nvarchar(max)

select @sql = N'select [column] from [dbo].[table1]'

EXEC sp_executesql @sql;

Note that the @sql contents has to be valid sql syntax. On this point your code contains 2 from clauses and that is NOT valid, plus it isn't clear what you intended, perhaps it was meant to be a join.

declare @sql nvarchar(max)

select @sql = N'select t.[column], j.[column2]
from [dbo].[table1] as t
inner join [dbo].[table2] as j on t.id = j.fk'

EXEC sp_executesql @sql;