将where子句作为存储过程参数传递时出错

Question

I have created following stored procedure in SQL Server,

create procedure sp_test
    @columns nvarchar(max),
    @tablename nvarchar(max),
    @whereClause nvarchar(max)
as
   DECLARE @sql AS NVARCHAR(MAX)
   SET @sql = 'SELECT ' + @columns + ' FROM ' + @tablename + @whereClause;

   EXEC sp_executesql @sql

I am trying to call it like this

exec sp_test 'title,name','person','where name = ''john'''

And I'm getting an error like this,

Msg 102, Level 15, State 1, Line 1
Incorrect syntax near '='.

Answer 1

You have an extra single quote, why not use double quote, like:

exec sp_test 'title,name','person'," where name = 'john'"

Add an extra space also here:

SET @sql = 'SELECT ' + @columns + ' FROM ' + @tablename+ ' ' + @whereClause;

Answer 2

Hint: It's because

SELECT title,name FROM personwhere name = 'john'

is not a valid SQL.

The reason should be obvious now and is left as an exercise to the reader...