SQL Server + Dynamic Query ‘Invalid Column Name’

sql

I am trying to execute the following dynamic query but I got an error: Invalid column name 'cat'

 DECLARE @SQLDelQuery AS NVARCHAR(1200)   
 DECLARE @MemberNames varchar(50)

 SET @MemberNames = 'cat'

      SET @SQLDelQuery = 'SELECT [Email] FROM [aspnet_Membership] am
      INNER JOIN [aspnet_Users] u
      ON (am.UserId = u.UserId)
      INNER JOIN [Member] m
      ON (am.UserId = m.UserId)
      WHERE u.UserName IN (' + @MemberNames + ')

  EXECUTE(@SQLDelQuery)

If I change it to the normal query I am fine:

SELECT [Email] FROM [aspnet_Membership] am
  INNER JOIN [aspnet_Users] u
  ON (am.UserId = u.UserId)
  INNER JOIN [Member] m
  ON (am.UserId = m.UserId)
  WHERE u.UserName IN ('cat')

Anyone can point out my error? Thanks.

Best Answer

Since cat is a varchar you need to include single quotes around it and you need to place the closing parentheses for the IN clause inside of the sql string.

The new code will be:

DECLARE @SQLDelQuery AS NVARCHAR(1200)   
 DECLARE @MemberNames varchar(50)

 SET @MemberNames = 'cat'

      SET @SQLDelQuery = 'SELECT [Email] FROM [aspnet_Membership] am
      INNER JOIN [aspnet_Users] u
      ON (am.UserId = u.UserId)
      INNER JOIN [Member] m
      ON (am.UserId = m.UserId)
      WHERE u.UserName IN (''' + @MemberNames + ''')'

  EXECUTE(@SQLDelQuery)

See a SQL Fiddle Demo with the query string printed. This generates a query string like this:

SELECT [Email] 
FROM [aspnet_Membership] am 
INNER JOIN [aspnet_Users] u 
  ON (am.UserId = u.UserId) 
INNER JOIN [Member] m 
  ON (am.UserId = m.UserId) 
WHERE u.UserName IN ('cat') -- cat surrounded in single quotes
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