To use a variable in a WHERE clause, you can concatenate the multicharacter wildcard operator % or the single character wildcard _ onto the variable to perform a fuzzy match.
WHERE u.UserName LIKE '%' + @myVariable + '%';Here’s an example of it in use:
-- First let's define a variable with a default value
DECLARE @myVariable VARCHAR(64) = 'Karen'
-- Then we concatenate the % wildcard onto the variable
SELECT
u.Id,
u.FirstName,
c.Content,
c.SubmittedAt
FROM [dbo].[sqlstr_Users] u
INNER JOIN [dbo].[sqlstr_Complaints] c ON u.Id = c.UserId
WHERE u.UserName LIKE '%' + @myVariable + '%';