SQL Substring in WHERE clause I'm trying to build a SQL query that will show me all the products that have products.description IS NULL but also have a corresponding description in the descriptions table.   So code is always a substring of info.

The products.code is a substring of descriptions.info, so I'm not sure how to pull this.

products

id |  code   |  description
--------------------------
1    12345-1      NULL


descriptions

id |  info
---------------------------
1     12345-1_Hammer
You need t o compare product.info with descriptions.info. If the needed condition is for one to be a substring of the other, it can be done with LIKE.

Since there may be more than one descriptions matching (having as substring) a product code, we should use an EXISTS subquery:

SELECT p.id, p.code
FROM products AS p
WHERE p.description IS NULL
  AND EXISTS
      ( SELECT *
        FROM descriptions AS d 
        WHERE d.info LIKE '%' + p.code + '%'
      ) ;