sql optimization with anti join

sql,query-optimization,anti-join

If you want to join data, use something like this (SQL server example): DECLARE @category TABLE (id INT IDENTITY(1,1), name VARCHAR(30), parent INT) -- parent is foreign key to category id :) DECLARE @company TABLE (id INT IDENTITY(1,1), category_1 INT, category_2 INT, category_3 INT) --category_* is foreign key to category->id...

MySQL Anti Join

mysql,anti-join

SELECT Id, Name FROM Course WHERE Id NOT IN ( SELECT IdCourse FROM Teacher WHERE IdUser = 10 AND IdSchool = 4 ); ...