如何使用Code Igniter中的除代码进行选择

Question

this is what I want in SQL: select id from mytable except select id from another_table,

but with CI's database library to use EXCEPT function, how do I obtain it?

Answer 1

You can accomplish this using NOT EXISTS

SELECT
    MT.id
FROM
    mytable AS MT
WHERE NOT EXISTS (
    SELECT
        AT.id
    FROM another_table AS AT 
    WHERE AT.id = MT.id
)