MySQL Join Where Not Exists

Question

I have a MySQL query that joins two tables

• Voters
• Households

They join on voters.household_id and household.id

Answer 1

There are three possible ways to do that.

1. Option

   SELECT  lt.* FROM    table_left lt
   LEFT JOIN
       table_right rt
   ON      rt.value = lt.value
   WHERE   rt.value IS NULL
   

2. Option

   SELECT  lt.* FROM    table_left lt
   WHERE   lt.value NOT IN
   (
   SELECT  value
   FROM    table_right rt
   )
   

3. Option

   SELECT  lt.* FROM    table_left lt
   WHERE   NOT EXISTS
   (
   SELECT  NULL
   FROM    table_right rt
   WHERE   rt.value = lt.value
   )