Question

What I want to do is compare two tables, and perform an update in tableb where column doesn’t match the same column.

I know in SQL this is

update tableb
   set myInt = 1
 where tableA.Column <> tableb.column

How is this done is MySQL?

Basically all I want to do is where tableA doesn’t have the same value in tableB update tableB.

Answer 1

Use:

UPDATE tableB 
   SET tableB.MyInt = 1 
 WHERE NOT EXISTS (SELECT NULL 
                     FROM tablea a
                    WHERE a.column = TableB.Column)

…which can also be written as:

   UPDATE TABLE_B
LEFT JOIN TABLE_A ON TABLE_A.COLUMN = TABLE_B.COLUMN
      SET TABLE_B.myint = 1
    WHERE TABLE_A.COLUMN IS NULL