query to obtain the missing content between two tables

开发者_JAVA技巧

I have two tables table A and Table B , i have used primary key of the table A as a Reference in table B , i need help to write a query to obtain the content that is present only in table A but missing in table b.

thanks in advance

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SELECT * FROM tbl_a
LEFT JOIN tbl_b ON tbl_b.a_id = tbl_a.id
WHERE tbl_b.id IS NULL