Query database without duplicate

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i have two database tables t1 and t2 and i want to insert all data from a third table t3 to t1 without duplicate data already in both t1 and t2? Please help

What I have tried:

Cherch for ideal solution for this problem

Posted 28-Feb-17 22:14pm

mamanes

Updated 28-Feb-17 23:53pm

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Graeme_Grant 1-Mar-17 4:33am

What have you tried?

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Peter Leow · Answer 1 · 2017-02-28T23:53:00

Assuming all the 3 tables have identical fields, say field1 and field2, except the primary keys if any,

INSERT INTO table1 (
SELECT * FROM table3 t3 WHERE NOT EXISTS (

(SELECT * FROM table1 t1 WHERE t1.field1=t3.field1 AND t1.field2=t3.field2) 
OR
(SELECT * FROM table2 t2 WHERE t2.field1=t3.field1 AND t2.field2=t3.field2)

))