Question

I am joining 2 tables -tbl1 and tbl2. Left join give all data from tbl1 which is in tbl2 or only on tbl1. Right join gives data from tbl2 which is don’t exists in tbl1.

I want to combine both results.

What is the best way to do this so that I get all data from tbl1 and tbl2?

Answer 1

The only you can do that is by using UNION. MySQL doesn’t support FULL JOINjust like in MSSQL.

SELECT * 
FROM tbl1 t1 
       LEFT JOIN tbl2 t2
          ON t1.col = t2.col
UNION 
SELECT * 
FROM tbl1 t1 
       RIGHT JOIN tbl2 t2 
          ON t1.col>= t2.<col

SEE HERE: Simulating FULL JOIN in MYSQL

By the way, UNION has optional keyword ALL,when the ALL is omitted, UNION automatically selects DISTINCT rows from the resultset.

EXAMLE:

SELECT *
FROM   tableA
UNION ALL
SELECT *
FROM   tableA

this can result duplicates rows

ColA    ColB
==================
1       John
2       Jade
2       Jade
3       Hello

BUT if you omit the word ALL

SELECT *
FROM   tableA
UNION
SELECT *
FROM   tableA

this can result distinct rows only

ColA    ColB
==================
1       John
2       Jade
3       Hello