'How to join three table

I'm having three tables, two of which are same in structure

table1 like this

-----------------------------------------------
id       title     description       image
-----------------------------------------------
1         title1   desc1             image1.png
2         title2    desc2            image2.jpg
------------------------------------------------

table2 like this

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id       title     description       image
-----------------------------------------------
1         ttl1   des1             img1.png
2         ttl2    des2            img2.jpg
------------------------------------------------

table 3 like this

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id       table1_id    table2_id     
-----------------------------------------------
1         0             1             
2         1             0    
------------------------------------------------

I want to join table3 to one of the other tables where id is not zero.

mysql


Solution 1:[1]

select * from table3  t3 
join table1 t1 on t1.id = t3.table2_id     
join table2 t2 on t2.id = t3.table1_id    
Where t3.table2_id <> 0 or  t3.table1_id    <> 0

Use direct join with Where

Solution 2:[2]

(select * from table3 as t3 join table1 as t1 on t1.id = t3.id and t3.table1_id != 0)
UNION
(select * from table3 as t3 join table2 as t2 on t2.id = t3.id and t3.table2_id != 0)

Sources

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Source: Stack Overflow

Solution Source
Solution 1 backtrack
Solution 2

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