Question

I have query that LEFT joins information from two tables. With code with following joins

LEFT JOIN A on source = news_id 
LEFT JOIN B on source = other_news_id

How can join or display data from the two columns so it produces one column information.

ID  source    Left Join on ID a   Left Join on ID b   
a    1            info1             <null>
a    2            info2             <null>
b    3            <null>            info3
b    4            <null>            info4

Something along the lines of

ID  source   info
a    1       info1             
a    2       info2
b    3       info3             
b    4       info4

How can I bring all left joins into one column?

Answer 1

You can use COALESCE() if there will always only be one value. It returns the first non-null argument.

SELECT ID, source, COALESCE(infoa, infob) AS info FROM ...