How to make joins in cases in mysql

132

December 22, 2018, at 04:40 AM

I am trying to construct the following query, I know the syntax is incorrect but could anyone suggest any ideas?/solution?

Thanks 
SELECT * FROM table 
LEFT JOIN x ON x.id = table.id 
CASE table.nid 
WHEN 1 THEN (LEFT JOIN tablea ON tablea.id = table.nid) 
WHEN 2 THEN (LEFT JOIN tableb ON tableb.id = table.nid) 
WHEN 3 THEN (LEFT JOIN tablec ON tablec.id = table.nid) 
END 
WHERE talbe.id = "hello";

Answer 1

i'm not sure this is the most efficient/pretty ways but you can try this :

SELECT CASE table.nid WHEN 1 THEN tablea.id WHEN 2 THEN tableb.id WHEN 3 THEN tablec.id end
FROM table
LEFT JOIN x ON x.id = table.id 
LEFT JOIN tablea ON tablea.id = table.nid
LEFT JOIN tableb ON tableb.id = table.nid
LEFT JOIN tablec ON tablec.id = table.nid 
WHERE talbe.id = "hello";

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