Comments - User-Defined Variables
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thanks you very much! i have one more question.
SELECT A.*
,IF(@PREV_JOB=JOB ,@ROWNUMBER:=@ROWNUMBER+1 ,@ROWNUMBER:=1+LEAST(0,@PREV_JOB:=JOB)) AS ROWNUMBER
FROM (SELECT EMP.* --here is inline view
FROM EMP
,(SELECT @ROWNUMBER:=0, @PREV_JOB:='') X
ORDER BY JOB, SAL) A;
As far as I know, mariaDB's inliview ordering is not working.
so i input the sentence ",(SELECT @ROWNUMBER:=0, @PREV_JOB:='') X".
then inline view was ordered, and result was fine.
with out this sentence, sort is not occur in execution plan.
is this ordering is legal? guaranteed? or not guaranteed?
i'm sorry for my poor English. thanks you.