sql - MySQL - Update siblings with same key -

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couldn't find solution yet... although newbie question, haven't been able overcome... hope can give hand.

i have mysql table has:

blockquote

     col1  col2 row1     null row2     a1 row3     null row4 b     null row5 b     b1 etc  > blockquote

how construct sql update update col2, values on col2 replace null, ie, c2r1 , c2r3 gets a1, , c2r4 gets b1 ?

you can calculate required values follows:

create temporary table yourtemptable select yourtable.col1, t1.col2 yourtable join (     select col1, max(col2) col2     yourtable     group col1 ) t1 on yourtable.col1 = t1.col1

you can either drop/truncate original table , recreate using these values, or if can't drop table can instead perform multi-table update.


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