Update row with select on same table

Question

I\'m trying to update row with same table query. Context:

ID        |  LANG       |  TEXT
----------------------------------
1         |  EN         |  Hello         


        

Answer 1

Update Test T1  INNER JOIN (SELECT T2.ID AS "id",MAX(T2.TEXTV) AS "MTEXT" FROM TEST T2
                             WHERE T2.LANG = 'EN'
                             AND T2.TEXTV IS NOT NULL   
                             GROUP BY T2.ID ) AS DER          
            ON T1.ID = DER.id

SET T1.TEXTV = DER.MTEXT
WHERE T1.TEXTV IS NULL ;   ------MySQL Query