sql replace substring with value from associated table

Update TableA
set ColumnA1 = (select a.ColumnA from
(
"SELECT" REPLACE("t.ColumnA1, t.ColumnA2", (select "ColumnB1 from TableA where ColumnB2= t.ColumnA2))
FROM TableA t
) a
where TableA.ColumnA2 = a.ColumnA2)
GO