I have two different tables : Table_a and Table_b, both have same columns PartNo and Material_Desc. I want the Material_Desc in Table_b to update the Material_Desc in Table_a when PartNo are equals. This is my query

MERGE INTO Table_b 
USING ( SELECT t1.rowid AS rid
               , t2.Material_Desc
        FROM Table_b t1 
           JOIN Table_a t2 
           ON Table_b.PartNo = Table_a.PartNo ) 
ON rowid = rid 
WHEN MATCHED THEN 
    UPDATE 
    SET Table_a.Material_Desc = Table_b.Material_Desc;

I know Oracle doesn't support joins for update statement so I tried the above query. Still it gives me ORACLE ORA-00969: missing ON keyword error

Edit
Report