あいまいな列名：SqliteのDELETE

Question

ここは私のクエリです。

DELETE 
FROM CategoryProduct_MM 
WHERE PrdID IN 
(SELECT PrdID FROM CategoryProduct_MM t1 
INNER JOIN db2.CategoryProduct_MM t2 
ON (t1.PrdID = t2.PrdID AND t1.CategoryID=t2.CategoryID)); 

なぜこのエラーが発生しますか？

ambiguous column name: PrdID: DELETE 

Answer 1

DELETE 
FROM CategoryProduct_MM 
WHERE PrdID IN 
(SELECT t1.PrdID FROM CategoryProduct_MM t1 
INNER JOIN db2.CategoryProduct_MM t2 
ON (t1.PrdID = t2.PrdID AND t1.CategoryID=t2.CategoryID));