Which two statements are true regarding the USING and ON clauses in table joins?

A) The ON clause can be used to join tables on columns that have different names but compatible data types.

B) A maximum of one pair of columns can be joined between two tables using the ON clause.

C) Both USING and ON clauses can be used for equijoins and nonequijoins.

D) The WHERE clause can be used to apply additional conditions in SELECT statements containing the ON or the USING clause.

Answer：AD

(解析：D 答案正確，不管是 ON，還是 USING 子句，都要以在後面再添加 where 子句進行補充篩選;B 答案錯誤，ON 子句可以連接多個列;

using 不能用於不等連接

using 連接的字段可以 data type 不等，但是名字要相等

using 跟 natural join 是相互排斥的

using 的字段是不能夠再起別名

on 連接的字段 data type 要一致，名字可以不一樣

where 條件和 on 條件是分開處理的

)

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