Note: To detect a cycle, only the results returned by the iterative SELECT statement are checked.

注意：要检测循环，在检测循环时，系统只会检查迭代select语句返回的结果。

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The result of the current iterative select statement is merged with the result of the initial select statement and all results returned by the previous iterations using a UNION ALL clause.

使用UNIONALL子句，可将当前的迭代SELECT语句的结果与初始 SELECT 语句的结果以及之前的迭代返回的所有结果合并在一起。

youdao

The result of the current iterative select statement is merged with the result of the initial select statement and all results returned by the previous iterations using a UNION ALL clause.

使用UNIONALL子句，可将当前的迭代SELECT语句的结果与初始 SELECT 语句的结果以及之前的迭代返回的所有结果合并在一起。

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