One example : sql can join tables or nest queries 例如: sql可以连接表或嵌套查询。
Explains how to create subqueries , or nested queries 解释如何创建子查询或嵌套查询。
You can always convert a nested query into an equivalent join 您始终可以将嵌套查询转换成等价的连接。
Otherwise , the nested query must be processed for each result of the outer query to ensure elimination of duplicates 否则,为确保消除重复值,必须为外部查询的每个结果都处理嵌套查询。
In general , sql 2005 notification supports select queries as well as stored procedures , and supports multiple and nested queries , but does not support aggregate operations such as 总之, sql 2005通知支持select查询和存储过程,支持多个查询和嵌套查询,但不支持聚合操作(例如