Specify that joined tables should include rows even when they do not match rows in the corresponding table.
指定即使某些行与相应表中的行不匹配,联接表也应包含这些行。
This row would not have appeared in the output from a standard JOIN, so the LEFTOUTER JOIN statement was used to include rows from the DEPT table that did not have any matching rows in the EMP table.
如果使用标准的JOIN,这行将不会出现在结果中,所以就使用LEFTOUTER JOIN语句来包含来自DEPT表中的但是不匹配EMP表任何行的记录。
Although this example doesn't explicitly demonstrate their use, you can also include the SQL functions discussed in Part 5 to gain more control over the selection of rows for deletion.
您还可以包括第5部分中讨论的sql函数以获得对删除行的选择的更多控制,但是本例中没有明确演示这些函数的使用。
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