Minus deviation value in Oracle

The main functions of the minus operation are: when two tables or two query results are performed,
Returns a record in the first table/query result that is not the same as the second table/query result.

For example: The first sheet Course_homework_record Reply_affix

Second sheet resources_mapping_new file_id

Returns: three non-repeating data.

Like what:

Conclusion: Minus returns always the data from the first table, which returns the difference set. Note: Minus has a de-redo effect.

Reprint Please specify: Zhang does not nap blog http://my.oschina.net/zhangbudun/blog/341554

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Minus deviation value in Oracle