Multi-Table query (Chapter Summary), Table query Chapter Summary

Multi-Table query (Chapter Summary), Table query Chapter Summary
1. Multi-Table query refers to a query operation that retrieves data from multiple tables at the same time.


2. During Multi-table queries, because the database retrieval mechanism produces the flute product, the flute product is the product of multiple data tables.


3. Two data table connection methods are available: internal connection and external connection.


4. You can use "(+)" in Oracle to control the left outer connection or right outer connection.


5. Self-join means that the table associates itself with its own operations.


6. You can use the SQL: 1999 syntax to perform multi-table queries.


7. Multiple queries can be connected using the set operation.
How to fill in the content and summary of the taxpayer's self-check table

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