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This article shows you how to use the USING keyword in Oracle database to simplify the connection, the content is concise and easy to understand, absolutely can make you shine, through the detailed introduction of this article I hope you can gain something.

1. The query must be equal-joined

2. Columns in an equal join must have the same name

Most of the joins performed are equal joins, and these restrictions can be satisfied if you always use the same name for the primary key.

Note that only the column name can be specified in the SELECT clause, and table names or aliases cannot be used. If you try to use a table alias before a column,

See an error like this:

Also note that column names can only be used in the USING clause alone. If you try to call USING(p.product_type_id) to USING(product_type_id) in the above example, you will see the following error:

SQL>SELECT p.name,pt.name,p.product_type_id

2 FROM products p INNER JOIN product_types pt

3 USING(p.product_type_id);

USING(p.product_type_id)

*

ERROR at line 3;

ORA-01748：only simple column names allowed here

Warning:

Do not use table names or aliases when referencing columns in USING clauses, otherwise an error will occur.

The above is how to use the USING keyword in Oracle database to simplify the connection. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserves, please pay attention to the industry information channel.

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