oracle多表查詢(文件)
【正文】 he ON Clause SELECT employee_id, city, department_name FROM employees e JOIN departments d ON = JOIN locations l ON = 。 全外連接 … SELECT , , , , FROM employees e JOIN departments d ON ( = ) AND = 149 。 左外連接 … SELECT , , FROM employees e RIGHT OUTER JOIN departments d ON ( = ) 。 Retrieving Records with Natural Joins Creating Joins with the USING Clause ? If several columns have the same names but the data types do not match, the NATURAL JOIN clause can be modified with the USING clause to specify the columns that should be used for an equijoin. ? Use the USING clause to match only one column when more than one column matches. ? Do not use a table name or alias in the referenced columns. ? The NATURAL JOIN and USING clauses are mutually exclusive. SELECT , , FROM employees e JOIN departments d USING (department_id) 。 || FROM employees worker, employees manager WHERE = 。 SELECT , FROM table1, table2 WHERE =
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