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Lu, Huayi 346ac31da9 DWS TG 8.1.3.200 VERSION 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Reviewed-by: Jiang, Beibei <beibei.jiang@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2023-08-28 09:20:17 +00:00

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OUTER JOIN

This section describes the migration syntax of Oracle OUTER JOIN. The migration syntax determines how the keywords/features are migrated.

An OUTER JOIN returns all rows that meet the join condition. If rows of a table cannot join any rows in the other table, the statement returns these rows. In Oracle:

  • Left outer join of tables A and B returns all rows from A and rows that satisfy the join condition by applying the outer join operator (+) to all columns of B in the WHERE conditions.
  • Right outer join of tables A and B returns all rows from B and rows that satisfy the join condition by applying the outer join operator (+) to all columns of A in the WHERE condition.

GaussDB(DWS) does not support the + operator. The function of this operator is enabled using LEFT OUTER JOIN and RIGHT OUTER JOIN keywords.

Figure 1 Input: OUTER JOIN
Figure 2 Output: OUTER JOIN
Parent topic: Oracle Syntax Migration