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Comment: comma token in FROM clause (HIVE-5558), link to Select doc

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Only equality joins, outer joins, and left semi joins are supported in Hive. Hive does not support join conditions that are not equality conditions as it is very difficult to express such conditions as a map/reduce job. Also, more than two tables can be joined in Hive.

See Select Syntax for the context of this join syntax.

Info
titleVersion

Implicit join notation is supported starting with Hive 0.13.0 (see HIVE-5558). This allows the FROM clause to join a comma-separated list of tables, omitting the JOIN keyword. For example:

SELECT *
FROM table1 t1, table2 t2, table3 t3
WHERE t1.id = t2.id AND t2.id = t3.id AND t1.zipcode = '02535';

Examples

Some salient points to consider when writing join queries are as follows:

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