v.20.7Improvement

Allow Standardized JOIN Syntax: Use LEFT SEMI JOIN Instead of SEMI LEFT JOIN

Official CH changelog text
Allow to set JOIN kind and type in more standad way: LEFT SEMI JOIN instead of SEMI LEFT JOIN. For now both are correct. #12520 (Artem Zuikov).
ClickHouse now supports specifying the JOIN kind and type in a more standard SQL syntax, such as using LEFT SEMI JOIN instead of the previously accepted SEMI LEFT JOIN. Both forms are currently supported.

Why it matters

This feature improves SQL syntax consistency by aligning with common SQL standards for JOIN clause ordering, making queries easier to read and write for users familiar with standard SQL conventions.

How to use it

Users can write JOIN clauses with the JOIN kind and type in the standard order, for example:

SELECT * FROM table1 LEFT SEMI JOIN table2 ON table1.id = table2.id


Both this new standard syntax and the former alternative are valid.

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