v.20.6Improvement

Allowed Standardization of JOIN Syntax to LEFT SEMI JOIN

Official CH changelog text
Allowed to set JOIN kind and type in more standard way: LEFT SEMI JOIN instead of SEMI LEFT JOIN. For now both are correct. #12520 (Artem Zuikov).
Allowed setting 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 now supported.

Why it matters

To improve SQL syntax compatibility and clarity by aligning ClickHouse's JOIN clause syntax with common SQL standards. This enhancement reduces confusion and makes queries more intuitive for users familiar with standard SQL join syntax.

How to use it

Users can specify joins using the standard SQL format like LEFT SEMI JOIN in their queries. Existing syntax like SEMI LEFT JOIN remains valid, so no changes are required, but the preferred and clearer syntax is now supported.

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