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PostgreSQL determines whether it is empty coalesce

2022-07-22 17:29:00 【Apple elm maple】

PostgreSQL Determine whether it is null coalesce

SELECT goods_type_id, COALESCE(count(goods_type_id), 0) as count FROM goods_info GROUP BY goods_type_id

coalesce(expr1,expr2,expr3…)

Until we find a non null Value returns , The expression on the right does not participate in the operation ; If all are null, return null.

COALESCE Function to judge the non empty field , And specify the default value in the second parameter .

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