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我需要计算不存在的外键,如图所示,并在列表名称中包含字母'a' .
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我只能计算值,但无法用字母'a'指定名称 .
我正在使用伯爵:
SELECT l.identifier AS id, l.name AS listName, COUNT(p.list_identifier)
AS regCount FROM list AS l LEFT JOIN person AS p ON l.identifier = p.list_identifier
WHERE p.list_identifier IS NULL GROUP BY l.name;
请帮帮我 .
1 回答
尝试使用left outer join&COUNT(DISTINCT ...)