同時有COUNT(DISTINCT)和GROUP BY的慢查詢sql優化實例

項目中碰到一個慢查詢，裏面既有COUNT(DISTINCT)，又有GROUP BY，查詢性能不好，26萬條數據查詢下來須要18秒，sql以下html SELECT a.channel_code AS channelCode, a.channel_name AS channelName, DATE_FORMAT(a.create_date, '%Y') AS orderDate, COUNT

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