使用 [GROUP BY ] [HAVING ] 進行分組查詢(示例結果如圖按順序)

新增分組字段

ALTER TABLE study_1 ADD study_group int(11);

為原有的數據分組

UPDATE study_1 set study_group=1 where id<3;

UPDATE study_1 set study_group=2 where id>=3 AND id<7;

UPDATE study_1 set study_group=3 where id>=7;

示例1.把各分組的姓名按分組查詢并組合起來。

SELECT GROUP_CONCAT(name) AS names,study_group FROM study_1 GROUP BY study_group;

示例2.把各分組的姓名按分組查詢并組合起來,并使用HAVING限制查詢分組人數在2人以上的數據。

SELECT GROUP_CONCAT(name) AS names,study_group,sex FROM study_1 GROUP BY study_group HAVING COUNT(name)>2;

示例3.把各分組的姓名按分組查詢并組合起來,WITH ROLLUP在最后一條顯示所有記錄。

SELECT GROUP_CONCAT(name) AS names,study_group FROM study_1 GROUP BY study_group WITH ROLLUP;

示例4.多字段分組

SELECT GROUP_CONCAT(name) AS names,study_group,sex FROM study_1 GROUP BY study_group,sex;

總結

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