练习一
SQL 语句 :
select class_id,avg(score) from students group by class_id;
输出结果:
+----------+------------+ | class_id | avg(score) | +----------+------------+ | 1 | 86.5000 | | 2 | 73.6667 | | 3 | 88.3333 | +----------+------------+
练习二
SQL 语句:
select class_id,gender,avg(score) from students group by class_id,gender;
+----------+--------+------------+ | class_id | gender | avg(score) | +----------+--------+------------+ | 1 | F | 84.0000 | | 1 | M | 89.0000 | | 2 | F | 81.0000 | | 2 | M | 70.0000 | | 3 | F | 88.0000 | | 3 | M | 89.0000 | +----------+--------+------------+
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叮嘱111
练习一
SQL 语句 :
输出结果:
练习二
SQL 语句:
输出结果: