如何借助分组函数 COUNT(*) 和 GROUP BY 子句知道列中某个值的重复次数？

mysql> select count(*),name from student group by name; +----------+---------+ | count(*) | name | +----------+---------+ | 1 | Aarav | | 2 | Gaurav | | 1 | Harshit | +----------+---------+ 3 rows in set (0.00 sec)

上面查询的结果集显示了哪个值在列中重复了多少次。在上面的示例中，“Gaurav”在“name”列中重复两次。可以从下面的‘SELECT *’ 查询中验证同样的情况 -

mysql> Select * from Student;

+------+---------+---------+-----------+
| Id   | Name    | Address | Subject   |
+------+---------+---------+-----------+
| 1    | Gaurav  | Delhi   | Computers |
| 2    | Aarav   | Mumbai  | History   |
| 15   | Harshit | Delhi   | Commerce  |
| 20   | Gaurav  | Jaipur  | Computers |
+------+---------+---------+-----------+

4 rows in set (0.00 sec)

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