我们可以使用 count(*) 和 group by 子句来找出列中某个值的重复情况。以下是在“student”表的“name”列上使用 count(*) 和 group by 子句的示例来演示 -
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)
以上就是如何借助分组函数 count(*) 和 group by 子句知道列中某个值的重复次数？的详细内容。