如何在 MySQL 中获取列中每个不同值的数量?
mysqlmysqli database
让我们看一个例子来获取列中每个不同值的数量。首先，我们将创建一个表。
CREATE 命令用于创建表。
mysql> create table DistinctDemo1 - > ( - > id int, - > name varchar(100) - > ); Query OK, 0 rows affected (0.43 sec)
插入记录
mysql> insert into DistinctDemo1 values(1,'John'); Query OK, 1 row affected (0.34 sec) mysql> insert into DistinctDemo1 values(2,'John'); Query OK, 1 row affected (0.20 sec) mysql> insert into DistinctDemo1 values(3,'John'); Query OK, 1 row affected (0.09 sec) mysql> insert into DistinctDemo1 values(4,'Carol'); Query OK, 1 row affected (0.17 sec) mysql> insert into DistinctDemo1 values(5,'David'); Query OK, 1 row affected (0.12 sec)
显示所有记录
mysql> select *from DistinctDemo1;
以下是显示所有记录的输出。
+------+-------+ | id | name | +------+-------+ | 1 | John | | 2 | John | | 3 | John | | 4 | Carol | | 5 | David | +------+-------+ 5 rows in set (0.00 sec)
以下是获取计数的语法。
mysql> SELECT name,COUNT(1) as OccurenceValue FROM DistinctDemo1 GROUP BY name ORDER BY OccurenceValue;
这是输出。
+-------+----------------+ | name | OccurenceValue | +-------+----------------+ | Carol | 1 | | David | 1 | | John | 3 | +-------+----------------+ 3 rows in set (0.04 sec)
