统计MySQL新列中相同的字符串？

使用COUNT()进行统计。首先创建一个表−

mysql> create table DemoTable
   (
   StudentFirstName varchar(20)
   );
Query OK, 0 rows affected (0.53 sec)

使用insert命令向表中插入记录−

mysql> insert into DemoTable values('Larry');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('John');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('Larry');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values('David');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values('Bob');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable values('Larry');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('David');
Query OK, 1 row affected (0.24 sec)
mysql> insert into DemoTable values('Larry');
Query OK, 1 row affected (0.14 sec)

使用select语句显示表中的所有记录−

mysql> select * from DemoTable;

输出如下−

+------------------+
| StudentFirstName |
+------------------+
| Larry            |
| John             |
| Larry            |
| David            |
| Bob              |
| Larry            |
| David            |
| Larry            |
+------------------+
8 rows in set (0.00 sec)

下面是在MySQL中计算相同字符串的查询−

mysql> select StudentFirstName,concat(count(StudentFirstName),' times') from DemoTable
group by StudentFirstName;

输出如下−

+------------------+------------------------------------------+
| StudentFirstName | concat(count(StudentFirstName),' times') |
+------------------+------------------------------------------+
| Larry            | 4 times                                  |
| John             | 1 times                                  |
| David            | 2 times                                  |
| Bob              | 1 times                                  |
+------------------+------------------------------------------+
4 rows in set (0.00 sec)

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