Truy vấn MySQL đếm số lần xuất hiện mỗi giá trị trong cột

Sử dụng COUNT() kết hợp GROUP BY. Tạo bảng:

mysql> create table DemoTable -> ( -> ProductName varchar(100) -> ); Query OK, 0 rows affected (0.59 sec)

Chèn dữ liệu:

mysql> insert into DemoTable values('Product-1'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values('Product-2'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Product-3'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('Product-3'); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable values('Product-2'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Product-4'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Product-5'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Product-1'); Query OK, 1 row affected (0.11 sec)

Hiển thị dữ liệu:

mysql> select *from DemoTable;

Kết quả

+-------------+ | ProductName | +-------------+ | Product-1 | | Product-2 | | Product-3 | | Product-3 | | Product-2 | | Product-4 | | Product-5 | | Product-1 | +-------------+ 8 rows in set (0.00 sec)

Truy vấn đếm và nhóm:

mysql> select ProductName,count(ProductName) as TotalCount from DemoTable group by ProductName;

Kết quả

+-------------+------------+ | ProductName | TotalCount | +-------------+------------+ | Product-1   | 2          | | Product-2   | 2        | | Product-3 | 2 | | Product-4 | 1 | | Product-5 | 1 | +-------------+------------+ 5 rows in set (0.05 sec)