Consulta MySQL para obter a contagem de todos os elementos no campo?

Para isso, use o método COUNT(). Vamos primeiro criar uma tabela:

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

Insira alguns registros na tabela usando o comando insert:

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)

Exiba todos os registros da tabela usando a instrução select:

mysql> select *from DemoTable;

Saída

Isso produzirá a seguinte saída:

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

A seguir está a consulta para obter a contagem de todos os elementos no campo:

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

Saída

Isso produzirá a seguinte saída:

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