Count how many rows have the same value in MySQL?
To count how many rows have the same value using the function COUNT(*) and GROUP BY. The syntax is as follows −
SELECT yourColumName1, count(*) as anyVariableName from yourTableName GROUP BY yourColumName1;
To understand the above syntax, let us first create a table. The query to create a table is as follows −
mysql> create table RowWithSameValue
−> (
−> StudentId int,
−> StudentName varchar(100),
−> StudentMarks int
−> );
Query OK, 0 rows affected (0.55 sec)
Insert some records with same value. Here, we have added same marks for more than one student for our example. The query to insert records is as follows −
mysql> insert into RowWithSameValue values(100,'Carol',89);
Query OK, 1 row affected (0.21 sec)
mysql> insert into RowWithSameValue values(101,'Sam',89);
Query OK, 1 row affected (0.15 sec)
mysql> insert into RowWithSameValue values(102,'John',99);
Query OK, 1 row affected (0.12 sec)
mysql> insert into RowWithSameValue values(103,'Johnson',89);
Query OK, 1 row affected (0.15 sec)
Now you can display all records which we inserted above. The query to display all records is as follows −
mysql> select *from RowWithSameValue;
The following is the output −
+-----------+-------------+--------------+
| StudentId | StudentName | StudentMarks |
+-----------+-------------+--------------+
| 100 | Carol | 89 |
| 101 | Sam | 89 |
| 102 | John | 99 |
| 103 | Johnson | 89 |
+-----------+-------------+--------------+
4 rows in set (0.00 sec)
Implement the syntax we discussed in the beginning to count rows that have the same value −
mysql> SELECT StudentMarks, count(*) as SameValue from RowWithSameValue GROUP BY StudentMarks;
The following is the output that displays count of multiple values −
+--------------+-----------+
| StudentMarks | SameValue |
+--------------+-----------+
| 89 | 3 |
| 99 | 1 |
+--------------+-----------+
2 rows in set (0.00 sec)
Published on 10-Jan-2019 12:25:14
