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MySQL query to avoid displaying duplicates values?
For this, you can use GROUP BY and use COUNT to get only non-duplicate values. Following is the syntax −
select yourColumnName from yourTableName group by yourColumnName having count(*)=1;
Let us first create a table −
mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Subject varchar(100) -> ); Query OK, 0 rows affected (0.70 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable(Subject) values('MySQL');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable(Subject) values('Java');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(Subject) values('C');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(Subject) values('C++');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(Subject) values('Java');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable(Subject) values('C');
Query OK, 1 row affected (0.23 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
Output
+----+---------+ | Id | Subject | +----+---------+ | 1 | MySQL | | 2 | MongoDB | | 3 | Java | | 4 | MongoDB | | 5 | C | | 6 | C++ | | 7 | Java | | 8 | C | +----+---------+ 8 rows in set (0.00 sec)
Here is the query to avoid displaying duplicates −
mysql> select Subject from DemoTable group by Subject having count(*)=1;
Output
+---------+ | Subject | +---------+ | MySQL | | C++ | +---------+ 2 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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