MySQL case-insensitive DISTINCT?

If you want case-insensitive distinct, you need to use UPPER() or LOWER().

Case 1: Using UPPER().

The syntax is as follows:

SELECT DISTINCT UPPER(yourColumnName) FROM yourTableName;

Case 2: Using LOWER().

The syntax is as follows:

SELECT DISTINCT LOWER(yourColumnName) FROM yourTableName;

To understand the above syntax, let us create a table. The query to create a table is as follows:

mysql> create table CaseInsensitiveDistinctDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT,
   -> UserEmailId varchar(30),
   -> UserPassword varchar(10),
   -> PRIMARY KEY(Id)
   -> );
Query OK, 0 rows affected (0.64 sec)

Now you can insert some records in the table using insert command. The query is as follows:

mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','john123');
Query OK, 1 row affected (0.15 sec)
mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','654321');
Query OK, 1 row affected (0.43 sec)
mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','999999');
Query OK, 1 row affected (0.14 sec)
mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','334556');
Query OK, 1 row affected (0.16 sec)
mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','1010101');
Query OK, 1 row affected (0.13 sec)
mysql> insert into CaseInsensitiveDistinctDemo(UserEmailId,UserPassword) values('[email protected]','12345678');
Query OK, 1 row affected (0.20 sec)

Display all records from the table using select statement. The query is as follows:

mysql> select *from CaseInsensitiveDistinctDemo;

The following is the output:

+----+-----------------+--------------+
| Id | UserEmailId     | UserPassword |
+----+-----------------+--------------+
|  1 | [email protected]  | john123      |
|  2 | [email protected]  | 654321       |
|  3 | [email protected]  | 999999       |
|  4 | [email protected]  | 334556       |
|  5 | [email protected] | 1010101      |
|  6 | [email protected] | 12345678     |
+----+-----------------+--------------+
6 rows in set (0.00 sec)

Here is the query to select case-insensitive distinct.

Case 1: Using UPPER(). The query is as follows:

mysql> select distinct upper(UserEmailId) from CaseInsensitiveDistinctDemo;

The following is the output:

+--------------------+
| upper(UserEmailId) |
+--------------------+
| [email protected]     |
| [email protected]     |
| [email protected]    |
| [email protected]    |
+--------------------+
4 rows in set (0.06 sec)

Case 2: Using LOWER(). The query is as follows:

mysql> select distinct lower(UserEmailId) from CaseInsensitiveDistinctDemo;

The following is the output:

+--------------------+
| lower(UserEmailId) |
+--------------------+
| [email protected]     |
| [email protected]     |
| [email protected]    |
| [email protected]    |
+--------------------+
4 rows in set (0.00 sec)