Get only the file extension from a column with file names as strings in MySQL?

For this, use the substring_index() function.

The syntax is as follows

select substring_index(yourColumnName, '. ', -1) AS anyAliasNamefrom yourTableName;

Let us first create a table. The query to create a table is as follows

mysql> create table AllFiles
   - > (
   - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   - > UserName varchar(10),
   - > FileName varchar(100)
   - > );
Query OK, 0 rows affected (0.65 sec)

Insert some records in the table using insert command.

The query is as follows

mysql> insert into AllFiles(UserName,FileName) values('Larry','AddTwoNumber.java');
Query OK, 1 row affected (0.18 sec)
mysql> insert into AllFiles(UserName,FileName) values('Mike','AddTwoNumber.python');
Query OK, 1 row affected (0.15 sec)
mysql> insert into AllFiles(UserName,FileName) values('Sam','MatrixMultiplication.c');
Query OK, 1 row affected (0.16 sec)
mysql> insert into AllFiles(UserName,FileName) values('Carol','vector.cpp');
Query OK, 1 row affected (0.15 sec)

Display all records from the table using select statement.

The query is as follows

mysql> select *from AllFiles;

The following is the output

+----+----------+------------------------+
| Id | UserName | FileName               |
+----+----------+------------------------+
|  1 | Larry    | AddTwoNumber.java      |
|  2 | Mike     | AddTwoNumber.python    |
|  3 | Sam      | MatrixMultiplication.c |
|  4 | Carol    | vector.cpp             |
+----+----------+------------------------+
4 rows in set (0.00 sec)

Here is the query to get only the file extension in MySQL

mysql> select substring_index(FileName,'.',-1) AS ALLFILENAMEEXTENSIONS from AllFiles;

The following is the output

+-----------------------+
| ALLFILENAMEEXTENSIONS |
+-----------------------+
| java                  |
| python                |
| c                     |
| cpp                   |
+-----------------------+
4 rows in set (0.00 sec)