What is the most efficient way to select a specific number of random rows in MySQL?

Use RAND() method for random and to limit a number of records, use the LIMIT() method in MySQL.

Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Value int
   -> );
Query OK, 0 rows affected (0.54 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(100);
Query OK, 1 row affected (0.19 sec)

mysql> insert into DemoTable values(300);
Query OK, 1 row affected (0.16 sec)

mysql> insert into DemoTable values(600);
Query OK, 1 row affected (0.12 sec)

mysql> insert into DemoTable values(700);
Query OK, 1 row affected (0.14 sec)

mysql> insert into DemoTable values(1000);
Query OK, 1 row affected (0.15 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+-------+
| Value |
+-------+
|   100 |
|   300 |
|   600 |
|   700 |
|  1000 |
+-------+
5 rows in set (0.00 sec)

Following is the query to get a specific number of rows with random records −

mysql> select *from DemoTable order by rand() limit 4;

Output

+-------+
| Value |
+-------+
|  1000 |
|   600 |
|   100 |
|   700 |
+-------+
4 rows in set (0.00 sec)