How can I order in group but randomly with MySQL?
Let us first create a table −
mysql> create table DemoTable
(
Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
Value char(1)
);
Query OK, 0 rows affected (0.66 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable(Value) values('X');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable(Value) values('Y');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable(Value) values('X');
Query OK, 1 row affected (0.30 sec)
mysql> insert into DemoTable(Value) values('X');
Query OK, 1 row affected (0.07 sec)
mysql> insert into DemoTable(Value) values('Y');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(Value) values('Z');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(Value) values('Z');
Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+-------+
| Id | Value |
+----+-------+
| 1 | X |
| 2 | Y |
| 3 | X |
| 4 | X |
| 5 | Y |
| 6 | Z |
| 7 | Z |
+----+-------+
7 rows in set (0.00 sec)
Case 1 − Following is the query to group but randomly −
mysql> select DemoTable.*
from DemoTable join
(
select Value, rand() as `random_Value`
from DemoTable
group by Value
) tbl2
on DemoTable.Value = tbl2.Value
order by tbl2.`random_Value`;
This will produce the following output −
+----+-------+
| Id | Value |
+----+-------+
| 6 | Z |
| 7 | Z |
| 1 | X |
| 3 | X |
| 4 | X |
| 2 | Y |
| 5 | Y |
+----+-------+
7 rows in set (0.00 sec)
Case 2 − Let us run the above query again to display since we are showing random records −
mysql> select DemoTable.*
from DemoTable join
(
select Value, rand() as `random_Value`
from DemoTable
group by Value
) tbl2
on DemoTable.Value = tbl2.Value
order by tbl2.`random_Value`;
This will produce the following output −
+----+-------+
| Id | Value |
+----+-------+
| 2 | Y |
| 5 | Y |
| 6 | Z |
| 7 | Z |
| 1 | X |
| 3 | X |
| 4 | X |
+----+-------+
7 rows in set (0.00 sec)
Published on 20-May-2019 16:42:09
