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Select three random records with a fixed number of characters for each column value in MySQL
For this, you can use CHAR_LENGTH(). Use RAND() for random records. Let us first create a table −
mysql> create table DemoTable (Subject text); Query OK, 0 rows affected (0.61 sec)
Example
Insert some records in the table using insert command −
mysql> insert into DemoTable values('C');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values('MySQL');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('Java');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('MongoDB');
Query OK, 1 row affected (0.59 sec)
mysql> insert into DemoTable values('RubyOnRails');
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable values('C++');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('Python');
Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
Output
+-------------+ | Subject | +-------------+ | C | | MySQL | | Java | | MongoDB | | RubyOnRails | | C++ | | Python | +-------------+ 7 rows in set (0.00 sec)
Following is the query to select 3 random records with fixed number of characters for each −
mysql> select *from (select *from DemoTable WHERE CHAR_LENGTH(Subject) = 7 ORDER BY RAND() LIMIT 1 ) tbl UNION (select *from DemoTable WHERE CHAR_LENGTH(Subject) = 11 ORDER BY RAND() LIMIT 1 ) UNION (select *from DemoTable WHERE CHAR_LENGTH(Subject) = 5 ORDER BY RAND() LIMIT 1 );
Output
+-------------+ | Subject | +-------------+ | MongoDB | | RubyOnRails | | MySQL | +-------------+ 3 rows in set (0.04 sec
Updated on: 02-Jul-2020
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