Why is “LIMIT 0” even allowed in MySQL SELECT statements?
As you know if you use LIMIT 0 in MySQL SELECT statement, it returns an empty set.
The LIMIT can be used when you want a specified number of rows from a result rather than the entire rows. If you use any MySQL API, then the job of LIMIT is to acquire the type of result columns.
LIMIT 0 can be used to check the validity of a query. For more details use the following link −
https://dev.mysql.com/doc/refman/8.0/en/limit-optimization.html
Here is the demo of LIMIT 0. The query to create a table is as follows −
mysql> create table Limit0Demo
-> (
-> Id int NOT NULL AUTO_INCREMENT,
-> Name varchar(20),
-> PRIMARY KEY(Id)
-> );
Query OK, 0 rows affected (0.61 sec)
Now you can insert some records in the table using insert command. The query is as follows −
mysql> insert into Limit0Demo(Name) values('David');
Query OK, 1 row affected (0.13 sec)
mysql> insert into Limit0Demo(Name) values('Larry');
Query OK, 1 row affected (0.24 sec)
mysql> insert into Limit0Demo(Name) values('Carol');
Query OK, 1 row affected (0.17 sec)
mysql> insert into Limit0Demo(Name) values('Bob');
Query OK, 1 row affected (0.12 sec)
mysql> insert into Limit0Demo(Name) values('John');
Query OK, 1 row affected (0.11 sec)
mysql> insert into Limit0Demo(Name) values('Sam');
Query OK, 1 row affected (0.11 sec)
mysql> insert into Limit0Demo(Name) values('James');
Query OK, 1 row affected (0.12 sec)
mysql> insert into Limit0Demo(Name) values('Maxwell');
Query OK, 1 row affected (0.13 sec)
mysql> insert into Limit0Demo(Name) values('Ricky');
Query OK, 1 row affected (0.09 sec)
mysql> insert into Limit0Demo(Name) values('Adam');
Query OK, 1 row affected (0.06 sec)Now you can display all records from the table using a select statement. The query is as follows −
mysql> select *from Limit0Demo;
The following is the output −
+----+---------+
| Id | Name |
+----+---------+
| 1 | David |
| 2 | Larry |
| 3 | Carol |
| 4 | Bob |
| 5 | John |
| 6 | Sam |
| 7 | James |
| 8 | Maxwell |
| 9 | Ricky |
| 10 | Adam |
+----+---------+
10 rows in set (0.00 sec)
Case 1: Use of limit 0.
The query is as follows −
mysql> select *from Limit0Demo limit 0;
Empty set (0.00 sec)
Case 2: When you want the specific number of rows from the table. The query is as follows −
mysql> select *from Limit0Demo limit 3;
The following is the output −
+----+-------+
| Id | Name |
+----+-------+
| 1 | David |
| 2 | Larry |
| 3 | Carol |
+----+-------+
3 rows in set (0.00 sec)
Published on 26-Feb-2019 12:26:33
