Does it make sense to use “LIMIT 1” in a query “SELECT 1 …”?

Yes, you can use LIMIT 1 with SELECT1.

Suppose, you are using SELECT 1 and your table has billions of records. In this case, it will print 1 billion times.

The syntax of SELECT 1 is as follows −

SELECT 1 FROM yourTableName;

Suppose, you are using LIMIT 1 and your table has billions of records. This case, it will print 1 only once.

The syntax of SELECT 1 with LIMIT 1 is as follows −

SELECT 1 FROM yourTableName LIMIT 1;

To understand the above syntax, let us create a table. The query to create a table is as follows −

mysql> create table Select1AndLimit1Demo    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> Name varchar(20)    -> ); Query OK, 0 rows affected (1.99 sec)

Insert some records in the table using insert command. The query is as follows −

mysql> insert into Select1AndLimit1Demo(Name) values('John'); Query OK, 1 row affected (0.21 sec) mysql> insert into Select1AndLimit1Demo(Name) values('Carol'); Query OK, 1 row affected (0.14 sec) mysql> insert into Select1AndLimit1Demo(Name) values('Sam'); Query OK, 1 row affected (0.11 sec) mysql> insert into Select1AndLimit1Demo(Name) values('Bob'); Query OK, 1 row affected (0.18 sec) mysql> insert into Select1AndLimit1Demo(Name) values('David'); Query OK, 1 row affected (0.14 sec) mysql> insert into Select1AndLimit1Demo(Name) values('Mike'); Query OK, 1 row affected (0.20 sec) mysql> insert into Select1AndLimit1Demo(Name) values('Maxwell'); Query OK, 1 row affected (0.11 sec)

Display all records from the table using a select statement. The query is as follows −

mysql> select *from Select1AndLimit1Demo;

Output

+----+---------+ | Id | Name | +----+---------+ | 1 | John | | 2 | Carol | | 3 | Sam | | 4 | Bob | | 5 | David | | 6 | Mike | | 7 | Maxwell | +----+---------+ 7 rows in set (0.00 sec)

Here is the case of SELECT 1. The query is as follows −

mysql> select 1 from Select1AndLimit1Demo;

Output

+---+ | 1 | +---+ | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | +---+ 7 rows in set (0.00 sec)

Above, we have a table with 7 records. Therefore, the output is 7 times 1.

Let us now see the case of SELECT 1 with LIMIT 1. The query is as follows −

mysql> select 1 from Select1AndLimit1Demo limit 1;

The following is the output displaying the value 1 only once −

+---+ | 1 | +---+ | 1 | +---+ 1 row in set (0.00 sec)

Above, our table has 7 records. We are getting 1 times 1 because we have used LIMIT 1.