What does it mean by select 1 from MySQL table?

MySQLMySQLi Database

The statement ‘select 1’ from any table name means that it returns only 1. For example, If any table has 4 records then it will return 1 four times.

Let us see an example. Firstly, we will create a table using the CREATE command.

mysql> create table StudentTable
   -> (
   -> id int,
   -> name varchar(100)
   -> );
Query OK, 0 rows affected (0.51 sec)

Inserting records

mysql> insert into StudentTable values(1,'John'),(2,'Carol'),(3,'Smith'),(4,'Bob');
Query OK, 4 rows affected (0.21 sec)
Records: 4  Duplicates: 0  Warnings: 0

To display all the records.

mysql> select *from StudentTable;

Here is the output.

+------+-------+
| id   | name  |
+------+-------+
|    1 | John  |
|    2 | Carol |
|    3 | Smith |
|    4 | Bob   |
+------+-------+
4 rows in set (0.00 sec)

The following is the query to implement "select 1".

mysql> select 1 from StudentTable;

Here is the output.

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

The above returns 1 four times for 4 records, and if we had 5 records then the above query would have returned 1 five times.

Note: It returns 1 N times, if the table has N records.
raja
Published on 21-Nov-2018 12:54:52
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