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Why we mention in MySQL WHERE 1=0?
The condition 1=0 can be used to stop the query from returning any rows. It returns empty set.
The syntax is as follows:
SELECT *FROM yourTableName WHERE 1=0;
To understand the above syntax,let us create a table. The query to create a table is as follows:
mysql> create table ConditionDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.59 sec)
Insert some records in the table using insert command. The query is as follows:
mysql> insert into ConditionDemo(Name) values('Larry');
Query OK, 1 row affected (0.10 sec)
mysql> insert into ConditionDemo(Name) values('Sam');
Query OK, 1 row affected (0.14 sec)
mysql> insert into ConditionDemo(Name) values('Mike');
Query OK, 1 row affected (0.13 sec)
mysql> insert into ConditionDemo(Name) values('Carol');
Query OK, 1 row affected (0.12 sec)
mysql> insert into ConditionDemo(Name) values('John');
Query OK, 1 row affected (0.17 sec)
mysql> insert into ConditionDemo(Name) values('Bob');
Query OK, 1 row affected (0.10 sec)Display all records from the table using select statement. The query is as follows:
mysql> select *from ConditionDemo;
The following is the output:
+----+-------+ | Id | Name | +----+-------+ | 1 | Larry | | 2 | Sam | | 3 | Mike | | 4 | Carol | | 5 | John | | 6 | Bob | +----+-------+ 6 rows in set (0.00 sec)
Here is the query to prevent the query from returning any row
mysql> select *from ConditionDemo where 1=0; Empty set (0.00 sec)
Updated on: 30-Jul-2019
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