What is the purpose of using WHERE 1=1 in SQL statements?
Possible Duplicates:
Why would a sql query have “where 1 = 1”
Why would someone use WHERE 1=1 AND <conditions> in a SQL clause?
I've seen that a lot in different query examples and it goes to probably all SQL engines.
If there is a query that has no conditions defined people (and specially ORM frameworks) often add always-true condition WHERE 1 = 1 or something like that.
So instead of
SELECT id, name FROM users;
they use
SELECT id, name FROM users WHERE 1 = 1;
The only possible reason I could think of if you are adding conditions dynamically you don't have to worry about stripping the initial AND but still quite often this 1 = 1 condition is stripped if there is an actual condition in the query.
Actual example from CakePHP (generated by framework):
(no conditions)
SELECT `User`.`id`, `User`.`login`
FROM `users` AS `User` WHERE 1 = 1
ORDER BY `User`.`id` ASC;
(with condition)
SELECT `User`.`id`, `User`.`login`
FROM `users` AS `User`
WHERE `User`.`login` = '[email protected]'
LIMIT 1;
Is there any reason for adding that extra condition?
Answer
It's also a common practice when people are building the sql query programmatically, it's just easier to start with 'where 1=1 ' and then appending ' and customer.id=:custId' depending if a customer id is provided. So you can always append the next part of the query starting with 'and ...'.