What’s this ‘WHERE 1=1’?

Since some time I have been adding WHERE 1=1 to all my queries.
I get queries like this:

SELECT *
  FROM emp e
 WHERE 1=1
   AND e.ename LIKE 'A%'
   AND e.deptno = 20

Lots of people ask me what’s the use of this WHERE 1=1.

You know I like to type as little as possible but here I am typing a lot of extra characters. And yet, it makes my development life a lot easier.

If my query has a lot of predicates and I want to see what happens then I usually comment those predicates out by using — (two dashes). I use my own CommentLine plug-in for this. This is easy for the second and higher predicates. But if I want to comment out the first predicate, then it get a bit harder. Well, not harder, but more work.

If I didn’t use the WHERE 1=1 and I wanted to comment out the ename predicate then I would have to do something like this:

SELECT *
  FROM emp e
 WHERE /*e.ename LIKE 'A%'
   AND */e.deptno = 20

I agree, it’s not hard to do, but I think it’s a lot more work than just adding — (two dashes) in front of a line:

SELECT *
  FROM emp e
 WHERE 1 = 1
--   AND e.ename LIKE 'A%'
   AND e.deptno = 20

And, as I don’t like typing or at least, I want to make it as easy for me as possible, I am using another one of my plug-ins, Template, where I defined a template w1 which results in

WHERE 1 = 1
   AND 


making it easy for me to write the queries.

I think adding this extra predicate has no (or hardly any) influence on the execution time of the query. I think the optimizer ignores this predicate completely.

I hope this explains a bit why I write my queries like this.

One thought on “What’s this ‘WHERE 1=1’?

  1. I use Wher 1 = 1 in application when composing queries. This way I will just keep appending “AND XXX=YYY” knowing that there is a first condition 1= 1


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