What is the use of WHERE 1=0 in SQL [duplicate]

Question

Why do we write WHERE 1=0 or 1=1 in SQL query under WHERE clause?

Usually it's there by code generators that need to have a WHERE clause and a base condition that's always true or false. — siride
– siride, Commented Mar 6, 2017 at 4:48
Another question (first result from google): stackoverflow.com/questions/9140606/… — default locale
– default locale, Commented Mar 6, 2017 at 4:50
To avoid confusion - this 'duplicate' marking should be corrected from the 1=1 reference, to the correct 1=0 duplicate as in the previous comment. I would suggest to reopen, and then again marking it as duplicate using the correct reference. Even though the body of the question rephrases the question to both 1=0 and 1=1, the 1=0 question has better quality answers that reflect those both scenarios as well. — YoYo
– YoYo, Commented Aug 20, 2018 at 15:53

AndreFeijo · Accepted Answer · 2017-03-06 04:49:37Z

It's just used to make it easier to concatenate extra conditions to the WHERE clause. For example:

var sql = "SELECT * FROM Person WHERE 1=1 "; if(something) sql += " AND Something = 1"; if(somethingElse) sql += " AND SomethingElse = 1";

This way you don't need to check if it is the first condition or not, you can always append AND at the start.

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