Saturday, November 6, 2010

T SQL: UNABLE TO USE COLUMN ALIAS IN WHERE CLAUSE

Since I started working over T SQL I have faces many issues in query and resolved them by walking through blogs, however; one thing that I always thought about, was the reasons behind those issues.

One of those issues is that we can't use column alias in where clause, for instance:

SELECT SUM(CoustmerId) AS OrderCount ... WHERE OrderCount > 2000

We can't do this because in the execution order of an SQL statement SELECT clause executes after WHERE clause.

I thought that was the issue with T SQL compiler, however; later I figured out that the issue is not because of T SQL compiler but because of my lack of knowledge.

I hope this post will help people. Have a nice day.

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