Parsing T-SQL Queries

I’ve wondered at one point what happens when I click the little “Parse” button inside SSMS. The result is that the query is checked for syntax errors, but what really happens?

It is amazingly simple: The query executed in SQL Server is:

SET PARSEONLY ON
select dbo.Category.CategoryId from dbo.Category
SET PARSONLY OFF

Yup. that’s all there is to it.