Check Those Aliases

Kevin Feasel

2017-06-02

T-SQL

Erik Darling warns you about accidentally using the wrong alias in a query:

People will often tell you to clearly alias your tables, and they’re right. It will make them more readable and understandable to whomever has to read your code next, puzzling over the 52 self joins and WHERE clause that starts off with 1 = 2. It can also help solve odd performance problems.

Take this query, for instance.

This isn’t just for subqueries; even simple joins can go haywire when you accidentally use the wrong alias and both tables happen to have the same column name.

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