Apr 3, 2009 · With PostgreSQL 9.3+ OR Oracle 12c, there is now lateral join that allows creating an alias. Lateral joins are joints inside witch you can reference preceding tables. SELECT col1, col2,col3 FROM MyTable m JOIN LATERAL ( SELECT SUBSTRING(m.Column1, 1, 4) + SUBSTRING(Column1, 4, 3) AS Col1 ) x ON true WHERE Col1 = 'MySearch'

I'm curious to know how people are using table aliases. The other developers where I work always use table aliases, and always use the alias of a, b, c, etc. Here's an example: SELECT a.TripNum, b.

SQL Server doesn't allow you to reference the alias in the GROUP BY clause because of the logical order of processing. The GROUP BY clause is processed before the SELECT clause, so the alias is not known when the GROUP BY clause is evaluated. This also explains why you can use the alias in the ORDER BY clause.

For me, the simplest way to use an ALIAS in the WHERE clause is to create a sub-query and select from it instead. Example: WITH Q1 AS ( SELECT LENGTH(name) AS name_length, id, name FROM any_table ) SELECT id, name, name_length FROM Q1 WHERE name_length > 0

Nov 1, 2016 · When I read SQL, I like to know exactly what I'm selecting when I read it; aliases actually confuse me more because I've got to slog through lines of columns before I actually get to the table name, which generally represents information about the data that the alias doesn't.

Apr 2, 2024 · You might find W3Schools "SQL Alias" to be of good help. Here is an example from their tutorial: SELECT po.OrderID, p.LastName, p.FirstName FROM Persons AS p, Product_Orders AS po WHERE p.LastName='Hansen' AND p.FirstName='Ola' Regarding using the Alias further in the query, depending on the database you are using it might be possible.

MSDN states that there are 4 steps in creating a server alias: In SQL Server Configuration Manager, expand SQL Server Native Client Configuration, right-click Aliases, and then click New Alias. In the Alias Name box, type the name of the alias. …

Feb 2, 2012 · You don't alias a table, you alias an instance of a table reference. This allows self joins, etc as you have mutliple instances of references to the same physical table. It's not a case where each AS gives that table a new name elsewhere, it's just an alias to refer to That particular reference. In your case, there are two show stoppers...

May 23, 2014 · If you DO use an alias, make it something obvious and easy to understand WITHOUT having to refer back to "FROM" clause - and again, something ideally with semantic meaning. "a" is bad. "p" is bad (among other reasons many tables in a join could start with "p". "pos" is OK if your table name is "position_tracking" and nothing else in the query ...

In the case of nested tables, some DBMS require to use an alias like MySQL and Oracle but others do not have such a strict requirement, but still allow to add them to substitute the result of the inner query.