Contents
How do you define column alias in SELECT statement?
Aliases are often used to make column names more readable. An alias only exists for the duration of that query. An alias is created with the AS keyword.
Can I use alias in group by?
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.
Can we ORDER BY alias?
An alias can be used in a query select list to give a column a different name. You can use the alias in GROUP BY, ORDER BY, or HAVING clauses to refer to the column. Check here. Yes, you can certainly use column aliases in your “order by” clause.
Can we use alias in ORDER BY?
Due to logical query processing order, alias can be used in order by.
Is it possible to reference an alias in select?
You can’t reference an alias except in ORDER BY because SELECT is the second last clause that’s evaluated. Two workarounds: SELECT BalanceDue FROM ( SELECT (InvoiceTotal – PaymentTotal – CreditTotal) AS BalanceDue FROM Invoices ) AS x WHERE BalanceDue > 0;
When to use the alias keyword in SQL?
The AS keyword is optional. The alias effectively renames the select list item for the duration of the query. The alias can be used in the order_by_clause but not other clauses in the query. Not the answer you’re looking for?
How to use computed column alias in PostgreSQL?
I hit something like this migrating a 500+ line Netezza query (aka modified Postgres) to SQL Server. In Netezza the computed column alias was allowed to be used as a value in downstream references. My work around was to use CROSS APPLY with a correlated sub-query.
How to use computed column alias in Netezza?
In Netezza the computed column alias was allowed to be used as a value in downstream references. My work around was to use CROSS APPLY with a correlated sub-query. The beauty of it is that the numerous references to the column alias in original query did not need to be changed at all.