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Oct 23, 2012 · The SQL-Server docs says: column_alias can be used in an ORDER BY clause, but it cannot be used in a WHERE, GROUP BY, or HAVING clause. Similar in the MySQL doc it says: Standard SQL disallows references to column aliases in a WHERE clause.
Normally you can't refer to field aliases in the WHERE clause. (Think of it as the entire SELECT including aliases, is applied after the WHERE clause.) But, as mentioned in other answers, you can force SQL to treat SELECT to be handled before the WHERE clause.
SQL aliases are used to give a table, or a column in a table, a temporary name. 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.
Nov 10, 2010 · BUT: SELECT CONCAT(names, surname) AS x FROM clients HAVING x LIKE '%a%' works, while SELECT CONCAT(names, surname) AS x FROM clients WHERE x LIKE '%a%' fails ("Unknown column 'x' in 'where clause'")
May 18, 2021 · An SQL alias is useful for simplifying your queries and making the query and its result more readable. This article explains why and how you can use aliases in your SQL queries. You can temporarily rename a table or a column by giving it another name. This is known as an SQL alias.
Mar 3, 2024 · It’s crucial to remember that aliases defined in a SELECT statement can’t be referenced in the WHERE clause of the same SELECT statement. To filter based on an alias, I’d need to use a subquery or a HAVING clause if dealing with aggregate functions.
SQL alias allows you to assign a table or a column a temporary name during the execution of a query. SQL has two types of aliases: table and column aliases.
SQL aliases are temporary names assigned to a table or column for the duration of a particular SQL query. They make SQL queries more readable, especially when dealing with complex joins and subqueries, and can save you a significant amount of typing in larger queries. Why Use SQL Aliases? There are three key reasons to use SQL aliases:
Jun 10, 2023 · What is an alias in SQL? It’s a name you give to a column or a table in your SQL query to make it easier to display the results or to write your query. SQL aliases are a useful feature and are available in all major database vendors, including Oracle, SQL Server, MySQL, PostgreSQL.
The SQL WHERE Clause. The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition. Example. Select all customers from Mexico: SELECT * FROM Customers. WHERE Country='Mexico'; Try it Yourself » Syntax. SELECT column1, column2, ... FROM table_name. WHERE condition;
