Offshore Software Outsourcing Company, offshore IT outsourcing services, offshore software development Russia

About ALTOROS: ALTOROS Systems is headquartered in Tampa, Florida and maintains an office near Boston, Massachusetts and technology development center in Belarus and Russia. ALTOROS specializes on providing value-added e-commerce and web-based software development and offshore software outsourcing services to emerging enterprises helping them successfully plan and implement business initiatives.

You can use an alias to refer to a column in the GROUP BY, ORDER BY, or in the HAVING part. Aliases can also be used to give columns better names:

SELECT SQRT(a*b) as rt FROM table_name GROUP BY rt HAVING rt > 0;
SELECT id,COUNT(*) AS cnt FROM table_name GROUP BY id HAVING cnt > 0;
SELECT id AS "Customer identity" FROM table_name;

Note that ANSI SQL doesn't allow you to refer to an alias in a WHERE clause. This is because when the WHERE code is executed the column value may not yet be determined. For example, the following query is illegal:

SELECT id,COUNT(*) AS cnt FROM table_name WHERE cnt > 0 GROUP BY id;

The WHERE statement is executed to determine which rows should be included in the GROUP BY part while HAVING is used to decide which rows from the result set should be used.