Find the real column name of an alias used in a view?

sql, sql-server, t-sql

Solution

Given this view:

CREATE VIEW viewTest
AS
SELECT
    books.id,
    books.author,
    Books.title AS Name
FROM
    Books

What I can see you can get the columns used and the tables used by doing this:

SELECT * 
FROM INFORMATION_SCHEMA.VIEW_COLUMN_USAGE AS UsedColumns 
WHERE UsedColumns.VIEW_NAME='viewTest'

SELECT * 
FROM INFORMATION_SCHEMA.VIEW_TABLE_USAGE AS UsedTables 
WHERE UsedTables.VIEW_NAME='viewTest'

This is for sql server 2005+. See reference here

Edit

Give the same view. Try this query:

SELECT
    c.name AS columnName,
    columnTypes.name as dataType,
    aliases.name as alias
FROM 
sys.views v 
JOIN sys.sql_dependencies d 
    ON d.object_id = v.object_id
JOIN .sys.objects t 
    ON t.object_id = d.referenced_major_id
JOIN sys.columns c 
    ON c.object_id = d.referenced_major_id 
JOIN sys.types AS columnTypes 
    ON c.user_type_id=columnTypes.user_type_id
    AND c.column_id = d.referenced_minor_id
JOIN sys.columns AS aliases
    on c.column_id=aliases.column_id
    AND aliases.object_id = object_id('viewTest')
WHERE
    v.name = 'viewTest';

It returns this for me:

columnName  dataType  alias

id          int       id
author      varchar   author
title       varchar   Name

This is also tested in sql 2005+

Problem

Suppose I have a view in which some of the column names are aliases, like "surName" in this example: ``` CREATE VIEW myView AS SELECT firstName, middleName, you.lastName surName FROM myTable me LEFT OUTER JOIN yourTable you ON me.code = you.code GO ``` I'm able to retrieve some information about the view using the INFORMATION_SCHEMA views. For example, the query ``` SELECT column_name AS ALIAS, data_type AS TYPE FROM information_schema.columns WHERE table_name = 'myView' ``` yields: ``` ---------------- |ALIAS |TYPE | ---------------- |firstName |nchar| |middleName|nchar| |surName |nchar| ---------------- ``` However, I would like to know the actual column name as well. Ideally: ``` --------------------------- |ALIAS |TYPE |REALNAME | --------------------------- |firstName |nchar|firstName | |middleName|nchar|middleName| |surName |nchar|lastName | --------------------------- ``` How can I determine what the real column name is based on the alias? There must be some way to use the sys tables and/or INFORMATION_SCHEMA views to retrieve this information. EDIT: I can get close with this abomination, which is similar to Arion's answer: ``` SELECT c.name AS ALIAS, ISNULL(type_name(c.system_type_id), t.name) AS DATA_TYPE, tablecols.name AS REALNAME FROM sys.views v JOIN sys.columns c ON c.object_id = v.object_id LEFT JOIN sys.types t ON c.user_type_id = t.user_type_id JOIN sys.sql_dependencies d ON d.object_id = v.object_id AND c.column_id = d.referenced_minor_id JOIN sys.columns tablecols ON d.referenced_major_id = tablecols.object_id AND tablecols.column_id = d.referenced_minor_id AND tablecols.column_id = c.column_id WHERE v.name ='myView' ``` This yields: ``` --------------------------- |ALIAS |TYPE |REALNAME | --------------------------- |firstName |nchar|firstName | |middleName|nchar|middleName| |surName |nchar|code | |surName |nchar|lastName | --------------------------- ``` but the third record is wrong -- this happens with any view created using a "JOIN" clause, because there are two columns with the same "column_id", but in different tables.

Original source