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There are two ways:<br />
1. Use the case statement directly: <br />
SELECT CASE RefCode1 WHEN '' THEN RefCode2 ELSE RefCode1 END AS NewRefCode<br />
FROM Somwhere<br />
WHERE &nbsp;CASE RefCode1 WHEN '' THEN RefCode2 ELSE RefCode1 END = 'Something'<br />
<br />
2. Use a subtable<br />
SELECT A.NewRefCode<br />
FROM<br />
(<br />
SELECT CASE RefCode1 WHEN '' THEN RefCode2 ELSE RefCode1 END AS NewRefCode<br />
FROM Somwhere<br />
) A<br />
WHERE A.NewRefCode = 'Something' <br />
&nbsp;<br />
If the field contained NULL instead of a blank space you could dispense with the CASE statement and use ISNULL instead:<br />
SELECT ISNULL(RefCode, RefCode2) AS NewRefCode<br />
FROM Somwhere<br />
WHERE ISNULL(RefCode, RefCode2) = 'Something' <br />

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I have 2 tables with product reference codes that are then merged into one table column alias using the following statement...<br />
<br />
SELECT CASE RefCode1 WHEN '' THEN RefCode2 ELSE RefCode1 END AS NewRefCode<br />
<br />
This works fine by itself until i then need to filter the &quot;NewRefCode&quot; column, i can't use the WHERE NewRefCode = 'Example' statement without generating an error as it's not a real column.<br />
<br />
Is there a way around this without using something like WHERE Refcode1 OR Refcode2 = 'Example'<br />
<br />
Thanks
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I have 2 tables with product reference codes that are then merged into one table column alias using the following statement...

SELECT CASE RefCode1 WHEN '' THEN RefCode2 ELSE RefCode1 END AS NewRefCode

This works fine by itself until i then need to filter the "NewRefCode" column, i can't use the WHERE NewRefCode = 'Example' statement without generating an error as it's not a real column.

Is there a way around this without using something like WHERE Refcode1 OR Refcode2 = 'Example'

Thanks

Using a WHERE filter against a column ALIAS in SQL

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Microsoft SQL Server

SQL (Structured Query Language) is designed to be used in conjunction with relational database products as of a means of working with sets of data. SQL consists of data definition, data manipulation, and procedural elements. Its scope includes data insert, query, update and delete, schema creation and modification, and data access control.