When I was writing this blog post I had a hard time to come up with the title of the blog post so I did my best to come up with one. Here is the reason why? I wrote a blog post earlier SQL SERVER – Find First Non-Numeric Character from String. One of the questions was that how that blog can be useful in real life scenario. This blog post is the answer to that question. Let us first see a problem.

We have a table which has a column containing alphanumeric data. The data always has first as an integer and later part as a string. The business need is to order the data based on the first part of the alphanumeric data which is an integer. Now the problem is that no matter how we use ORDER BY the result is not produced as expected. Let us understand this with example.

Prepare a sample data:

-- How to find first non numberic character
USE tempdb
GO
CREATE TABLE MyTable (ID INT, Col1 VARCHAR(100))
GO
INSERT INTO MyTable (ID, Col1)
SELECT 1, '1one'
UNION ALL
SELECT 2, '11eleven'
UNION ALL
SELECT 3, '2two'
UNION ALL
SELECT 4, '22twentytwo'
UNION ALL
SELECT 5, '111oneeleven'
GO
-- Select Data
SELECT *
FROM MyTable
GO

The above query will give following result set.

Now let us use ORDER BY COL1 and observe the result along with Original SELECT.

-- Select Data
SELECT *
FROM MyTable
GO
-- Select Data
SELECT *
FROM MyTable
ORDER BY Col1
GO

The result of the table is not as per expected.

We need the result in following format.

Here is the good example of how we can use PATINDEX.

-- Use of PATINDEX
SELECT ID,
LEFT(Col1,PATINDEX('%[^0-9]%',Col1)-1) 'Numeric Character',
Col1 'Original Character'
FROM MyTable
ORDER BY LEFT(Col1,PATINDEX('%[^0-9]%',Col1)-1)
GO

We can use PATINDEX to identify the length of the digit part in the alphanumeric string (Remember: Our string has a first part as an int always. It will not work in any other scenario). Now you can use the LEFT function to extract the INT portion from the alphanumeric string and order the data according to it.

You can easily clean up the script by dropping following table.

DROP TABLE MyTable
GO

Here is the complete script so you can easily refer it.

-- How to find first non numberic character
USE tempdb
GO
CREATE TABLE MyTable (ID INT, Col1 VARCHAR(100))
GO
INSERT INTO MyTable (ID, Col1)
SELECT 1, '1one'
UNION ALL
SELECT 2, '11eleven'
UNION ALL
SELECT 3, '2two'
UNION ALL
SELECT 4, '22twentytwo'
UNION ALL
SELECT 5, '111oneeleven'
GO
-- Select Data
SELECT *
FROM MyTable
GO
-- Select Data
SELECT *
FROM MyTable
ORDER BY Col1
GO
-- Use of PATINDEX
SELECT ID,
Col1 'Original Character'
FROM MyTable
ORDER BY LEFT(Col1,PATINDEX('%[^0-9]%',Col1)-1)
GO
DROP TABLE MyTable
GO

Well, isn’t it an interesting solution. Any suggestion for better solution? Additionally any suggestion for changing the title of this blog post?

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL String, SQL Tips and Tricks, T SQL, Technology