Writing a dynamic SQL query that splits the contents of a column

Posted on 2008-06-09
Last Modified: 2010-03-19
I have a database in SQL Server 2005. There are 4 columns in the database that are of relevance to my question, we'll call them Combined, A, B, and C. These columns contain measurements, where all 4 are varchar fields.

I need to loop through about 3500 records where Combined is populated but A, B, and C are not. So, basically what I need to do is take the string contained within Combined, which will look something like:
11" x 22" x 3-1/4", split it, trim it, and take just the numeric portions of the combined string and put them in their corresponding cells. So, in this instance, 11 would go in A, 22 would go in B and 3-1/4 would go in C. By trimming, I mean the ", x and whitespace would all be removed.

I would imagine this is rather a simple query to write, but my T-SQL is mediocre at best. Can anyone help me write a query to do this?

Question by:nuvium

Author Comment

ID: 21746468
Wait, before anyone answers this question, I just doublechecked my notes, and I HAVE IT BACKWARDS. The basis of what im trying to do is the same (and I definitely still need help with the query), but I have it in the opposite order!

Instead, I have the three columns, A, B and C populated with numbers. (using the above example, 11, 22, 3-1/4). I need to instead of split it, combine it using the following format : 11" x 22" 3-1/4".

So the formula is Number 1(") white space (x) white space Number 2(")  (x) Number 3(")

Instead of splitting one column into 3, I am combining 3 columns into one.
LVL 19

Expert Comment

ID: 21746599

See code below (assuming your table name is T)
select A,B,C, A + ' X ' + B + ' X ' + C  as D from T

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LVL 69

Expert Comment

ID: 21746621
Add a computed column to the table (once) to materialize that column whenever it is needed.

ALTER TABLE tablename
    ADD compoundColumn AS colA + '" x ' + colB + '" x ' + colC + '"'

From then on, use that name just like any other col, for example:

SELECT compoundColumn
FROM tablename
WHERE compoundColumn LIKE '%...%'
ORDER BY compoundColumn
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Expert Comment

ID: 21746646
If the fields are int (or any other format) you will need to do this:

select cast(A as varchar) + ' X ' + cast(B as varchar) + ' X ' + cast(C as varchar) as D from T


Accepted Solution

floook earned 500 total points
ID: 21747512
To account for blank values and nulls in any of the columns you'll need something like this:

UPDATE tableName
   SET Combined =

            WHEN LEN(isNull(A, '')) > 0 THEN A + '" x '
            ELSE ''


             WHEN LEN(isNull(B, '')) > 0 THEN B + '" x '
             ELSE ''


             WHEN LEN(isNull(C, '')) > 0 THEN C + '"'
             ELSE ''

I ran it on a sample table and the results are as follows:

A      B      C      Combined
11      22      3-1/4      11" x 22" x 3-1/4"
1.5      1-1/2      10      1.5" x 1-1/2" x 10"
1.5      NULL      10      1.5" x 10"
      NULL      10      10"

* The last row under A contains an empty string.

Adding a computed column as suggested by ScottPletcher is a good idea if you need to keep the Combined column up-to-date at all times. You'll still have to account for nulls and empty strings in your source columns though.


Expert Comment

ID: 21747669
I forgot to trim the output string so:

UPDATE tableName
 SET Combined = RTIM( ... )

This will take care of case where column C (or B and C) is blank or null.
UPDATE tableName

 SET Combined = RTIM( ... )

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