December 24, 2014 at 9:45 am
I have a table that looks like this ...
idtype_codephone_num
11111-111-1111
12222-222-2222
21111-111-1111
32222-222-2222
I want to merge the data to look like this ...
idphone1 phone2
1111-111-1111222-222-2222
2111-111-1111NULL
3NULL222-222-2222
Basically if the type code is 1 one then move the data to column phone1, if the type is 2 then move it to column phone2.
This would be fairly simple if we always have type codes 1 and 2. But sometimes we can have type 1 and not type 2, or we could have type 2 and not type1.
Right now we only have 2 type codes. But, in the future we could be adding a 3rd type. So that would add a 3rd column (phone3).
Below is my code that I have written. I move the data into a temp table then list it. I am thinking of making this a view to my table. It works just fine. My question is, is there a better and more efficient way of doing this?
CREATE TABLE #Contacts (
id INT PRIMARY KEY,
phone1 VARCHAR(15),
phone2 VARCHAR(15)
)
-- Insert the records for type 1
INSERT INTO #Contacts
SELECT id,
phone_num,
NULL
FROM test1
WHERE type_code = '1'
-- Insert the records for type 2, if the id does not exist for type 1
INSERT INTO #Contacts
SELECT id,
NULL,
phone_num
FROM test1
WHERE NOT EXISTS (
SELECT 1
FROM #Contacts
WHERE #Contacts.id = test1.id
)
AND test1.type_code = '2'
-- if the id has both type 1 and 2, update the phone2 column with the data from type 2
UPDATE #Contacts
SET phone2 = test1.phone_num
FROM #contacts
JOIN test1 ON test1.id = #Contacts.id
WHERE type_code = '2'
SELECT id, phone1, phone2
FROM #Contacts
DROP TABLE #Contacts
December 24, 2014 at 9:54 am
I'd vote against a denormalized table. Stick with your current design at the table level.
If needed for an application layer you could use a pivoted view to display it in the format you described.
Something like
SELECT
id,
MAX(CASE WHEN type_code = 1 THEN phone_num ELSE NULL END) AS phone1,
MAX(CASE WHEN type_code = 2 THEN phone_num ELSE NULL END) AS phone2
FROM test1
GROUP BY id
December 24, 2014 at 10:03 am
That's perfect. So simple.
Thank you.
Viewing 3 posts - 1 through 2 (of 2 total)
You must be logged in to reply to this topic. Login to reply