Select comma separated string depending on existing columns - sql

Question

I have a table in my database which have a set of bit value columns. I want to insert a comma separated string in a new column, depending on the values of these bit columns.
Lets say the columns are named:
c1,c2,c3,c4
If the value in a column is equal to 1, I want to include the string mapped as following:
c1: 'campaign1'
c2: 'campaign2'
c3: 'campaign3'
c4: 'campaign4'
So for exampel, if a row contains the following values:
c1 = 1, c2 = 0, c3 = 1, c4 = 0
I want to insert the following in a new column named 'Campaigns'
'campaign1,campaign3'
Any suggestions on how I can accomplish this?

Answer 1

I would do this using stuff() and some string manipulation:
select t.*,
stuff( ((case when c1 = 1 then ',campaign1' else '' end) +
(case when c2 = 1 then ',campaign2' else '' end) +
(case when c3 = 1 then ',campaign3' else '' end) +
(case when c4 = 1 then ',campaign4' else '' end)
), 1, 1, ''
) as campaigns
from t;

Answer 2

This works, but it might not best the best solution:
DECLARE #table TABLE (id INT, c1 INT, c2 INT, c3 INT, c4 INT);
INSERT INTO #table
SELECT 1, 1, 0, 1, 0
UNION ALL
SELECT 2, 0, 0, 1, 1;
WITH cte AS (
SELECT
id,
CASE WHEN c1 = 1 THEN 'campaign1,' ELSE '' END +
CASE WHEN c2 = 1 THEN 'campaign2,' ELSE '' END +
CASE WHEN c3 = 1 THEN 'campaign3,' ELSE '' END +
CASE WHEN c4 = 1 THEN 'campaign4,' ELSE '' END AS campaigns
FROM
#table)
SELECT
id,
CASE
WHEN LEN(campaigns) > 0 THEN LEFT(campaigns, LEN(campaigns) - 1)
ELSE ''
END AS campaigns
FROM
cte;
Gordon beat me to the STUFF method, which I was hastily writing when I realised this was better, but here's an answer that also shows how the UPDATE might work, as this is what you originally asked for:
DECLARE #table TABLE (id INT, c1 INT, c2 INT, c3 INT, c4 INT, campaigns VARCHAR(512));
INSERT INTO #table
SELECT 1, 1, 0, 1, 0, NULL
UNION ALL
SELECT 2, 0, 0, 1, 1, NULL;
UPDATE
t
SET
campaigns = STUFF(CASE WHEN c1 = 1 THEN ',campaign1' ELSE '' END +
CASE WHEN c2 = 1 THEN ',campaign2' ELSE '' END +
CASE WHEN c3 = 1 THEN ',campaign3' ELSE '' END +
CASE WHEN c4 = 1 THEN ',campaign4' ELSE '' END, 1, 1, '')
FROM
#table t;
SELECT * FROM #table;
Results:
id c1 c2 c3 c4 campaigns
1 1 0 1 0 campaign1,campaign3
2 0 0 1 1 campaign3,campaign4

Answer 3

Just to give another option, you can use concat and replace also
DECLARE #table TABLE (id INT, c1 INT, c2 INT, c3 INT, c4 INT)
INSERT INTO #table
SELECT 1, 1, 0, 1, 0 UNION ALL SELECT 2, 0, 0, 1, 1
select t.*,
replace(replace(c1, '1', 'Campaing1,'), '0', '') +
replace(replace(c2, '1', 'Campaing2,'), '0', '') +
replace(replace(c3, '1', 'Campaing3,'), '0', '') +
replace(replace(c4, '1', 'Campaing4,'), '0', '')
from #table t
The result is
id c1 c2 c3 c4 COLUMN1
-- -- -- -- -- -------
1 1 0 1 0 Campaing1,Campaing3,
2 0 0 1 1 Campaing3,Campaing4,
But I would go for Gordon's answer

Answer 4

You may use IIF function ( provided you're using SQL Server 2012+ ) as in the following :
select IIF(c1=1, 'Campaign1', '')+IIF(c2=1 and c1>0,',','')+
IIF(c2=1, 'Campaign2', '')+IIF(c3=1 and c1+c2>0,',','')+
IIF(c3=1, 'Campaign3', '')+IIF(c4=1 and c1+c2+c3>0,',','')+
IIF(c4=1, 'Campaign4', '') as 'Campaigns'
from tab t;
SQL Fiddle Demo