How can I dynamically create columns in SQL select statement - sql

Question

I have 3 tables. Team, Option, OptionTeam.
The Team holds a TeamId and Name
Option holds OptionId, OptionGroup
OptionTeam holds TeamId, OptionId, OptionGroup
select a.TeamId, a.Name
(select count(*) from OptionTeam ot where ot.TeamId=a.TeamId and ot.OptionGroup=4) as Option1,
(select count(*) from OptionTeam ot where ot.TeamId=a.TeamId and ot.OptionGroup=5) as Option2,
(select count(*) from OptionTeam ot where ot.TeamId=a.TeamId and ot.OptionGroup=6) as Option3,
(select count(*) from OptionTeam ot where ot.TeamId=a.TeamId and ot.OptionGroup=11) as Option4
from Team a
I want to get a list of Teams, and extra columns indicating how many options of each group are connected to each Team. This is done by the above query, but I want to replace the 4,5,6,11 with values of OptionGroup from a table Option.
It has to be dynamic, because there might be a new OptionGroup in the future, and I want the stored procedure to be able to handle it.
Sample data:
Team
TeamId
1
2
3
Option
OptionId | OptionGroup
11 | 4
12 | 5
13 | 4
14 | 4
15 | 5
OptionTeam
TeamId | OptionId | OptionGroup
1 | 11 | 4
1 | 13 | 4
2 | 12 | 5
2 | 14 | 4
3 | 15 | 5
And the list I want to get is
TeamId | Group4 (OptionGroup=4) | Group5 (OptionGroup=5)
1 | 2 | 0
2 | 1 | 1
3 | 0 | 1

Answer 1

You'll need a dynamic pivot to do this. Here's the stored procedure:
CREATE PROC [dbo].[pivotsp]
#query AS NVARCHAR(MAX), -- The query, can also be the name of a table/view.
#on_rows AS NVARCHAR(MAX), -- The columns that will be regular rows.
#on_cols AS NVARCHAR(MAX), -- The columns that are to be pivoted.
#agg_func AS NVARCHAR(257) = N'SUM', -- Aggregate function.
#agg_col AS NVARCHAR(MAX), -- Column to aggregate.
#output AS NVARCHAR(257) = N'', -- Table for results
#debug AS bit = 0 -- 1 for debugging
AS
-- Example usage:
-- exec pivotsp
-- 'select * from vsaleshistory',
-- 'market,marketid,family,familyid,Forecaster,Forecasterid,product,productid',
-- 'month',
-- 'sum',
-- 'ku',
-- '##sales'
-- Input validation
IF #query IS NULL OR #on_rows IS NULL OR #on_cols IS NULL
OR #agg_func IS NULL OR #agg_col IS NULL
BEGIN
RAISERROR('Invalid input parameters.', 16, 1);
RETURN;
END
-- Additional input validation goes here (SQL Injection attempts, etc.)
BEGIN TRY
DECLARE
#sql AS NVARCHAR(MAX),
#cols AS NVARCHAR(MAX),
#newline AS NVARCHAR(2);
SET #newline = NCHAR(13) + NCHAR(10);
-- If input is a valid table or view
-- construct a SELECT statement against it
IF COALESCE(OBJECT_ID(#query, N'U'),
OBJECT_ID(#query, N'V')) IS NOT NULL
SET #query = N'SELECT * FROM ' + #query;
-- Make the query a derived table
SET #query = N'(' + #query + N') AS Query';
-- Handle * input in #agg_col
IF #agg_col = N'*'
SET #agg_col = N'1';
-- Construct column list
SET #sql =
N'SET #result = ' + #newline +
N' STUFF(' + #newline +
N' (SELECT N'','' + quotename( '
+ 'CAST(pivot_col AS sysname)' +
+ ') AS [text()]' + #newline +
N' FROM (SELECT DISTINCT('
+ #on_cols + N') AS pivot_col' + #newline +
N' FROM' + #query + N') AS DistinctCols' + #newline +
N' ORDER BY pivot_col' + #newline +
N' FOR XML PATH(''''))' + #newline +
N' ,1, 1, N'''');'
IF #debug = 1
PRINT #sql
EXEC sp_executesql
#stmt = #sql,
#params = N'#result AS NVARCHAR(MAX) OUTPUT',
#result = #cols OUTPUT;
IF #debug = 1
PRINT #cols
-- Create the PIVOT query
IF #output = N''
begin
SET #sql =
N'SELECT *' + #newline +
N'FROM (SELECT '
+ #on_rows
+ N', ' + #on_cols + N' AS pivot_col'
+ N', ' + #agg_col + N' AS agg_col' + #newline +
N' FROM ' + #query + N')' +
+ N' AS PivotInput' + #newline +
N' PIVOT(' + #agg_func + N'(agg_col)' + #newline +
N' FOR pivot_col IN(' + #cols + N')) AS PivotOutput;'
end
ELSE
begin
set #sql = 'IF EXISTS (SELECT * FROM tempdb.sys.objects WHERE ' +
'name = ''' + #output + ''' AND type = N''U'') DROP TABLE tempdb.' + #output
EXEC sp_executesql #sql;
SET #sql =
N'SELECT * INTO ' + #output + #newline +
N'FROM (SELECT '
+ #on_rows
+ N', ' + #on_cols + N' AS pivot_col'
+ N', ' + #agg_col + N' AS agg_col' + #newline +
N' FROM ' + #query + N')' +
+ N' AS PivotInput' + #newline +
N' PIVOT(' + #agg_func + N'(agg_col)' + #newline +
N' FOR pivot_col IN(' + #cols + N')) AS PivotOutput;'
end
IF #debug = 1
PRINT #sql
EXEC sp_executesql #sql;
END TRY
BEGIN CATCH
DECLARE
#error_message AS NVARCHAR(2047),
#error_severity AS INT,
#error_state AS INT;
SET #error_message = ERROR_MESSAGE();
SET #error_severity = ERROR_SEVERITY();
SET #error_state = ERROR_STATE();
RAISERROR(#error_message, #error_severity, #error_state);
RETURN;
END CATCH
With that, it's easy to pivot on a variable number of columns:
EXEC pivotsp
'SELECT TeamID, OptionGroup, OptionID AS Options FROM OptionTeam',
'Teamid', -- Row headers
'optiongroup', -- item to aggregate
'count', -- aggregation function
'optiongroup', -- Column header
'##temp' -- output table name
SELECT * FROM ##temp
Results:
Teamid 4 5
1 2 0
2 1 1
3 0 1

Answer 2

SELECT a.*, o.optionGroup, COUNT(*)
FROM team a
CROSS JOIN
option o
JOIN OptionTeam ot
ON ot.teamId = a.teamId
AND ot.optionGroup = o.optionGroup
WHERE o.OptionId = #id
GROUP BY
a.teamId, o.optionGroup

Answer 3

select teamID,
sum(case when optionGroup = 4 then 1 else 0 end) as optionGroup4,
sum(case when optionGroup = 5 then 1 else 0 end) as optionGroup5,
from optionteam
group by teamID
to add more optiongroups without changing the code, try grouping by that field:
select teamID,optionGroup,count(optionID) as optionCount
from optionteam
group by teamID,optionGroup