CODEWITHSUNDEEP
sqlsql-servert-sqlpivot
markA
markA

Reputation: 1609

How do I use Dynamic SQL to Generate Groups of Columns?

People like to get different types and amounts of fruit and I want to help them. I have a table that looks like this:

name    fruit   count   temp
-----------------------------
Jim     apple    3      hot
Jim     banana   7      cold
Jim     orange   12     cold
Sam     plum     5      hot
Sam     peach    1      hot
Bob     cherry   4      cold
Bob     banana   11     hot
Bob     orange   9      cold
Bob     kiwi     6      hot

Each person could have 1 or 1000 rows and I will not know how many ahead of time so I think this requires dynamic column lists. I need it to look like this:

name    fruit_1 count_1 temp_1  fruit_2 count_2 temp_2  fruit_3 count_3 temp_3  fruit_4 count_4 temp_4
-------------------------------------------------------------------------------------------------------
Jim     apple     3      hot    banana    7      cold   orange    12     cold   null     null   null
Sam     plum      5      hot    peach     1      hot    null     null    null   null     null   null
Bob     cherry    4      cold   banana    11     hot    orange     9     cold   kiwi      6     hot

The code from PIVOT in sql 2005 works for parsing out one column when you don't know how many rows there will be, but I can't get it to work for multiple columns. I tried creating extra @select_list variables, and I can use that to create the columns, but I can't get the data I want in them and I don't know how to interweave the order like I want (eg f1,c1,t1,f2,c2,t2 vs f1,f2,c1,c2,t1,t2 etc)

Here is the code I have been unsuccessfully trying to tweak:

CREATE TABLE #stackoverflowTest(
    [name] [varchar](3) NOT NULL,
    [fruit] [varchar](12) NOT NULL,
    [number] [int] NOT NULL,
    [temp] [varchar](4) NOT NULL)

INSERT INTO #stackoverflowTest
VALUES ('Jim','apple',3,'hot'),
    ('Jim','banana',7,'cold'),
    ('Jim','orange',12,'cold'),
    ('Sam','plum',5,'hot'),
    ('Sam','peach',1,'hot'),
    ('Bob','cherry',4,'cold'),
    ('Bob','banana',11,'hot'),
    ('Bob','orange',9,'cold'),
    ('Bob','kiwi',6,'hot')


DECLARE @sql AS varchar(max)
DECLARE @pivot_list AS varchar(max)
DECLARE @select_list AS varchar(max) 

SELECT @pivot_list = COALESCE(@pivot_list + ', ', '') + '[' + CONVERT(varchar, PIVOT_CODE) + ']'
    ,@select_list = COALESCE(@select_list + ', ', '') + '[' + CONVERT(varchar, PIVOT_CODE) + '] AS [fruit_' + CONVERT(varchar, PIVOT_CODE) + ']'
FROM (
    SELECT DISTINCT PIVOT_CODE
    FROM (
        SELECT name, fruit, number, temp, ROW_NUMBER() OVER (PARTITION BY name ORDER BY name,number) AS PIVOT_CODE
        FROM #stackoverflowTest
    ) AS rows
) AS PIVOT_CODES

SET @sql = '
;WITH p AS (
    SELECT name, fruit, number, temp, ROW_NUMBER() OVER (PARTITION BY name ORDER BY name,number) AS PIVOT_CODE
    FROM #stackoverflowTest
)
SELECT name, ' + @select_list + '
FROM p
PIVOT (
    MIN(fruit)
    FOR PIVOT_CODE IN (
        ' + @pivot_list + '
    )
) AS pvt
'
EXEC (@sql)

Upvotes: 3

Views: 477

Answers (1)

Matt Whitfield
Matt Whitfield

Reputation: 6574

I wouldn't really try using PIVOT for that, it gets into a headmess situation pretty quickly.

This is probably simpler:

DECLARE @sql AS varchar(max)
DECLARE @select_list AS varchar(MAX) 

SELECT @select_list = ISNULL(@select_list + ', ', '') + 'SUM(CASE WHEN PIVOT_CODE = ' + [PIVOT_CODE] + ' THEN number ELSE NULL END) AS number_' + [PIVOT_CODE] + ', MIN(CASE WHEN PIVOT_CODE = ' + [PIVOT_CODE] + ' THEN temp ELSE NULL END) AS temp_' + [PIVOT_CODE] + ', MIN(CASE WHEN PIVOT_CODE = ' + [PIVOT_CODE] + ' THEN fruit ELSE NULL END) AS fruit_' + [PIVOT_CODE]
FROM (
    SELECT DISTINCT PIVOT_CODE
    FROM (
        SELECT name, fruit, number, temp, CONVERT(varchar(20), ROW_NUMBER() OVER (PARTITION BY name ORDER BY NAME,number)) AS PIVOT_CODE
        FROM #stackoverflowTest
    ) AS rows
) AS PIVOT_CODES

SET @sql = '
;WITH p AS (
    SELECT name, fruit, number, temp, ROW_NUMBER() OVER (PARTITION BY name ORDER BY name,number) AS PIVOT_CODE
    FROM #stackoverflowTest
)
SELECT name, ' + @select_list + '
FROM p GROUP BY name'
EXEC (@sql)

Upvotes: 5

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