How to create a temp table from a dynamic list - sql

Question

I have a table FieldList (ID int, Title varchar(50)) and want to create a temp table with a column list for each record in FieldList with the column name = FieldList.Title and the type as varchar.
This all happens in a Stored Proc, and the temp table is returned to the client for reporting and data analysis.
e.g.
FieldList Table:
ID Title
1 City
2 UserSuppliedFieldName
3 SomeField
Resultant Temp table columns:
City UserSuppliedFieldName SomeField

Answer 1

You can use the following proc to do what you are wanting. It just requires that you:
Create the Temp Table before calling the proc (you will pass in the Temp Table name to the proc). This allows the temp table to be used in the current scope as Temp Tables created in Stored Procedures are dropped once that proc ends / returns.
Put just one field in the Temp Table; the datatype is irrelevant as the field will be dropped (you will pass in the field name to the proc)
[Be sure to change the proc name to whatever you like, but the temp proc name is used in the example that follows]
CREATE PROCEDURE #Abracadabra
(
#TempTableName SYSNAME,
#DummyFieldName SYSNAME,
#TestMode BIT = 0
)
AS
SET NOCOUNT ON
DECLARE #SQL NVARCHAR(MAX)
SELECT #SQL = COALESCE(#SQL + N', [',
N'ALTER TABLE ' + #TempTableName + N' ADD [')
+ [Title]
+ N'] VARCHAR(100)'
FROM #FieldList
ORDER BY [ID]
SET #SQL = #SQL
+ N' ; ALTER TABLE '
+ #TempTableName
+ N' DROP COLUMN ['
+ #DummyFieldName
+ N'] ; '
IF (#TestMode = 0)
BEGIN
EXEC(#SQL)
END
ELSE
BEGIN
PRINT #SQL
END
GO
The following example shows the proc in use. The first execution is in Test Mode that simply prints the SQL that will be executed. The second execution runs the SQL and the SELECT following that EXEC shows that the fields are what was in the FieldList table.
/*
-- HIGHLIGHT FROM "SET" THROUGH FINAL "INSERT" AND RUN ONCE
-- to setup the example
SET NOCOUNT ON;
--DROP TABLE #FieldList
CREATE TABLE #FieldList (ID INT, Title VARCHAR(50))
INSERT INTO #FieldList (ID, Title) VALUES (1, 'City')
INSERT INTO #FieldList (ID, Title) VALUES (2, 'UserSuppliedFieldName')
INSERT INTO #FieldList (ID, Title) VALUES (3, 'SomeField')
*/
IF (OBJECT_ID('tempdb.dbo.#Tmp') IS NOT NULL)
BEGIN
DROP TABLE #Tmp
END
CREATE TABLE #Tmp (Dummy INT)
EXEC #Abracadabra
#TempTableName = N'#Tmp',
#DummyFieldName = N'Dummy',
#TestMode = 1
-- look in "Messages" tab
EXEC #Abracadabra
#TempTableName = N'#Tmp',
#DummyFieldName = N'Dummy',
#TestMode = 0
SELECT * FROM #Tmp
Output from #TestMode = 1:
ALTER TABLE #Tmp ADD [City] VARCHAR(100), [UserSuppliedFieldName]
VARCHAR(100), [SomeField] VARCHAR(100) ; ALTER TABLE #Tmp DROP COLUMN
[Dummy] ;

Answer 2

Create this function and pass to it the list you require. It will generate a table for you temporarily that you can use in real-time with any other SQL query. I've provided an example as well.
CREATE FUNCTION [dbo].[fnMakeTableFromList]
(#List varchar(MAX), #Delimiter varchar(255))
RETURNS table
AS
RETURN (SELECT Item = CONVERT(VARCHAR, Item)
FROM (SELECT Item = x.i.value('(./text())[1]', 'varchar(max)')
FROM (SELECT [XML] = CONVERT(XML, '<i>' + REPLACE(#List, #Delimiter, '</i><i>') + '</i>').query('.')) AS a
CROSS APPLY [XML].nodes('i') AS x(i)) AS y
WHERE Item IS NOT NULL);
GO
And you can use it like this ...
Parm1 = a list in a string seperated by a delimiter
Parm2 = the delimiter character
SELECT *
FROM fnMakeTableFromList('a,b,c,d,e',',')
Result is a table ...
a
b
c
d
e

Answer 3

With previously created table "FieldList" with fields "ID" and "Title"...
step 1: create table. The field "First" is there just to have one field, we'll delete it at the end
create table #SOE (First varchar(50))
step 2: right click and select "Result To - > Result to text", then run query:
select 'alter table #SOE add ' + Title + ' varchar(50)' from dbo.FieldList
step 3: copy-paste result and execute it
step 4: delete first field
alter table #SOE drop column First
step 5: here is your table
select * from #SOE