How to generate temp table columns and datatypes a

Question

I create temp tables quite often in SQL and I am looking into a way to generate the column names and datatypes automatically for the table definition so I don't have to look them all up everytime.

For example I run:

SELECT CustomerID
  ClientID,
  FirstName
  LastName
INTO #Test
From dbo.Customer

To initially setup the temp table with the appropriate columns and data I need. Once I get that all done, I then go back in and take out the INTO statement and write the following:

CREATE TABLE #Test
(
...
...
);

I want to find a way to auto generate the column names and datatypes from the initial creation of the temp table. Right now, since I am initially inserting into an automatically created temp table, I use this:

EXEC tempdb..sp_help '#Test';

This gives me everything I need without having to look all the column datatypes up, but I wanted to know if there was a way to just auto gen the column names off of something like this. So the auto gen would generate:

CustomerID int,
ClientID int,
FirstName varchar(50),
LastName varchar(50)

This would allow me to just copy and paste this into my create table statement.

Answer 1

this might give you a start:

DECLARE @viewname VARCHAR(50);
SET @viewname ='tableorviewname';
SELECT  c.name + ' '+ t.name + 
case t.name  
WHEN 'varchar' THEN '('+CAST(c.max_length AS VARCHAR(3) )+'),'
ELSE ',' 
end
FROM sys.columns c
INNER JOIN sys.types AS t ON c.system_type_id = t.system_type_id
WHERE object_id = (SELECT object_id from sys.objects where name = @viewname)
ORDER BY c.column_id

EDIT: TEMP TABLES:

temp tables are slightly different, for instance this works in sql 2008 for a temp table named #tv_source

DECLARE @viewortablename VARCHAR(50);
SET @viewortablename ='tempdb..#tv_source';
SELECT  c.name + ' '+ t.name + 
case t.name  
WHEN 'varchar' THEN '('+CAST(c.max_length AS VARCHAR(3) )+'),'
ELSE ',' 
end
FROM tempdb.sys.columns c
INNER JOIN sys.types AS t ON c.system_type_id = t.system_type_id
WHERE object_id =  object_id(@viewortablename)
ORDER BY c.column_id

NOTES: this gives a comma separated list, but did NOT attempt to remove that last comma, it gives only a list, which you would likely want to put on a string and manipulate, etc. then use as a dynamic sql or somthing. Still, it should give you a start on what you wish to do.

NOTE for to others, sql 2000 would not display the lengths properly for instance on a varchar(45), it would just list the varchar part and I did not attempt to rework that for this question.

Answer 2

...I've created a function that can output the list of columns and datatypes, if the object is a table, if that is something that would be useful for you?

CREATE FUNCTION [dbo].[fnDiscoverColumns]
( @PObjectName NVARCHAR(300) )

RETURNS @Data TABLE ( ColumnList NVARCHAR(350) )

AS
BEGIN

DECLARE @PObjectID TABLE  ( [object_id] INT )
INSERT @PObjectID ( [object_id] )

SELECT [object_id] FROM sys.objects AS O WHERE O.name = @PObjectName AND O.type = 'U'

DECLARE @PObjectDetails TABLE ( [RowNo] INT,[ColumnName] NVARCHAR(300),[XType] INT,[DataType] NVARCHAR(100),[system_type_id] INT,[user_type_id] INT,[MaxLength] NVARCHAR(5),[Precision] INT,[Scale] INT,[ColumnList] NVARCHAR(300) )

INSERT @PObjectDetails ( [RowNo],[ColumnName],[XType],[DataType],[system_type_id],[user_type_id],[MaxLength],[Precision],[Scale],[ColumnList] )

SELECT DISTINCT
ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS 'RowNo',
C.name AS 'ColumnName',
T.xtype AS 'XType',
UPPER(T.name) AS 'DataType',
C.system_type_id,
C.user_type_id,
CASE WHEN C.max_length < 0 THEN 'MAX' ELSE CAST(C.max_length AS VARCHAR) END AS 'MaxLength',
C.precision AS 'Precision',
C.scale AS 'Scale',
CASE
WHEN [XType] IN (34,35,36,40,48,52,56,58,59,60,61,62,98,99,104,122,127,189,240,241) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +',' 
WHEN [XType] IN (106,108) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +'('+ CAST([Precision] AS VARCHAR) +','+ CAST(C.scale AS VARCHAR) +'),'
WHEN [XType] IN (41,42,43,165,167,173,175,231,239) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +'('+ CASE WHEN C.max_length < 0 THEN 'MAX'  WHEN C.max_length > 1 THEN CAST(C.max_length / 2 AS VARCHAR) ELSE CAST(C.max_length AS VARCHAR) END +'),' ELSE NULL END AS 'ColumnList'
FROM sys.all_columns AS C
JOIN systypes AS T ON C.system_type_id = T.xusertype
WHERE C.object_id = (SELECT * FROM @PObjectID)  --373576369

--Return column names and data types
INSERT @Data
SELECT 'CREATE TABLE #ColumnsList ('

INSERT @Data
SELECT 
CASE WHEN C.RowNo = (SELECT MAX(RowNo) FROM @PObjectDetails) THEN LEFT(C.ColumnList, ABS(LEN(C.ColumnList + ',') - 2)) ELSE C.ColumnList END AS 'GeneratedColumns'     
FROM @PObjectDetails AS C

INSERT @Data
SELECT ')'

RETURN
END
GO

Once committed to the database, run it like this:

SELECT * FROM [dbo].[fnDiscoverColumns] ('ExecutionLogStorage') --name of table

This should give you an output like this:

CREATE TABLE #ColumnsList (
[LogEntryId]  BIGINT,
[InstanceName]  NVARCHAR(38),
[ReportID]  UNIQUEIDENTIFIER,
[UserName]  NVARCHAR(260),
[ExecutionId]  NVARCHAR(64),
[RequestType]  TINYINT,
[Format]  NVARCHAR(26),
[Parameters]  NTEXT,
[ReportAction]  TINYINT,
[TimeStart]  DATETIME,
[TimeEnd]  DATETIME,
[TimeDataRetrieval]  INT,
[TimeProcessing]  INT,
[TimeRendering]  INT,
[Source]  TINYINT,
[Status]  NVARCHAR(40),
[ByteCount]  BIGINT,
[RowCount]  BIGINT,
[AdditionalInfo]  XML
)

Answer 3

SELECT
', ['+ac.name+'] '+Type_Name(User_type_id)+
CASE WHEN Type_Name(User_type_id) = 'Decimal' 
      THEN +'('+CONVERT(Varchar(4),ac.Precision)+','+CONVERT(Varchar(4),ac.Scale)+')' 
      WHEN Type_Name(User_type_id) IN 
            ('tinyint','smallint','int','real','money','float','numeric','smallmoney','DateTime') 
      THEN ''
      ELSE +'('+CONVERT(Varchar(4),ac.Max_Length)+')' 
END AS TableColumn
FROM Tempdb.sys.all_columns AS ac
      INNER JOIN Tempdb.Sys.SysObjects AS so
            ON so.ID = ac.Object_ID
WHERE 1 = 1
AND so.Name = '##YourTempTableGoesHere'