Compare columns of two tables and add missing - sql-server-2008

Question

Using SQL Server 2008 i have two tables: [Source] and [Target]
I want to check all columns of Source table and see if they exist in Target table.
If they dont exist then i want to add the columns.
I have created a procedure to fix this. The only thing im struggeling with is how to set the datatypes correctly.
I mean, if it is a varchar field i must specify the length. If its an int field i dont need to and so on. Is there a way to do this without creating seperate handeling of every datatype available?

Answer 1

This is incomplete... you'll have to handle the other datatypes that I forgot (I don't think I forgot any). However I did test it and it works.
So to answer your question, no, you have to handle the datatypes.
DECLARE #MasterTable SYSNAME,
#SlaveTable SYSNAME,
#txtSQL VARCHAR(max)
SELECT #MasterTable = 'orderheader',
#SlaveTable = 'orderheader2'
DECLARE #myTable TABLE
(
txtSQL VARCHAR(MAX)
)
INSERT INTO #myTable
(
[txtSQL]
)
SELECT 'ALTER TABLE [dbo].[' +
#SlaveTable +
'] ADD [' +
a.[name] +
'] [' +
typ.[name] +
']' +
CASE typ.[name]
WHEN 'decimal' THEN '(' + CAST(a.[precision] AS VARCHAR(20)) + ',' + CAST(a.[scale] AS VARCHAR(20)) + ')'
WHEN 'numeric' THEN '(' + CAST(a.[precision] AS VARCHAR(20)) + ',' + CAST(a.[scale] AS VARCHAR(20)) + ')'
WHEN 'varchar' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
WHEN 'char' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
WHEN 'nvarchar' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
WHEN 'nchar' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
WHEN 'binary' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
WHEN 'varbinary' THEN '(' + CAST(a.[max_length] AS VARCHAR(20)) + ')'
ELSE ''
END
FROM (
SELECT col.*
FROM sys.tables tbl
INNER JOIN sys.columns col
ON tbl.[object_id] = col.[object_id]
WHERE tbl.[name] = #MasterTable
) a
LEFT JOIN (
SELECT col.*
FROM sys.tables tbl
INNER JOIN sys.columns col
ON tbl.[object_id] = col.[object_id]
WHERE tbl.[name] = #SlaveTable
) b
ON a.[name] = b.[name]
INNER JOIN sys.types typ
ON a.[system_type_id] = typ.[system_type_id]
WHERE b.name IS NULL
WHILE EXISTS
(
SELECT TOP 1 1
FROM #myTable
)
BEGIN
SELECT TOP 1 #txtSQL = txtSQL FROM #myTable
DELETE FROM #myTable WHERE [txtSQL] = #txtSQL
EXEC (#txtSQL)
END

Answer 2

Is using SQL Compare from Red Gate out of the question?