Find Differences between two tables at column level

Question

Hi,
I have 2 tables one live table and the other History table..
If i have to find differences between live table and the latest version in the History table and also find which column got chaanged
How would i do that for a table which has many columns and i need each column for which the value has changed for a id
for ex:
  Table 1   (LIve)                           Table 2 (History)
ID col1     col2    Version               ID       col1     col2    Version
 1   ABC     123     V1                     1       ABCD   123     v2
 2   NBS     1234   V1                     2        NBS     123     V2
Result set should be 
Result Set:
ID col which changed
1    col1
2    col2   
Because the values for that column had been changed
Except gives me all the differences not just the column level ..

Answer 1

The dynamic version using schema views... :D
--Build a coulple OF testing tables to play with
CREATE TABLE dbo.Table1 (
ID INT IDENTITY(1,1) PRIMARY KEY,
Col1 INT,
Col2 INT,
Col3 INT
CREATE TABLE dbo.Table2 (
ID INT IDENTITY(1,1) PRIMARY KEY,
Col1 INT,
Col2 INT,
Col3 INT
INSERT dbo.Table1 (Col1,Col2,Col3) VALUES
(123,456,789),
(111,222,333),
(444,555,666),
(777,888,999),
(321,345,769),
(179,753,758),
(362,362,236),
(856,874,896),
(821,729,324)
INSERT dbo.Table2 (Col1,Col2,Col3) VALUES
(123,456,789),
(111,999,333), --col2 diff
(444,555,666),
(777,888,999),
(321,345,123), --col3 diff
(179,753,758),
(362,362,236),
(234,874,896), --col1 diff
(821,729,324)
And then the actual solution...
DECLARE
@t1 VARCHAR(10) = 'Table1',
@t2 VARCHAR(10) = 'Table2'
IF OBJECT_ID('tempdb..#temp') IS NOT NULL DROP TABLE #temp
SELECT
c.TABLE_SCHEMA,
c.TABLE_NAME,
c.COLUMN_NAME,
c.ORDINAL_POSITION,
CASE WHEN u.COLUMN_NAME IS NOT NULL THEN 1 ELSE 0 END AS PK
INTO #temp
FROM
INFORMATION_SCHEMA.COLUMNS c
JOIN INFORMATION_SCHEMA.TABLES t
ON c.TABLE_NAME = t.TABLE_NAME
AND c.TABLE_SCHEMA = t.TABLE_SCHEMA
LEFT JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE u
ON c.COLUMN_NAME = u.COLUMN_NAME
AND c.TABLE_NAME = u.TABLE_NAME
AND c.TABLE_SCHEMA = u.TABLE_SCHEMA
AND OBJECTPROPERTY(OBJECT_ID(constraint_name), 'IsPrimaryKey') = 1
WHERE 1 = 1
AND t.TABLE_TYPE = 'BASE TABLE'
AND c.TABLE_NAME IN (@t1,@t2)
ORDER BY
c.TABLE_SCHEMA, c.TABLE_NAME, c.ORDINAL_POSITION
DECLARE @select VARCHAR(MAX)
SELECT @select = COALESCE(@select + ', ', '') + t.TABLE_SCHEMA + '.' + t.TABLE_NAME + '.' + t.COLUMN_NAME
FROM #temp AS t
ORDER BY t.TABLE_NAME, t.ORDINAL_POSITION
DECLARE @from VARCHAR(MAX)
SELECT @from = COALESCE(@from + ' FULL JOIN ', '') + t.TABLE_SCHEMA + '.' + t.TABLE_NAME
FROM #temp AS t
WHERE t.PK = 1
ORDER BY t.TABLE_NAME
DECLARE @on VARCHAR(MAX)
SELECT @on = COALESCE(@on + ' = ', '') + t.TABLE_SCHEMA + '.' + t.TABLE_NAME + '.' + t.COLUMN_NAME
FROM #temp AS t
WHERE t.PK = 1
ORDER BY t.TABLE_NAME, t.ORDINAL_POSITION
DECLARE @where VARCHAR(MAX)
SELECT @where = COALESCE(@where + CASE WHEN t.TABLE_NAME = @t1 THEN ' OR ' ELSE ' <> ' END, '') + t.TABLE_SCHEMA + '.' + t.TABLE_NAME + '.' + t.COLUMN_NAME
FROM #temp AS t
WHERE t.PK = 0
ORDER BY t.ORDINAL_POSITION, t.TABLE_NAME
DECLARE @sql VARCHAR(MAX) = '
SELECT ' + @select + '
FROM ' + @from + '
ON ' + @on + '
WHERE ' + @where
EXEC (@sql)
HTH,
Jason