Sql-server – Compare and auto fix conflicts between two databases T-sql

sql servert-sql

Consider we have a database for an windows application it's for 2 years ago, now we have changed many things in database so there is differences and we don't know what are the differences.

I don't want to use compare tools like Red Gate compare tool.

What's the best way to see new columns are in new database :

Query result like :

New Db Name | Schema | Table Name | Column Name | Default Value | IsNullable | DataType
NewDb       | dbo    | myTable    | newColumn   | ''            | No         | nvarchar(30)

Thank you

Edit :
I need a query after this to fix the conflicts so both databases be the same :

Add NewDb columns to OldDb,delete OldDb columns that are not in NewDb and update all columns to NewDb version ( if two columns datatype or something is different in two databases. set the NewDb's to OldDb too.)

Best Answer

Columns in old database but not in new , or default value, nullable and data type changed:

SELECT t1.*,
       t2.*
FROM   [OldDb].[INFORMATION_SCHEMA].[COLUMNS] t1
       LEFT JOIN [NewDb].[INFORMATION_SCHEMA].[COLUMNS] t2
         ON t1.COLUMN_NAME = t2.COLUMN_NAME
WHERE  t2.COLUMN_NAME IS NULL
        OR ( t1.TABLE_NAME = t2.TABLE_NAME
             AND t1.TABLE_SCHEMA = t2.TABLE_SCHEMA
             AND t1.COLUMN_NAME = t2.COLUMN_NAME
             AND ( t1.DATA_TYPE != t2.DATA_TYPE
                    OR t1.IS_NULLABLE != t2.IS_NULLABLE
                    OR t1.CHARACTER_MAXIMUM_LENGTH != t2.CHARACTER_MAXIMUM_LENGTH
                    OR t1.COLUMN_DEFAULT != t2.COLUMN_DEFAULT ) )
ORDER  BY t1.COLUMN_NAME

Columns in new database but not in old :

You can change [OldDb] place with [NewDb] in query

I wrote this question and answer because I've needed this and I've spent so much of time on this.

So I hope everyone can find and use this easily :). I'm looking forward for opinions for make this better.

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