Comparing two SQL Server database schema in C#

Question

I am releasing a newer version of my Windows application. There are DB schema changes in the new version. Also I do not want to lose the data.

So the approach that I ha

Answer 1

We use SQL Compare from RedGate, but it's not particularly cheap.

SQL Compare

This lets us compare the structure of two databases, and creates a SQL script to update one of the databases to match the other.

Answer 2

Create your Database Migration scripts and run them with a tool such as Db Up to keep track of schema changes. SQL Scripts migrate your database from version 1 to 2, 2 to 3, etc. Schema Compare is another option mentioned in a previous question.

• Modify Customer Tables.sql
• Update Settings.sql

Answer 3

Here's a free way to compare databases.

Below is a SQL Server script I knocked up, which outputs the contents of your database's Stored Procedures, Views and Tables into the Output window.

You run it by calling:

exec [dbo].[ScriptStoredProcedures]

On many of my projects, I'll run this script, copy the text into a file in my Visual Studio project, so I can check-in a copy of how our database looked at a particular time.

(Yes, you can also have Database Projects within Visual Studio, but this is an alternative method.)

If you run this script on both of your database, you can compare the two outputs to find differences.

CREATE PROCEDURE [dbo].[ScriptStoredProcedures]
AS
BEGIN
    --
    --  Attempt to create a long SQL script, to Drop, then "CREATE PROCEDURE" on all SPs and "CREATE FUNCTION" on all Functions in this database. 
    --
    --  You can then run this script on a "target" database, and it'll have the latest Stored Procedures & functions
    --  created/updated on it.
    --
    --      exec [dbo].[ScriptStoredProcedures]
    --  
    SET NOCOUNT ON

    PRINT '--'
    PRINT '--  SQL Script, generated by the [ScriptStoredProcedures] Stored Procedure.'
    PRINT '--  Created on ' + convert(nvarchar, GetDate(), 106) + ' ' + convert(nvarchar, GetDate(), 108)
    PRINT '--'
    PRINT '--  This will create/update the Stored Procedures on this database, to bring them up-to-date with the SPs '
    PRINT '--  from the database ''' + DB_NAME() + ''' on the server ''' + @@SERVERNAME + ''''
    PRINT '--'
    PRINT '--'



    --  Create a temporary table, where each record contains one line of Stored Procedure/Function script
    --  (i.e. If you have a Stored Procedure with 30 lines of script in it, we'll create 30 temporary records
    --  to store it)
    CREATE TABLE #tmp 
    (
        [inx] INT IDENTITY(1, 1),
        [text] nvarchar(4000)
    )

    DECLARE @StoredProcedureName NVARCHAR(200)
    DECLARE @StoredProcedureType NVARCHAR(10)
    DECLARE @ExecCommand NVARCHAR(200)
    DECLARE @OneLineOfScript NVARCHAR(4000)

    --  First, get a list of all Stored Procedures & Functions in this database
    DECLARE cursorEachStoredProcedure CURSOR LOCAL FORWARD_ONLY STATIC READ_ONLY FOR 
    SELECT [name],              --  Name of the Stored Procedure or Function
           [type]               --  This will contain "FN" if it's a Function, or "P" if it's a Stored Procedure
    FROM sysobjects 
    WHERE (OBJECTPROPERTY(id, N'IsProcedure') = 1
      OR OBJECTPROPERTY(id, N'IsTableFunction') = 1
      OR OBJECTPROPERTY(id, N'IsScalarFunction') = 1
      OR OBJECTPROPERTY(id, N'IsView') = 1)
    AND [name] NOT LIKE 'sp_%'
    AND [name] NOT LIKE 'fn_%'
    ORDER BY [type] DESC,       --  Sort by Stored Procedures first, then functions
             [name]             --  then show the list of SPs/Functions in name order


    OPEN cursorEachStoredProcedure 
    FETCH NEXT FROM cursorEachStoredProcedure INTO @StoredProcedureName, @StoredProcedureType

    --  For each Stored Procedure we've found in our database, create some script to delete the Stored Procedure
    --  from the target database if it exists, then re-create it.
    WHILE (@@FETCH_STATUS = 0) 
    BEGIN 

        PRINT ''
        IF (@StoredProcedureType = 'P')
        BEGIN
            PRINT 'PRINT ''Creating stored procedure: ''''' + @StoredProcedureName + ''''''''
            PRINT ''
            PRINT 'IF EXISTS(select Name from sysobjects where OBJECTPROPERTY(id, N''IsProcedure'') = 1 AND Name = ''' + @StoredProcedureName + ''')'
            PRINT 'BEGIN'
            PRINT '   DROP PROCEDURE [' + @StoredProcedureName + '] '
            PRINT 'END'
        END
        ELSE
        IF (@StoredProcedureType = 'V')
        BEGIN
            PRINT 'PRINT ''Creating view: ''''' + @StoredProcedureName + ''''''''
            PRINT ''
            PRINT 'IF EXISTS(select Name from sysobjects where OBJECTPROPERTY(id, N''IsView'') = 1 AND Name = ''' + @StoredProcedureName + ''')'
            PRINT 'BEGIN'
            PRINT '   DROP VIEW [' + @StoredProcedureName + '] '
            PRINT 'END'
        END
        ELSE
        BEGIN
            PRINT 'PRINT ''Creating function: ''''' + @StoredProcedureName + ''''''''
            PRINT ''
            PRINT 'IF EXISTS(select Name from sysobjects where (OBJECTPROPERTY(id, N''IsTableFunction'') = 1 OR OBJECTPROPERTY(id, N''IsScalarFunction'') = 1) AND Name = ''' + @StoredProcedureName + ''')'
            PRINT 'BEGIN'
            PRINT '   DROP FUNCTION [' + @StoredProcedureName + '] '
            PRINT 'END'
        END         
        PRINT 'GO '

        --  Run the "sp_helptext" command, to get the text of this Stored Procedure (one row per *line* of script)
        --  and store this set of results in a temporary table, so we can step through, line-by-line, and send
        --  the output to the Messages window.
        SET @ExecCommand = 'sp_helptext @objname = ''' + @StoredProcedureName + ''''

        DELETE FROM #tmp

        INSERT INTO #tmp
        EXEC(@ExecCommand)

        --  Step through each line of this Stored Procedure
        DECLARE cursorEachLineOfScript CURSOR LOCAL FORWARD_ONLY STATIC READ_ONLY FOR 
        SELECT [text] 
        FROM #tmp
        ORDER BY [inx]

        OPEN cursorEachLineOfScript 
        FETCH NEXT FROM cursorEachLineOfScript INTO @OneLineOfScript

        WHILE (@@FETCH_STATUS = 0) 
        BEGIN 
            --  For each line of Stored Procedure script, send the text to the Messages window
            PRINT @OneLineOfScript

            FETCH NEXT FROM cursorEachLineOfScript INTO @OneLineOfScript
        END 
        CLOSE cursorEachLineOfScript 
        DEALLOCATE cursorEachLineOfScript   
        PRINT 'GO '

        FETCH NEXT FROM cursorEachStoredProcedure INTO @StoredProcedureName, @StoredProcedureType
    END

    CLOSE cursorEachStoredProcedure 
    DEALLOCATE cursorEachStoredProcedure    

    DROP TABLE #tmp 

    PRINT 'EXEC [dbo].[spGrantExectoAllStoredProcs]'
    PRINT 'GO'

    PRINT '--'
    PRINT '--'
    PRINT '--  List of tables (and their fields) in this database'
    PRINT '--'
    PRINT '--'
    PRINT '--'


    --  First, let's iterate through our list of tables, and find out which fields they contain.
    DECLARE 
        @tableName nvarchar(200),
        @fieldName nvarchar(500),
        @fieldType nvarchar(500),
        @fieldNullable nvarchar(200)

    DECLARE cursorTables CURSOR LOCAL FORWARD_ONLY STATIC READ_ONLY FOR 
    SELECT st.NAME as 'Table_name'
    FROM sys.tables st
    ORDER BY 1

    OPEN cursorTables 
    FETCH NEXT FROM cursorTables INTO @tableName

    WHILE (@@FETCH_STATUS = 0) 
    BEGIN
        PRINT '--  Table: ' + @tableName

        DECLARE cursorFields CURSOR LOCAL FORWARD_ONLY STATIC READ_ONLY FOR 
        SELECT sc.NAME as 'Field_name',
            case when t.Name in ('char', 'varchar', 'nvarchar') 
           then t.Name + '(' + cast(sc.max_length/2 as nvarchar) + ')' 
           else 
                case when t.Name in ('numeric') 
                    then t.Name + '(' + cast(sc.precision as nvarchar)  + ',' + cast(sc.scale as nvarchar) + ')'  
                    else t.Name 
                end
        end as 'Data_type',
        case when sc.is_nullable=1 then 'null' else 'not null' end as 'Nullable'
        FROM sys.tables st
        INNER JOIN sys.columns sc ON st.object_id = sc.object_id
        INNER JOIN sys.types t ON sc.system_type_id = t.system_type_id
        WHERE t.Name != 'sysname'
        AND st.name = @tableName
        ORDER BY 1, 2

        OPEN cursorFields 
        FETCH NEXT FROM cursorFields INTO @fieldName, @fieldType, @fieldNullable

        WHILE (@@FETCH_STATUS = 0) 
        BEGIN
            PRINT '--    ' + @fieldName + '  (' + @fieldType + ', ' + @fieldNullable + ')'
            FETCH NEXT FROM cursorFields INTO @fieldName, @fieldType, @fieldNullable
        END
        CLOSE cursorFields 
        DEALLOCATE cursorFields 

        PRINT '--'

        FETCH NEXT FROM cursorTables INTO @tableName
    END
    CLOSE cursorTables 
    DEALLOCATE cursorTables 
END

Answer 4

Two suggestions.

1. use the SQL Comparison SDK from Redgate (who I work for). This allows you programmatic access to the SQL Compare technology.
2. There must be a characteristic of a particular schema version you can check to determine which one it is? If so, you could run the appropriate script against that version to bring it to the next. Your installer just needs to include a chain of such migration scripts that get run in succession to take it to the next incremental version. Ideally you'd have version information embedded in the schema either via an extended property or in a version table, which gets updated upon successful application of a migration script.