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Generate SQL MERGE statements with Table data

This system stored procedure takes a table name as a parameter and generates a MERGE statement containing all the table data.

This is useful if you need to migrate static data between databases, eg. the generated MERGE statement can be included in source control and used to deploy data between DEV/TEST/PROD.

The stored procedure itself is installed within the [master] database as a system object, allowing the proc to be called within the context of user databases (e.g. EXEC Northwind.dbo.sp_generate_merge 'Region')

Key features:

  • Include or exclude specific columns from output (eg. exclude DateCreated/DateModified columns)
  • Only update the target database when changes in the source data are found
  • Support for larger tables (gets around character limitations in some SQL clients)

How Does it Work?

The generated MERGE statement populates the target table to match the source data. This includes the removal of any excess rows that are not present in the source.

When the generated MERGE statement is executed, the following logic is applied based on whether a match is found:

  • If the source row does not exist in the target table, an INSERT is performed
  • If a given row in the target table does not exist in the source, a DELETE is performed
  • If the source row already exists in the target table and has changed, an UPDATE is performed
  • If the source row already exists in the target table but the data has not changed, no action is performed (configurable)

Use Cases

  • Generate statements for static data tables, store the .SQL file in source control/add it to a Visual Studio Database Project and use it as part of your Dev/Test/Prod deployments. The generated statements are re-runnable, so you can make changes to the file and easily migrate those changes between environments.
  • Generate statements from your Production tables and then run those statements in your Dev/Test environments. Schedule this as part of a SQL Job to keep all of your environments in-sync.
  • Enter test data into your Dev environment, and then generate statements from the Dev tables so that you can always reproduce your test database with valid sample data.

Acknowledgements

This procedure was adapted from sp_generate_inserts, written by Narayana Vyas Kondreddi (http://vyaskn.tripod.com). I made a number of attempts to get in touch with Vyas but unfortunately have not been able to reach him. No copyright infringement is intended and I will of course respect his wishes if asks for this to be removed.

I would also like to acknowledge:

Installation

Simply execute the script, which will install it in [master] database as a system procedure (making it executable within user databases).

Known Limitations

This procedure has explicit support for the following datatypes: (small)datetime(2), (n)varchar, (n)text, (n)char, int, float, real, (small)money, timestamp, rowversion, uniqueidentifier and (var)binary. All others are implicitly converted to their CHAR representations so YMMV depending on the datatype. Additionally, this procedure has not been extensively tested with UNICODE datatypes.

The Image datatype is not supported and an error will be thrown if these are not excluded using the @cols_to_exclude parameter.

Usage

  1. Ensure that your SQL client is configured to send results to grid.
  2. Execute the proc, providing the source table name as a parameter
  3. Click the hyperlink within the resultset.
  4. Copy the SQL (excluding the Output tags) and paste into a new query window to execute.

Example

To generate a MERGE statement containing all data within the Person.AddressType table, excluding the ModifiedDate and rowguid columns:

EXEC AdventureWorks.dbo.sp_generate_merge @schema = 'Person', @table_name ='AddressType', @cols_to_exclude = '''ModifiedDate'',''rowguid'''

###Output

SET NOCOUNT ON
GO 
SET IDENTITY_INSERT [Person].[AddressType] ON
GO
MERGE INTO [Person].[AddressType] AS Target
USING (VALUES
  (1,'Billing')
 ,(2,'Home')
 ,(3,'Main Office')
 ,(4,'Primary')
 ,(5,'Shipping')
 ,(6,'Contact')
) AS Source ([AddressTypeID],[Name])
ON (Target.[AddressTypeID] = Source.[AddressTypeID])
WHEN MATCHED AND (
    NULLIF(Source.[Name], Target.[Name]) IS NOT NULL OR NULLIF(Target.[Name], Source.[Name]) IS NOT NULL) THEN
 UPDATE SET
 [Name] = Source.[Name]
WHEN NOT MATCHED BY TARGET THEN
 INSERT([AddressTypeID],[Name])
 VALUES(Source.[AddressTypeID],Source.[Name])
WHEN NOT MATCHED BY SOURCE THEN 
 DELETE;

SET IDENTITY_INSERT [Person].[AddressType] OFF
GO
SET NOCOUNT OFF
GO