README.md

usp_DeleteDuplicates

SQL Server Stored Procedure to remove duplicate rows from a table.

This procedure removes EXACT duplicate values from a table. The table must not have any enforced unique constraints, as this makes removing duplicates unnecessary. If enforced unique constraint(s) exist on the table you can remove duplicate rows using @WithUniques = 1. I would really be careful with @WithUniques = 1.

For instance, let's say we have the following table:

MyDb.dbo.ExampleTable

LastName	FirstName
Doe	John
Doe	John
Doe	Jane
Doe	Jane

Now let's run our procedure:

EXECUTE dbo.usp_DeleteDuplicates @DatabaseName = N'MyDb',
				 @SchemaName = N'dbo',
				 @TableName = N'ExampleTable';

We are now left with:

MyDb.dbo.ExampleTable

LastName	FirstName
Doe	John
Doe	Jane

Parameter explanations:

@ObjectName     This requires the name of the object, allows for object
                pieces. (DatabaseName.SchemaName.TableName)

@WhatIf         0 = This is the default. This will remove the duplicates.
                1 = Hypothetically removes the duplicate rows. Does not
                    actually perform the delete, but displays the rows
                    that would be affected.

@WithUniques    0 = This is the default. This will check for enforced uniqueness.
                1 = This will remove all duplicates excluding the unique columns.

@DatabaseName   Which database is this table stored in?
                If NULL, this will use the current database context
                from where the procedure is being called.

@SchemaName     Which schema does this database belong?
                IF NULL, this will use the default schema of the caller.

@TableName      The table in which you are attempting to remove duplicate
                rows.