How to Compare SQL Server Databases

All topics about maintaining SQL Server from a DBA perspective.
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sqltips
Posts: 6
Joined: Mon Jun 24, 2019 1:51 pm

Mon Jun 24, 2019 1:52 pm

Almost every database administrator would like to be able to compare the structures and data between the tables in the database or the whole databases themselves. As a result, many searched for ways on how they can simplify this procedure by simply having a stored procedure, which will contain two parameters only. These two parameters are the names of the first and the second databases. They should have the ability to compare the structures and the data and should tell you the differences. This is what the SQL server compare tools do. Now you do not have to do everything manually when it comes to analyzing, contrasting and documenting the databases in SQL server.

Since database administrators are very busy, they now have the chance to perform other actions and let a specialized tool do the work when they want to compare SQL. The utilities that can be used today can provide one with full control over the databases. Even if the databases belong in different servers, they can still be analyzed and compared effectively. The most important part here is that the tools are very useful when it comes to verifying the reliability and integrity of the database without worrying you about safety issues. This is because they will never affect the data that are stored in any database in your system. One significant factor that you should look at is the ability of the tool to perform comparisons and analysis but it should not be designed to modify or alter any data or structure.

On the other hand, there is also another method that you can apply. Instead of relying on the tools that you can obtain, you can simply write a stored procedure or SP. One of the most common notions when comparing the data and the structures between two databases is about implementation. The quickest solution for some is to create a cycle throughout all the tables and then compose SELECTs so that one can get the differences. However, there are some flaws that should not be neglected here. The first one is that the tables may or may not involve a unique key. This is because one can make out the differences when a table has a unique key.

Another issue is that prior to the data being compared, the first step is to compare the structures. Otherwise, it is like you will be comparing without being organized. Therefore, there is a need to make a valuable and clear report regarding the structural differences beforehand. In addition to this, the datatypes text as well as the image and the ntext cannot be utilized in a predicate. You should also look at the fact that there are some columns that are found in tables that store nulls. Albeit setting ANST_NULS OFF, there is no chance that you can get TRUE if you compare two nulls. While it is possible that you can compare two variables locally and get TRUE, comparing two columns that contain nulls will definitely return UNKNOWN. With stored procedure, you can solve these issues and compare SQL servers easily.
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