Why and How to Compare SQL Files and Databases

SQL or structured query language is a computer language designed to retrieve and manage data in relational databases, creating and modifying database schema, and managing database object access controls. Managing databases often involves synchronizing different copies of a particular database system, whether on different machines or over time, and it often becomes necessary to compare SQL files.

Keeping track of the various changes that might be made to a particular database or SQL file is by no means an easy task. As databases are used, more and more information might be fed into the database, and more and more relations between the items arise. A database administrator wishing to keep track of the changes that are made will usually have no recourse but to use special programs to do so. Trying to manually find the differences between two databases may be possible if they are extremely small, but in real world practice, it is all but impossible!

One type of modification to a database involves the actual data contained therein. For example, a database might consist of detailed information about employees, and the human resources department would then be entitled to update this information regularly. Another example would be a financial database. In this case, it would most probably be the accounting department making constant changes to the information in the database, whether adding new items or adjusting existing data.

Another kind of modification to a database would involve modifications to its schema. The term schema refers to the formally encoded structure of a database, which can be considered its template or outline. In a schema, the different possible kinds of data items to be contained in the database are shown, along with their interrelationships and access controls. A database manager may find it necessary to improve upon existing schema for the sake of efficiency or clarity, for example.

Both of these changes may be done using SQL or other database management languages, and both of these kinds of changes may prove important to track. There are various kinds of tools that may be used to compare databases, but they all have some common features. For instance, most comparison tools have synchronization features, which mean that they can automatically keep two copies of a database identical through time. This is both in terms of the database structure or schema, and the actual data.

Database comparison tools are also usually able to give a visual comparison of two databases, making it easier for the administrator to track various changes. Many of them also come with built-in scripting capabilities, which make it possible to automatically run scripts to modify databases. Smart use of this feature could save a database administrator a lot of labor and time.

Databases are a ubiquitous part of today's business world, and the ability to compare SQL files and different databases is essential. Often, it is in the database administrators' best interests to learn to make good use of comparison tools in order to make their job easier and more efficient.