SQL (Structured Query Language) is a recognized standard language designed to organize, manage, and retrieve data from a database. SQL is essentially a programming language for relational databases, and over the past decade SQL Server has consistently delivered an reliable, scalable, cost-effective data management platform.

Why SQL?
In today’s economy, with corporations looking to control costs while still driving productivity higher, the cost of acquiring and maintaining a company’s software investments is in the spotlight. Information technology (IT) departments are under pressure to deliver more services, in shorter amounts of time, and with ever decreasing budgets. For these reasons, IT departments worldwide are choosing technologies that provide more business value at a lower cost. One example of a technology that is growing rapidly in IT departments is SQL Database.

Primary advantages of SQL:
- Portability (between database applications)
- Industry Standard (the de facto standard database query language)
- Dynamic data definition (it can handle alphanumerical queries in an optimized way)

Advantage of SQL over Access:

1) Reliability
With Access each client reads and writes directly to the raw data tables. If a client machine crashes while writing data this will usually cause the back-end database to also crash and become corrupt. The same thing will occur if the network fails, has a glitch or temporarily becomes overloaded. This problem becomes more apparent as the amount of data or the number of users increases.

With SQL Server the clients do not talk directly with the tables but with an intelligent data manager on the server. This in turn reads and writes data from and to the tables. If a client machine crashes, or the network hiccups, this will not affect the underlying tables; instead the data manager realises that the transaction has not been completed and does not commit the partially transmitted data to the database. The database therefore continues to run without problem.

The client/server system also maintains an automatic 'transaction log'. If a backup has to be restored the transaction log can be run and should restore all completed transactions up to the time of the crash.

The client/server software itself is designed for mission critical systems and is orders of magnitude more reliable than a file server system. On one system that we support the client used to experience around one to two crashes per year (admittedly their network was not exactly state of the art!) when running with an Access database. After we converted it to SQL Server two years ago the system has not experienced a single crash.

2) Data Integrity
Data integrity in SQL Server is enhanced by the use of 'triggers' which can be applied whenever a record is added, updated or deleted. This occurs at the table level and cannot thus be forgotten about, ignored or bypassed by the client machine. For example audit processes cannot be avoided (accidentally or deliberately) with this scenario.

3) Better Performance
With Access all tables involved in a form, report or a query are copied across the network from the server to the client's machine. The tables are then processed and filtered to generate the required recordset. For example if looking up details for one particular order from an orders table containing, say, 50,000 records then the whole table (all 50,000 records) is dragged over the network and then 49,999 of these records are thrown away (this is an over-simplification since indexing can be used to mitigate this to some extent). Contrast this with SQL Server where the filtering takes place on the server (if designed properly) and only 1 record is transmitted over the network.

This can affect performance in two ways. Firstly SQL Server is highly optimised and can usually perform the required filtering much more quickly than the client machine and secondly the amount of data sent across the network link is vastly reduced. For most databases the main performance bottleneck is data transmission over the network hence reducing this can give a really dramatic improvement in performance.

Predicting likely performance improvements is very difficult but an average overall speed improvement of 3 to 5 times, and possibly much more, would not be unexpected.

4) Network Traffic/Speed
As can be seen from the previous section, network traffic is greatly reduced in a client/server scenario, often by many orders of magnitude. This both improves network reliability (by reducing collisions, etc.) and also improves the performance of the network for other software (as there is less traffic on the network). Where there is a slow connection, such as over a telephone dial-up, Access is usually so slow as to be all but unusable (obviously this does depend upon the amount of data) whereas a SQL Server application, if designed for this environment, can still be perfectly useable.

5) Low Bandwidth
This occurs when you are accessing your database over a connection that only supports low data speeds, which, for all practical situations, means anything other than a LAN. In all low bandwidth situations Access/JET usually performs so slowly as to be unusable whilst a correctly designed SQL Server system can be similar in speed to running it over a LAN.

6) Scalability
A file-server system such as Access is designed for small workgroups and is scalable to perhaps 10 concurrent clients. Above this level performance starts to degrade rapidly as more users are added. With the SQL Server client/server architecture many hundreds, or even thousands (with the appropriate infrastructure), of concurrent users can be supported without significant performance degradation.