ADO: ActiveX Data Objects

Appendix A. Introduction to SQL

The SQL, or Structured Query Language, specification has many varieties. All are used for either data selection, data manipulation, or database modification. Through this language we can gracefully create queries, store procedures, filter recordsets, create tables -- you name it. Just about everything that you can do with a database, you can do with SQL.

In this appendix, you will learn the Microsoft Jet Engine SQL language. This form of SQL is very similar to the ANSI SQL specification. Differences exist between these two specifications in a number of places, the most important difference being datatypes. ANSI SQL and Microsoft use different names for datatypes. The SQL language described in this appendix uses the Microsoft datatypes, for obvious reasons.

Other differences arise when ANSI SQL conflicts with Microsoft standards. In addition, some functions have been removed from the ANSI standard by Microsoft because there are already ways to accomplish these functions through ADO. Also, some statements (listed next) are unique to Microsoft, including TRANSFORM, PARAMETERS, STDEV, and STDEVP. We will be taking a look at these statements and functions shortly.