Datatypes and Functions Compared

Overview

Most of us work with more than one database system, and often we have to make those systems talk to one another. Knowing the compatible functions and datatypes is essential. Unfortunately, that's easier said than done. The following tables will help you quickly find counterpart functions and data- types for the four systems we use throughout this book: SQL Server, Access, Oracle, and MySQL.

Not every function and datatype has an equivalent function or datatype in each system, so there are gaps. We've left those gaps so you can fill in your custom solutions for future reference. For instance, you might use the Access FORMAT() function to truncate values. In this case, you would enter FORMAT(value,code) as the Access equivalent to the MySQL and Oracle truncating functions, TRUNCATE and TRUNC, respectively. We didn't list this function because it returns a string, not a number. Consequently, it isn't a good match for our purposes, but it might be fine for yours. Also keep in mind that where equivalents are listed, they are rarely exactly alike. You'll still want to refer to the particular system's documentation, but at least you'll know where to start.