First what is data access? ADO? A Deer a female deer? SQL? You are confusing me here.... don't worry it's not as hard as it sounds...

ADO (Activex Data Object) - its the data access component of Microsoft DotNet Framework (ref Microsoft ADO.NET Step By Step by Rebecca M. Riordan)

SQL (Standard Query Language) - An industry-standard language specifically designed to enable people to create databases, add new data to databases, maintain data, and retrieve selected parts of the data. It was originally developed to operate on data in a database thar follow the relational model.(ref SQL FOR DUMMIES 4th edition by Allen G. Taylor)

I wont get into to deep into SQL just some basic stuff.
The basic is "Select * from tablename" This would select everything from x table. If you want to select information from a specific type (ie from Jan 1 2001 or Janet)... "Select * from table where columnname = "Name" (ie Select * from ClientTable where ClientName = "Janet Wise") Depending on type of code you are using you may or may not need a semicolon(;) at the end of your sql statement (ie Select * from ClientTable where ClientName = "Janet Wise";) There are more complex things like inner joins outter joins groupby max count but you can get more info from SqlCourse.com