In order to fully utilize the capabilities of MS Access, one must learn not only learn the Visual Basic (VB) programming language, but should also learn Standard Query Language (SQL). Once a grasp of these two languages have been obtained, MS Access users can begin to build faster and more efficient databases.
One tool that has proved itself very useful to me over the years is querying data from tables or queries using VB and SQL code. A brief introduction to this process is presented in this article. To best understand this process, an example is provided below along with an explanation of its parts.
'*********CODE*********** Dim rstTemp As Recordset Dim strSQL As String Dim routeNum As Integer strSQL = "SELECT [Route], [Main Route PM], [Intersecting Route], [IntBeginPM], [IntEndPM] â€œ strSQL =Â strSQL + â€œFROM Intersections_list WHERE (((CStr([Route])) = """ + cmbRouteQuery + """));" Set rstTemp = CurrentDb.OpenRecordset(strSQL, dbOpenDynaset) If (Not (rstTemp.EOF)) Then rstTemp.MoveFirst routeNum = rstTemp(0) '************************
After the initial variable declarations, the code assigns an SQL statement to the string variable strSQL. This statement directs Access to gather all the data in the Route, Main Route PM, Intersecting Route, IntBeginPM, and IntEndPM fields of the table named Intersections_list. Furthermore, it directs Access to only gather information from these fields where the Route field is equal to a value held in the combo box cmbRouteQuery.
Once the SQL statement has been set, it is passed to the next line of code which executes it. It should be noted that the dbOpenDynaset variable is built into Access and holds an integer value that changes the type of recordset to open. For most general purposes, using dbOpenDynaset will work just fine.
The â€œif statementâ€ in the code example verifies that the recordset just created contains information. If information is present, the code directs Access to move to the first record in the recordset. The code then stores the route in the first record (routeNum = rstTemp(0)) in the variable routeNum to be used for later use.