Chapter 6: Direct Extraction

Chapter 6: Direct Extraction Transcript

Random sampling, as we have seen, is one method of extracting data. This section will look at Direct Extraction.

Direct Extraction involves entering a set of criteria or conditions and all records which meet those conditions are extracted to a new file. For this example, I want to create a new database of Customers who have credit limits of 30,000 dollars or greater.

To start, ensure Customer is the active file and Data is selected in the Properties window. Next, click the Analysis tab and select Direct in the Extract group. This is the Direct Extraction dialog box.

Start by giving a name to your new database. You do that by clicking on the first row where it says Extraction1 and typing in a new name. I’ll call my file Large Credit Limits.

When you tab out of the name field you go to the Criteria field. If you know the exact equation you need to get the filtered records you can go ahead and type it in. Otherwise, use the Equation Editor. The Equation Editor is launched by the button between File Name and Criteria that looks a little like a calculator.

Remember, I’m looking for Customers who have a credit limit of 30,000 dollars or greater than can be expressed by this equation. To generate that equation, you can either start by typing “credit limit” in the equation box, or you can scroll through the Field list and double click it. I prefer typing. As I type a list of potential fields is displayed. Click enter to have IDEA fill in the value for you.

Next, you either type or select the comparison indicator: Greater Than. Then enter the value you are comparing your data to. In this case, 30,000.

You don’t need to add currency indicators, or thousand separators here, just put in the number. In order for IDEA to run the extraction, your equation must be valid. You can use the Equation Editor to validate your equation by clicking the Validate button.

If your equation is correct, you’ll get a message indicating that it is indeed a valid equation. If there is an error, the message box will indicate either a type error or syntax error. Type errors are when there is a data type mismatch, for example, trying to add or subtract numbers which are stored as character data types. Syntax errors are errors in equations; things like missing operators, or an extra bracket. My equation is fine so I’m going to click the Validate and Exit button on the toolbar and return to the Direct Extraction dialog box.

The equation is now visible in the Criteria line. You can keep creating extractions if you wish by clicking into the next available row and entering a new set of criteria. You can have a maximum of 50 extractions run against a database at one time. When you are done, click OK. The new database opens and is the active file.

To close this file, you can click the X in the title tab, you can right-click on the title tab and select close or you can choose to select close all. I’m going to close them all.