Exporting data into text files and importing text files into Access Jour 772 & 472 / Chinoy

Transcription

1 Exporting data into text files and importing text files into Access Jour 772 & 472 / Chinoy The materials for the data acquisition assignment include a brief discussion of importing text files into Access: This is useful to you in two ways. First, in the course of your data acquisition assignment, you may encounter agencies that keep their data in some program other than Microsoft Access or Microsoft Excel. If the people with whom you are dealing suggest that this is a problem for you, you will have the knowledge to know what to ask for in order for them to make the data available to you in a format you can import into Access or Excel. Second, you may come across data on the Web that s stored in this format (federal campaign contributions data, for example), and it will not be a mystery to you. Access and Excel can import data from a great many other programs and file formats (though Excel is limited to databases with no more than 65,535 records plus a row for column names). Sometimes Access and Excel can export these records directly. In other cases, the keepers of those databases can export them in either a data file format known as.dbf, or they can export the data into one of two types of text files: comma delimited (there is an example at this link: DamsSample_Delimited_Text.txt ) or fixed length (there is an example here: DamsSample_Fixed_Length_Text.txt ). Those two examples do not include field names. Here s a link to an example of a file that does: DamsSample_Delimited_Text_and_Headers.txt. Access can export data into these formats as well. We ll start with that, and we ll use a file named DameDataDemo.mdb. The file can be downloaded here -- DamsDataDemo.mdb and the documentation for the lone table in that database, DamsSample, is here -- DamsSample_Documentation.doc and looks like this: Documentation for DamsSample table in DamsDataDemo.mdb FIELD TYPE START END WIDTH DESCRIPTION NID_ID TEXT National Inventory of Dams ID DAM_NAME TEXT Dam name YEAR_COMPL NUMBER (Integer) Year built NEAR_CITY TEXT City nearest to dam DIST_CITY NUMBER (Integer) Miles from dam to nearest city The top looks like this:

2 The export process looks like this, starting with the table open and picking File and Export from the menu across the top of the screen: Pick the folder in which you want the exported data to reside: Give the new file a name and select the file type option for Text Files The file designated in the example below will be named DamsSample_Export.txt. Then click on the button next to the file name that says Export All -- You will get the Export Text Wizard. Pick the option that says Fixed Width (another name for fixed-length text data):

3 If you click on Next, the Wizard will walk you through the process of showing were the data is broken into fields, which the Wizard recognizes from the layout of the table:

4 You can check the field breaks, and then click Next. This will bring you to the last step, which should be automatically filled in from the information you provided earlier:

5 Click Finish. You should get a message telling you where the exported file is located, like this: If we then go to have a look, here s what we ll see:

6 If we double click in the file name, it will open in the program called NOTEPAD, which is a viewer for plain text files: IMPORTING TEXT FILES INTO ACCESS: The process outlined above also works in reverse, and it s how you would take data provided to you in a text file and convert it back into an Access database. The first step is to create a new Access database. Let s do that and name it DamsImportDemo.mdb. Once you ve done that, go to the File menu at the upper left of the screen and pick Get External Data and then Import. In the dialog box that comes up, navigate to the folder that has the text file we saved DamsSample_Export.txt making sure to indicate at the bottom next to Files of type: that you are looking for text files. Select this file and then click Import.

7 The Import Text Wizard will come up, and it should recognize that you have fixedlength (or referred to here as fixed-width) text data (if it doesn t you can indicate that).

8 From here, you can give Access instructions in one of two ways on how to import the data. One would be to click on Next and then indicated where the fields break, using your record layout. The other would be to click on the button that says Advanced and specify the dimensions and type of each field. Let s do that. At first, we see something that looks like the following, in which the program has estimated where the breaks between fields might be:

9 Let s go through this and type in the correct information based on the record layout below that we saw earlier: FIELD TYPE START END WIDTH DESCRIPTION NID_ID TEXT National Inventory of Dams ID DAM_NAME TEXT Dam name YEAR_COMPL NUMBER (Integer) Year built NEAR_CITY TEXT City nearest to dam DIST_CITY NUMBER (Integer) Miles from dam to nearest city Here s what it looks like when we fill out the import specifications:

10 Then click on OK. You will get back to the Import Text Wizard. Click Next. You will see that the Wizard has now placed the dividing line between fields in the places you indicated:

11 Click Next and stick with the default choice to put the imported data in a new table:

12 Click Next again. Once more, you will see that the Wizard had given the fields the proper names based on the record layout you used earlier: Another screen will appear asking you if you want to add a primary key. For now, just click No primary key.

13 Then click Next. Another screen will appear asking you what you want to name the new table. Let s call it DamsSample_Import:

14 Now click Finish. If all is well, you will get a message that says this: Click OK, and now we ll see our new table listed: You can double-click on it to see the table. Presto! There it is. The text data file has been turned into an Access table:

15 There are a variety of ways that text data can appear and a variety of issues that you can run into when importing text data, but this will give you an idea of the process.