Exporting data into text files and importing text files into Access 2007 Jour 772 & 472 / Chinoy

Transcription

1 Exporting data into text files and importing text files into Access 2007 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, either directly or after those other files have been converted into one of several common file formats for data transfer. Among the most useful is the format known as.dbf. If that is not available, there are two other useful formats in which data is first converted into a text file. One is comma delimited text. The file DamsSample_Delimited_Text.txt is an example. The second is fixed length text. DamsSample_Fixed_Length_Text.txt is an example of that. Those two examples do not include field names within the file, but text files may also come that way, and DamsSample_Delimited_Text_and_Headers.txt is an example. Download these three files to your H drive so that we will have access to them during this exercise. Access can export data into these formats as well. We ll start with that, and we ll use a file you will need to download: DamsDataDemo.mdb. Here s the record layout for the sole table in that file: 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 starts with the table open. Find the External Data tab and from the Export group of icons click on Text File. You will get a dialog box that will prompt you for the location to place the file you are exporting and the name you want to give it. Make sure that the name ends with.txt as you see below and do not check the box asking you whether you want to preserve the formatting. Here we have placed it in the H:\ directory and used the name DamsSample.txt. Click on OK and in the next box, leave the default settings as you find them. We will be exporting the data as comma-delimited text that is, as a text file with the fields separated by commas, the text fields signified by quotation marks, and a carriage return or new line for each record:

3 Click on Next. Again, leave the defaults as you find them: Click on Next again, and we will get a message that we are done: You will see on the same screen that there is an Advanced button. We will not use it now, but if you have a look, you can see that it gives us some options to deal with various types of data we might encounter. Click Finish. You re done exporting. Use Windows Explorer to locate the text file: If you double click in the file name, it will open in the program called NOTEPAD, which is a viewer for plain text files. Here s what the top looks like.

4 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. Open Access and from the Office Button select New. You will then have a choice to name the file and indicate where you would like it to be stored. We will name this one DamsImportDemo.accdb. The.accdb file extension is the file type for databases in the newest version of Access and cannot be read by earlier versions. When you click on Create, Access assumes you want to build a new table called Table1. We don t want to do this, so we will delete this table. This is done by simply closing it without adding any fields or records, as shown by clicking on the button shown below: From the External Data tab, find the Import group and click on Text File: In the dialog box that comes up, navigate to the folder that has the three text files we downloaded earlier from the class Web site to our H drive: DamsSample_Delimited_Text.txt DamsSample_Delimited_Text_and_Headers.txt DamsSample_Fixed_Length_Text.txt We ll import each in turn to get a sense of the process and differences. Start by picking DamsSample_Delimited_Text.txt: You ll now see that the file appears in the Get External Data Text File box. Leave the other default setting to import the data into a new table:

5 Click OK. You see that Access has examined the file and determined, correctly, that it is a delimited file: Click Next and you ll see that Access has also correctly determined that it is commadelimited and uses quotation marks as a text qualifier that is, to identify text fields. It shows you where the fields will break:

6 Click Next again. You will now have a chance to name the fields using your record layout (from earlier in this tip sheet) and to determine whether or not Access has correctly determined the data type in each field. We are going to make a couple of changes. When you get to renaming Field3 as YEAR_COMPL, change the data type from Long Integer to Integer. And when you get to renaming Field5 as DIST_CITY, change the data type from Text to Integer. Then click Next again. You are given a choice to add a primary key. There is no harm in doing this, and it can be useful to help you get back to the original order of the data if you change the order as you work. It gives each field a unique identifier called ID, starting with 1 and increasing sequentially by 1. We ll choose not to have a primary key added now (select No primary key ), but this may be of use to you in the future. Click Next. You can leave the name Access chooses for your table, or change it: Click Finish. You are given a chance to save these steps in case you want to import a similar file again in the future. For now just click Close. You will see that the table now appears in the Navigation Pane list:

7 And if you double-click on it, you can see the table: (You may notice some missing data in the DIST_CITY field. This reflects what was in the text file we imported) The steps for importing a delimited text field that contains a first row with header information field names are similar to the process we just followed. One difference is that when the import wizard reaches the step of confirming the type of data file you are importing, you should check off the box that says First Row Contains Field Names if it is not checked off automatically. You can try this with the file DamsSample_Delimited_Text_and_Headers.txt The process of importing a fixed-length text file one in which fields appear as specified lengths rather than being set off by commas and quotation marks is also similar. You can try it with the file DamsSample_Fixed_Length_Text.txt. Some of the differences: (1). The import wizard should recognize that you are importing fixed-length text:

8 (2). The wizard will make an attempt to suggest where the fields divide... but you may have to adjust this by hand (as would be the case here, where there is an extra field divider that isn t correct). One way is to remove or move the dividing lines with your mouse (instructions are given in t he wizard). The other way is to click on the Advanced button and type in or correct the specifications by hand. In this case, the end result would look like this:

9 The rest of the steps to finish this import will be familiar. You may encounter a variety of issues over time if you make a habit of acquiring and importing data, but this demonstration should demystify the process a bit. If you run into problems in the future, the Access help system click on the right side of the ribbon to reach it should help you troubleshoot common problems. You may also be able to get help from the provider of the data, another experienced user, or NICAR (