Databases Reference
In-Depth Information
Reading table files
The third type of data source you will find consists of the most common table files,
such as Excel, CSV, TXT, XML, or even HTML. For these types of data sources,
the one requirement would be that their content is in a readable, understandable
structure. It will be easier to extract data from them if they are constructed in
the form of a traditional table, that is, only rows and columns (like any table in a
database). However, sometimes these files could contain extra information that is not
actually part of the core table (such as headers or footers) and, therefore, additional
transformations via script are required.
In
Chapter 9
,
Basic Data Transformation
, we will talk about
some techniques for dealing with unstructured table files.
The ability to read table files is especially useful when we want to mix information
from the DBMS and data generated by the business user that might not be stored in
a database. For instance, budget forecasts, external market indicators, and so on.
Extracting data—two hands-on examples
In this section, we will go through the steps required to extract data into a QlikView
document. The extraction process through which we pull data into the QlikView
document consists of:
1.
Connecting to the database
2.
Querying the database
3.
Reloading the QlikView script
We will provide two examples of data extraction using two different data sources:
• A Microsoft Access database
• A table file
