No mater what you do with dimensions you will almost definitely come across the “Datalink Properties Wizard”, this article shows you how to use it. In this article we are going to connect to the museum database that comes with the Dimensions Development Library. It can be found in the following directory.
C:\Program Files\IBM\SPSS\DataCollection\7\DDL\Data\Data Collection File
When we are presented with the “Datalink Properties Wizard” the first thing we will see is the following screen.
The first thing we need to do is to select the type of Metadata that we are going to use. In this example we are going to connect to the Museum Dimensions Data file ( DDF ), to find the files navigate to the following directory in the DDL
C:\Program Files\IBM\SPSS\DataCollection\7\DDL\Data\Data Collection File
The first thing we need to make sure is that the “Metadata Type” is set to “Dimensions Metadata Document” once this is done we will make the Metadata location point to the MDD that we are going to use. Once we have filled this information in we need to select the “Case Data Type”.
The “Case Data Type” needs to be set to “Dimensions Data File ( Read Write )” when this is selected two things could happen. The first is that the “Case Data Location” field is automatically populated with some text. This will probably happen if you are using the museum data, and is because the mdd file used has stored the connection string to the database in the mdd, ( you can see all the datasources available if you open up the mdd file with MDMExplorer ) , if it does not populate automatically then don’t worry we can fill in the information by clicking the “Browse” button.
Now we could just click ok and away we go, but I would like to explain the two other tabs first before we do that. The first tab is the Advanced tab and this can be used to manipulate how the DSC read the data. This tab is the same for all Data Source Components ( DSC’s ).
So what do all these settings that we have to play with mean
If existing datasource has a different location: As we know, if we have a data file we should also have a mdd file. This option specifies what should happen if there is no DataSource object in the MDM Document with the same case data type. The possible options are,
Default : Use the Data Source (except for location): Select this option if you want to use the first DataSource object of the same type that is encountered and do not want to store the new case data location in it.
Use the Data Source and store the new location: Same as default behaviour except the datasource is stored.
Create a new Data Source: If you have manipulated the metadata in your script you may want to create a new datasource object so that it can be re-used later.
Raise an Error: If we don’t have an MDD raise an error.
Reading categorical data: This option allows us to specify how the data is presented to the user, we have two options that we can use and they are,
Default : Return Category Values: when we use this setting we will see the numerical values that represent the data. An example would be {34}
Return Category Names: When we use this setting we will see the unique id that represents the data. An example of this would be {Very_Good}
Writing data: This option allows us to manage what happens when the case data dsc is used to export data. We have three options and they are,
Default : Append to existing data: If the data file exists, any data exported will be appended to the end of the existing file.
Replace existing data: If the data file exists, any data exported will be replace the existing metadata and data files.
Replace existing data but preserve schema: If the data file exists, any data exported will be replace the existing data file only.
Perform validation: This options allows us to decide if the case data should be validated before it is written.
Allow Dirty Data: If you have chosen to Validate the data, then you need to let the cdsc what to do with records that do not pass the validation. The type of validation is DSC specific and is written into the DSC and cannot be changed.
The second tab is the “All tab” and this gives you access to all the initialised properties that the dsc has.
To edit them just highlight the property and click the edit value box. Depending on what property you select will depend on what you see. To find out all the properties of the dsc that you are using , check the DDL. To find a list of all the available dsc’s do the following.
- Load up the DDL
- Click the contents tab
- Expand the “Dimensions Datamodel” section
- Expland the “Available DSC’s” section
Then you see everything about your chosen dsc.
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