Lesson 1: Creating the Market Basket Mining Structure

Article
11/15/2012

In this lesson, you will create a mining structure that allows you to predict what Adventure Works Cycles products a customer tends to purchase at the same time. If you are unfamiliar with mining structures and their role in data mining, see Mining Structures (Analysis Services - Data Mining).

The association mining structure that you will create in this lesson supports adding mining models based on the Microsoft Association Algorithm. In later lessons, you will use the mining models to predict the type of products a customer tends to purchase at the same time, which is called a market basket analysis. For example, you may find that customers tend to buy mountain bikes, bike tires, and helmets at the same time.

In this lesson, the mining structure is defined by using nested tables. Nested tables are used because the data domain that will be defined by the structure is contained within two different source tables. For more information on nested tables, see Nested Tables (Analysis Services - Data Mining).

CREATE MINING STRUCTURE Statement

In order to create a mining structure containing a nested table, you use the CREATE MINING STRUCTURE (DMX) statement. The code in the statement can be broken into the following parts:

Naming the structure
Defining the key column
Defining the mining columns
Defining the nested table columns

The following is a generic example of the CREATE MINING STRUCTURE statement:

CREATE MINING STRUCTURE [<Mining Structure Name>]
(
   <key column>,
   <mining structure columns>,
   <table columns>
   (  <nested key column>,
      <nested mining structure columns> )
)

The first line of the code defines the name of the structure:

CREATE MINING STRUCTURE [Mining Structure Name]

For information about naming an object in DMX, see Identifiers (DMX).

The next line of the code defines the key column for the mining structure, which uniquely identifies an entity in the source data:

<key column>

The next line of the code is used to define the mining columns that will be used by the mining models associated with the mining structure:

<mining structure columns>

The next lines of the code define the nested table columns:

<table columns>
(  <nested key column>,
   <nested mining structure columns> )

For information about the types of mining structure columns that you can define, see Mining Structure Columns.

Note

By default, SQL Server Data Tools (SSDT) creates a 30 percent holdout data set for each mining structure; however, when you use DMX to create a mining structure, you must manually add the holdout data set, if desired.

Lesson Tasks

You will perform the following tasks in this lesson:

Create a new blank query
Alter the query to create the mining structure
Execute the query

Creating the Query

The first step is to connect to an instance of Analysis Services and create a new DMX query in SQL Server Management Studio.

To create a new DMX query in SQL Server Management Studio

Open SQL Server Management Studio.
In the Connect to Server dialog box, for Server type, select Analysis Services. In Server name, type LocalHost, or the name of the instance of Analysis Services that you want to connect to for this lesson. Click Connect.
In Object Explorer, right-click the instance of Analysis Services, point to New Query, and then click DMX.

Query Editor opens and contains a new, blank query.

Altering the Query

The next step is to modify the CREATE MINING STRUCTURE statement described above to create the Market Basket mining structure.

To customize the CREATE MINING STRUCTURE statement

In Query Editor, copy the generic example of the CREATE MINING STRUCTURE statement into the blank query.

Replace the following:

[mining structure name]

with:

[Market Basket]

Replace the following:
```
<key column>
```
with:
```
OrderNumber TEXT KEY
```

Replace the following:

<table columns>
(  <nested key column>,
   <nested mining structure columns> )

with:

    [Products] TABLE (
        [Model] TEXT KEY
    )

The TEXT KEY language specifies that the Model column is the key column for the nested table.

The complete mining structure statement should now be as follows:

CREATE MINING STRUCTURE [Market Basket] (
    OrderNumber TEXT KEY,
    [Products] TABLE (
        [Model] TEXT KEY
    )
)

On the File menu, click Save DMXQuery1.dmx As.
In the Save As dialog box, browse to the appropriate folder, and name the file Market Basket Structure.dmx.

Executing the Query

The final step is to execute the query. After a query is created and saved, it needs to be executed (that is, the statement needs to be run) in order to create the mining structure on the server. For more information about executing queries in Query Editor, see Database Engine Query Editor (SQL Server Management Studio).

To execute the query

In Query Editor, on the toolbar, click Execute.

The status of the query is displayed in the Messages tab at the bottom of Query Editor after the statement finishes executing. Messages should display:
```
Executing the query 
Execution complete
```
A new structure named Market Basket now exists on the server.

In the next lesson, you will add mining models to the Market Basket mining structure you just created.

Next Lesson

Lesson 2: Adding Mining Models to the Market Basket Mining Structure

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