Create Foreign Key Relationships | Microsoft Docs
How to create a relationship in SQL Server. Screenshot of a one to many relationship. We'll use SQL to create the Albums table and one relationship. This means that Table A can have one or more records relating to a single record in You create a relation by adding a foreign key column. One-to-One, One-to-Many Table Relationships in SQL Server A link is created between two tables where the primary key of one table is.
Greater than foreign key references are not currently available for columnstore indexes, memory-optimized tables, or Stretch Database. If a foreign key is defined on a CLR user-defined type column, the implementation of the type must support binary ordering. The table opens in Table Designer. From the Table Designer menu, click Relationships. In the Foreign-key Relationships dialog box, click Add. Click the relationship in the Selected Relationship list.
Click Tables and Columns Specification in the grid to the right and click the ellipses In the Tables and Columns dialog box, in the Primary Key drop-down list, choose the table that will be on the primary-key side of the relationship.
In the grid beneath, choose the columns contributing to the table's primary key. In the adjacent grid cell to the left of each column, choose the corresponding foreign-key column of the foreign-key table. Table Designer suggests a name for the relationship. To change this name, edit the contents of the Relationship Name text box. Choose OK to create the relationship. On the Standard bar, click New Query. A many-to-many relationship is indicated by the following icon.
Click the button to open the Define Relationship dialog box to verify the relationship type is many-to-many, and to view which intermediate measure group is used in the relationship. In subsequent sections, you will learn how to set up a many-to-many dimension and test model behaviors. If you would rather review additional information or try tutorials first, see Learn More at the end of this article.
Create a many-to-many dimension A simple many-to-many relationship includes two dimensions having a many-to-many cardinality, an intermediate measure group for storing member associations, and a fact measure group containing measurable data, such as sum of total sales or the balance of a bank account.
Dimensions in a many-to-many relationship might have correspondent tables in the DSV, where each dimension in the model is based on an existing table in a data source. Conversely, the dimensions in your model might derive from fewer or different physical tables in the DSV. Using Sales Reasons and Sales Orders as a case in point, the Adventure Works sample cube demonstrates a many-to-many relationship using dimensions that exist as model-only data structures, without physical counterparts in the DSV.
The Sales Order dimension is based on a fact table, rather than a dimension table, in the underlying data source. The next procedure assumes that you already know which entities participate in the many-to-many relationship.
Create Foreign Key Relationships
See Learn More for further study. To illustrate the steps used to create a many-to-many relationship, this procedure re-creates one of the many-to-many relationships in the Adventure Works sample cube. If you have the source data that is, the Adventure Works sample data warehouse installed on a relational database engine instance, you can follow these steps. Create a Data Source View using the following existing tables: This is a requirement for establishing a link to the intermediate measure group in a subsequent step.
Creating multiple tables and table relationships
Note If the underlying data source does not provide primary and foreign key relationships, you can create the relationships manually in the DSV. The following example confirms that the tables used in this procedure are linked using primary keys. Create a new dimension based on existing table, DimSalesReason.
Accept all of the default values when specifying the source. For attributes, select all.
Table of Contents
Create a second dimension based on existing table, Fact Internet Sales. Although this is a fact table, it contains Sales Order information. We'll use it to build a Sales Order dimension. In Specify Source Information, you will see a warning that indicates a Name column must be specified. Choose SalesOrderNumber as the Name.
On the next page of the wizard, choose the attributes.
In this example, you can select just SalesOrderNumber. Rename the dimension to Dim Sales Orders, so that you have a consistent naming convention for the dimensions.
Right-click Cubes and select New Cube. You are choosing FactInternetSales because it contains the measures you want to use in the cube. You are choosing FactInternetSalesReason because it is the intermediate measure group, providing member association data that relates sales orders to sales reasons. Choose measures for each fact table. To simplify your model, clear all the measures, and then select just Sales Amount and Fact Internet Sales Count at the bottom of the list.
The FactInternetSalesReason only has one measure, so it is selected for you automatically. You do not need this dimension, so you can clear it from the list. Name the cube and click Finish. Recall that the following icon indicates a many-to-many relationship.
You can see that this dialog box is used to specify a many-to-many relationship. If you were adding dimensions that had a regular relationship instead, you would use this dialog box to change it to many-to-many.
Deploy the project to an Analysis Services multidimensional instance. In the next step, you will browse the cube in Excel to verify its behaviors. Testing Many-to-Many When you define a many-to-many relationship in a cube, testing is imperative to ensure queries return expected results. You should test the cube using the client application tool that will be used by end-users.