Access Tables- Learn How To Use the Relationships Window
Link tables in Access desktop databases by adding joins and creating relationships. A relationship in Access helps you combine data from two different tables. Each relationship consists of fields in two tables, with data that corresponds. Home · Access Tables Learn How To Use the Relationships Window Search MS Office A-Z | Search Web Pages/ Design A-Z.
The Relationships window opens and displays any existing relationships. If no table relationships have been defined and you are opening the Relationships window for the first time, Access prompts you to add a table or query to the window. Open the Relationships window Click File, and then click Open. Select and open the database. On the Database Tools tab, in the Relationships group, click Relationships. If the database contains relationships, the Relationships window appears. If the database does not contain any relationships and you are opening the Relationships window for the first time, the Show Table dialog box appears.
Click Close to close the dialog box. On the Design tab, in the Relationships group, click All Relationships. This displays all of the defined relationships in your database. Note that hidden tables tables for which the Hidden check box in the table's Properties dialog box is selected and their relationships will not be shown unless the Show Hidden Objects check box is selected in the Navigation Options dialog box. A table relationship is represented by a relationship line drawn between tables in the Relationships window.
A relationship that does not enforce referential integrity appears as a thin line between the common fields supporting the relationship. When you select the relationship by clicking its line, the line thickens to indicate it is selected.
If you enforce referential integrity for this relationship, the line appears thicker at each end. When the Relationships window is active, you can select from the following commands on the ribbon: On the Design tab, in the Tools group: When you select a relationship line, you can click Edit Relationships to change the table relationship.
You can also double-click the relationship line.
MS Access One-To-One Relationship
The report shows only the tables and relationships that are not hidden in the Relationships window. On the Design tab, in the Relationships group: Note that hidden tables tables for which the Hidden check box in the table's Properties dialog box is selected and their relationships will not be shown unless Show Hidden Objects is selected in the Navigation Options dialog box. If you made any changes to the layout of the Relationships window, you are asked whether to save those changes.
Top of Page Create a table relationship You can create a table relationship by using the Relationships window, or by dragging a field onto a datasheet from the Field List pane. When you create a relationship between tables, the common fields are not required to have the same names, although it is often the case that they do. Rather, those fields must have the same data type. If the primary key field is an AutoNumber field, however, the foreign key field can be a Number field if the FieldSize property of both fields is the same.
When both common fields are Number fields, they must have the same FieldSize property setting. Create a table relationship by using the Relationships window Click File, and then click Open. If you have not yet defined any relationships, the Show Table dialog box automatically appears. If it does not appear, on the Design tab, in the Relationships group, click Show Table.
The Show Table dialog box displays all of the tables and queries in the database. To see only tables, click Tables. To see only queries, click Queries. To see both tables and queries, click Both. Select one or more tables or queries and then click Add.
When you have finished adding tables and queries to the Relationships window, click Close. Drag a field typically the primary key from one table to the common field the foreign key in the other table. To drag multiple fields, press the CTRL key, click each field, and then drag them. The Edit Relationships dialog box appears. Verify that the field names shown are the common fields for the relationship. If a field name is incorrect, click the field name and select a new field from the list.
To enforce referential integrity for this relationship, select the Enforce Referential Integrity check box. For more information about referential integrity, see the Understanding Referential Integrity and the Enforce Referential Integrity sections. The relationship line is drawn between the two tables.
If you selected the Enforce Referential Integrity check box, the line appears thicker at each end.
This means the Indexed property for these fields should be set to Yes No Duplicates. If both fields have a unique index, Access creates a one-to-one relationship. This means the Indexed property for this field should be set to Yes No Duplicates. The field on the "many" side should not have a unique index.How to create One To One relationship in MS Access _
When one field has a unique index and the other does not, Access creates a one-to-many relationship. Create a table relationship by using the Field List pane You can add a field to an existing table that is open in Datasheet view by dragging it from the Field List pane. The Field List pane shows fields available in related tables and also fields available in other tables.
When you drag a field from an "other" unrelated table and then complete the Lookup Wizard, a new one-to-many relationship is automatically created between the table in the Field List pane and the table to which you dragged the field. This relationship, created by Access, does not enforce referential integrity by default.
To enforce referential integrity, you must edit the relationship.
Guide to table relationships
See the section Change a table relationship for more information. Open a table in Datasheet view On the File tab, click Open. In the Open dialog box, select and open the database. In the Navigation Pane, right-click the table to which you want to add the field and create the relationship, and then click Open.
The Field List pane appears. The Field List pane shows all of the other tables in your database, grouped into categories. When you work with a table in Datasheet view, Access displays fields in either of two categories in the Field List pane: Fields available in related tables and Fields available in other tables.
The first category lists all of the tables that have a relationship with the table you are currently working with. The second category lists all of the tables with which your table does not have a relationship. To add a field to your table, drag the field that you want from the Field List pane to the table in Datasheet view.
Drag the field that you want from the Field List pane to the table that is open in Datasheet view. When the insertion line appears, drop the field in position.
The Lookup Wizard starts. Follow the instructions to complete the Lookup Wizard. The field appears in the table in Datasheet view. When you drag a field from an "other" unrelated table and then complete the Lookup Wizard, a new one-to-many relationship is automatically created between the table in the Field List and the table to which you dragged the field. Top of Page Delete a table relationship To remove a table relationship, you must delete the relationship line in the Relationships window.
Carefully position the cursor so that it points at the relationship line, and then click the line. The relationship line appears thicker when it is selected. Note that when you remove a relationship, you also remove referential integrity support for that relationship, if it is enabled. As a result, Access will no longer automatically prevent the creation of orphan records on the "many" side of a relationship.
Create, edit or delete a relationship
The Relationships window appears. If you have not yet defined any relationships and this is the first time you are opening the Relationships window, the Show Table dialog box appears. If the dialog box appears, click Close. All tables that have relationships are displayed, showing relationship lines.
Click the relationship line for the relationship that you want to delete. Access might display the message Are you sure you want to permanently delete the selected relationship from your database?. If this confirmation message appears, click Yes. Repeat the previous step to add the second table, and so on. Finally click on the Close button to finish adding tables. Now the Relationships window will appear with the tables added before. To create the relationship: Drag the field of the principal table to the equivalent field in the related table.
In our case drag Number in Customers table to Customer in Invoices table. Normally you drag the primary key of the primary table. To relate tables with two or more fields, first select the fields mantaining CTRL key down, and then drag them.
The Edit relationships dialogue box appears next: At the top should be the names of the related tables Customers and Invoices and below this the names of the related fields Number and Customer. Observe at the bottom the Relationship type assigned depends on the charateristics of the related fields in our case One-to-Many Activate the Enforce Referential integrity by clicking on it.
If you want to know more about referential integrity and Cascade procedures clic here.