What is the relationship of database to microsoft access

MS Access Create Relationships

what is the relationship of database to microsoft access

A relationship helps you combine data from two different tables. In an Access desktop database, you can create a relationship in the Relationships window. There are three types of relationships in Microsoft Access: it easy to create table relationships before you develop other database objects. A one-to-many relationship connects one record in the parent table to many records in the child table. Set the relationship to connect orders to customers or.

The Relationships window opens and displays any existing relationships.

Microsoft Access Relationship Update Speak Khmer - Database khmer

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.

what is the relationship of database to microsoft access

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.

what is the relationship of database to microsoft access

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. 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.

How to define relationships between tables in an Access database

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.

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.

Guide to table relationships - Access

To enforce referential integrity, you must edit the relationship. See the section Change a table relationship for more information.

what is the relationship of database to microsoft access

If you have not yet defined any relationships in your database, the Show Table dialog box is automatically displayed. To create a relationship between a table and itself, add that table two times.

Create a relationship

Drag the field that you want to relate from one table to the related field in the other table. To drag multiple fields, press Ctrl, click each field, and then drag them.

In most cases, you drag the primary key field this field is displayed in bold text from one table to a similar field this field frequently has the same name that is called the foreign key in the other table. Make sure that the field names that are displayed in the two columns are correct. You can change the names if it is necessary.

what is the relationship of database to microsoft access

Set the relationship options if it is necessary. These options will be explained in detail later in this article. Click Create to create the relationship. Repeat steps 4 through 7 for each pair of tables that you want to relate. Whether you save the layout or do not save the layout, the relationships that you create are saved in the database.

However, referential integrity is not enforced with queries. How to define a many-to-many relationship To create a many-to-many relationship, follow these steps: Create the two tables that will have a many-to-many relationship.

Create a third table. This is the junction table. In the junction table, add new fields that have the same definitions as the primary key fields from each table that you created in step 1. In the junction table, the primary key fields function as foreign keys. You can add other fields to the junction table, just as you can to any other table.

what is the relationship of database to microsoft access

In the junction table, set the primary key to include the primary key fields from the other two tables. Note To create a primary key, follow these steps: Open a table in Design view. Select the field or fields that you want to define as the primary key. To select one field, click the row selector for the desired field. To select multiple fields, hold down the Ctrl key, and then click the row selector for each field.

In Access or in Accessclick Primary Key on the toolbar. Define a one-to-many relationship between each primary table and the junction table. Referential integrity Referential integrity is a system of rules that Access uses to make sure that relationships between records in related tables are valid, and that you do not accidentally delete or change related data.

The matching field from the primary table is a primary key or has a unique index. The related fields have the same data type. There are two exceptions. Both tables belong to the same Access database. If the tables are linked tables, they must be tables in Access format, and you must open the database in which they are stored to set referential integrity.

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 on the field name and select the appropriate field from the list. To enforce referential integrity for this relationship, select the Enforce Referential Integrity box.

When you are finished in the Relationships window, click Save to save your relationship layout changes. Access draws a relationship line between the two tables. If you selected the Enforce Referential Integrity check box, the line appears thicker at each end. This means that 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 that 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. It can have an index, but it must allow duplicates.

When one field has a unique index, and the other does not, Access creates a one-to-many relationship.