microsoft access many to many relationship and two primary keys in junction table - Stack Overflow
A many-to-many relationships in a relational database exists when one record in The junction table has a primary key ID field and two foreign key fields. This is how you would add multiple product to an order with the quantity field solution. 3 days ago Appending multiple tables and maintaining key relationships. I have 5 tables that These are also one to many relationships, so there can be quite a few records involved. Thanks for your Microsoft Access MVP Phoenix, AZ. Microsoft Access / VBA Forums on Bytes. i have create a relationship one-to- many between table(a) and table(b) so as if table(a) has is to say, I would not use the exact same name for multiple fields across different tables.
For example, the Northwind Employees table has an EmployeeID field that lists the identification number of each employee. The same table also includes a ReportsTo field that lists the identification number of the employee's manager.
To display the name of each employee's manager, you use a second copy of the Employees table and join the EmployeeID and ReportsTo fields. For example, suppose you want to compare the unit price data in Northwind's Order Details table with the unit price data in the Products table.
Specifically, you want to see those orders where the unit price of the order differs from the unit price of the product. In this case, you look for records where the [Order Details].
UnitPrice field is not equal to the [Products]. Adding Tables to the Relationships Window If you need to establish a new relationship between two tables, your first order of business is to add the tables to the Relationships window. Here are the steps to follow: Access displays the Show Table dialog box, shown in Figure 3.
Click the table you want to add. Access adds the table to the Relationships window. Repeat steps 2 and 3 to add more tables. Click Close to return to the Relationships window. Joining Tables To create a join between two tables or a self-join between two copies of the same tableuse the mouse to click and drag one of the related fields and drop it on the other.
Create a many-to-many relationship in Access
Here are the specific steps: Add the tables you want to join. Arrange the table boxes so that in each box you can see the fields you want to use for the join. Click and drag the related field from one table and drop it on the related field in the other table.
Access displays the Edit Relationships dialog box, shown in Figure 3. The grid should show the names of the fields in each table that you want to relate. If not, use the drop-down list in one or both cells to click the correct field or fields.
If you want Access to enforce referential integrity rules on this relation, click the Enforce Referential Integrity check box. If you do this, two other check boxes become active: For example, if you change a CompanyID value in the Companies table, all related records in the Contacts table have their CompanyID fields updated automatically.
For example, if you delete a record from the Companies table, all records in the Contacts table that have the same CompanyID as the deleted record are also deleted. To set the type of join, choose Join Type to display the Join Properties dialog box, shown in Figure 3. Here, option 1 corresponds to an inner join, option 2 corresponds to a left-outer join, and option 3 corresponds to a right-outer join. When you've clicked the option you want, click OK to return to the Relationships dialog box.
Access establishes the relationship and displays a join line between the two fields.
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. Create a relationship in an Access web app The Relationships window isn't available in an Access web app. Instead of creating a relationship in an Access web app, you create a lookup field that gets values from a related field in another table. The field that your lookup will use as the source for values must already exist before you create your lookup field.
Open the table where you want to create a new lookup field by double-clicking it in the navigation.
Create a many-to-many relationship in Access
In the above example, click the Employees table. Click in the Field Name column just below the last field in the table and type a name for your new lookup field. In the example, type Region as the field name. In the Data Type column, click the arrow and select Lookup. The Lookup Wizard starts. On the first page of the Lookup Wizard, select I want the lookup field to get values from another table or query.
More options appear in the dialog box. Select the name of the table or query that should provide the values for your lookup.
In the example, select Table: After you select the table, use the Which value do you want to display in your lookup list to select the field that you want to use as a display value for your lookup field. By default, Access selects the first text field it can find in the selected table.
In the example, you would leave the selected field, Title, as the display value. Use the Do you want to sort the items in your lookup list to set the sorting, if you want.
The name of the table in this question varies depending on which table you selected in step 5.