MS Access - Basic Relationship Error - Stack Overflow
This is cumbersome to detect in large databases, but Total Access Analyzer finds them easily: Container Open Errors; Table Relationship Window Problems. Microsoft Access comprehensive list all Error Numbers and Descriptions. If you want to change or remove the primary key, first delete the relationship in. Jan 24, Microsoft Access can't create the relationship and enforce ones (create relationship at this stage), you may well see import errors that point to.
The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships. They also make a big difference in performance as your database grows.
Fortunately, you can leave the theoretical stuff to the experts; following a few simple rules will suffice for most needs. The essence of data normalization is just this: Some table-design rules to follow: Split up your data by topic. Think of tables as file folders in a filing cabinet. Identify the main topic headings for your data, and create tables for each distinct topic.
Apply the same organizational logic to the information you plan to store in your Access database. For instance, you have a customers table see Figurebut what data should be stored there? Orders, billing addresses, shipping addresses, phone numbers, everything? A customers table in an early stage of design. It has no extraneous topics such as vendor data but is not yet normalized. Note the multiple phone numbers in a single field; this should never be done. Give every item of data its own field.
For example, many customers will have both a cell phone and a land line. This is never a good idea. A normalized customers table. Note that the address and phone numbers have been split into separate fields holding one item of information apiece. Put repeated items into separate tables. If your customer has two or more phone numbers, you should create distinct phone number fields in the customers table. But what if you need to record something that repeats indefinitely, such as customer orders including customer order numbers?
Microsoft Access error creating relationships - Microsoft Community
This clearly indicates that you need to create a separate table just for orders. In a properly designed database, new data adds rows, not fields. Put reusable information into separate tables. Your goal in database design is to avoid entering the same data twice. Not only does this save work, but it avoids data entry errors or discrepancies that will make it difficult to maintain a database.
An example is a product description. This is a sure sign that this information belongs in a separate table Figure This orders table is not yet fully normalized. Note that product information is repeated verbatim in records 2 and 3. This reusable information should be stored in its own table. Normalized orders and products tables. The product descriptions have been replaced with product codes that refer back to the products table.
For instance, if you create a separate table for orders, you need a way to track which orders go with which customers. MSKB is a good, non-technical article on normalization. For a slightly more technical tutorial, check out http: More to the point, what is a key, and what is a primary key, and why should I care?
Setting up correct table relationships is the second half of good database design. Defining relationships between tables is how you pull that related data back together again. Field Names and Data Types Once you have designed your tables, creating them in Access is pretty straightforward. Field names must be unique within a table but can be reused in other tables.
The trickier part is assigning a data type to each field. Unlike with a table in a Word document, for example, with an Access table you must specify what kind of data you intend to put in each field. Because a database knows what kinds of values are in a specific type of field, it can sift, collate, sort, and view different slices of data in myriad ways and can prevent some kinds of data from interacting in certain undesirable ways.Building relationships between tables when both have duplicates
Here are some simple rules to follow when choosing data types: For money, use the Currency data type. Here are some very basic guidelines.
If your numbers are integers i. So make it a Text field. For foreign keys, you must use the data type of the primary key that the foreign key refers to. For example, if the primary key is an AutoNumber, use the Number data type with the Field Size set to Long Integer for the foreign key.
And duplicate records cause all sorts of headaches. 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.
Microsoft Access Error Numbers and Descriptions
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.
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.
Microsoft Access Errors, Suggestions, and Performance Tips
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.
To enforce referential integrity, you must edit the relationship. 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. 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. If either of the tables employed in the table relationship are in use, perhaps by another person or process, or in an open database object such as a formyou will not be able to delete the relationship.
You must first close any open objects that use these tables before you can remove the relationship. Top of Page Change a table relationship You change a table relationship by selecting it in the Relationships window and then editing it. Carefully position the cursor so that it points at the relationship line, and then click the line to select it. With the relationship line selected, double-click it or click Edit Relationships in the Tools group on the Design tab.
Click the relationship line for the relationship that you want to change. Double-click the relationship line. Make your changes, and then click OK. The Edit Relationships dialog box allows you to change a table relationship. Specifically, you can change the tables or queries on either side of the relationship, or the fields on either side.
You can also set the join type, or enforce referential integrity and choose a cascade option. For more information about the join type and how to set it, see the section Set the join type. For more information about how to enforce referential integrity and choose a cascade option, see the section Enforce referential integrity. Set the join type When you define a table relationship, the facts about the relationship inform your query designs.