VBA code for creating MS Access Relations - CodeProject
To define table relationships in Access, go to DATABASE TOOLS Tab and click on What we are doing here is creating a one-to-many relationship between the . Only for questions that pertain to Access and Excel, or Access only. I am trying to create a relation between two tables but I am having If I create the relationship manually it works fine but I need to be able to do this via vba. VBA code for easily creating MS Access Relations.; Author: sazakir; Updated: 11 Jun how to create relationships in MS Access using a VBA macro. Especially when you have a lot of tables and Relations between them.
Left Join Between Tables Here is an example of a query with a left join and the results. No Joins Between Tables Queries with multiple tables do not even require a line between the tables. If no lines are specified, a record by record link is assumed. That is every record in the first table is linked to every record in the second table. This is most useful when one of the tables only has one record. Finally, tables may be linked through an expression that establishes a partial match or match based on a range of values.
Examples are shown later. Basing Queries on Other Queries So far, the queries presented are only based on tables. However, Microsoft Access lets you also base queries on other queries. This ability to filter and analyze data across several levels is extremely powerful. The queries themselves behave identically whether the data comes from tables or queries.
Basing queries on other queries can also simplify maintenance of your database by letting you create standard queries that other queries can use. This can be particularly useful in reports.
Of course, you need to be careful modifying the "core" queries. Additionally, when generating reports in multi-user databases, make sure you don't use queries when you should be using temporary tables generated by Make Table and Append queries.
Queries always retrieve the most current data. If you are printing many reports while others are modifying the data, and consistency between reports is important the numbers need to tieyou must create temporary tables with the data you need prior to printing.
You can then base your queries on those "static" tables. Percent of Total For a field, calculating the percent of each record to the total for an entire table is useful for determining the relative size of each group. This can be achieved by creating a summary query and using that in another query with the original table.
In this example, we use the Fortune table containing sales and profits data for large corporations; and two queries "Fortune Totals" and "Fortune PercentOfTotals". Here's how they work: Create a Query calculating the Totals This is a simple query that sums the values in the two fields: For clarity, the resulting fields are named [TotalSales] and [TotalProfits].
Create a Query with the Totals and the Original Table This is a simple select query that retrieves fields from the Fortune table and creates new fields for the Percent of Total calculations.
Notice the two tables are not linked with lines between them. They only interact in the Percent of Total calculations where the values in the calculated fields using TotalSales and TotalProfits as divisors: Run the Query Running the query provides the desired results: Percent of Total in Microsoft Access Reports Calculating percent of total in Microsoft Access reports is even simpler because queries don't need to be created.
The first step is to create a control with the summary total. The value can be the total for the entire report or just the group. Give the text box control a name e.
Create, edit or delete a relationship
You can then reference that control for the value of the total. Frequency Distributions Frequency distributions reveal the number of records that contain values within numeric ranges. By using the VBA function, Partition, you can group on that for intervals of identical widths. In this example, we show how you can define your own groupings of different size ranges, give them your own label and sort the results in the order you expect.
All without writing any code! A simple two table query calculates these results even when the size of the numeric ranges are not identical. In this example, we use two tables Age Groups and Patientsand one query Frequency: Just follow these simple steps: Create a table defining the groups and numeric ranges Simply create a table with four fields: For each record, define the groups and its low and high values: Notice how the [Maximum] value of one record is smaller than the [Minimum] value of the next record.
They cannot be identical or else such values would fall into two groups. In our example, the Age data are integers so using integers in this table is okay. Otherwise, you can use numbers very close to each other e.
You can name and specify as many groups as you like. Create multi-table Select query Create a Totals Select query with the data table and the Group definition table defined above: Notice that the two tables boxes are not linked to each other. The first and third fields in the query come from the group table: The second field is the count of the Patient data table's [ID] field this field is used since it is not null for every record.
The final field defines the link between the two tables.
This "bins" the Patient data into the age groups defined by the Group table. If the Group table's [Group ID] field is not used in the query, the results would be shown in Ascending order by [Group Name] "Under 25" would be the last record. Union Queries Sometimes you may want to show the results of multiple select queries as one.
While we would normally suggest using a temporary table to store results from multiple queries just for clarity and maintainability, there are situations where that's excessive. For instance, some combo boxes for lookups need to show a blank value when the user is not required to make a selection. Here's a example of how to show a list of states with an initial blank row by combining a dummy record: Rather than showing the value from the Virginia record, it returns blank values for both the State and Name fields.
Open the query "Union Query Blank State" to see this. The Relationships window is not available in an Access web app.
- VBA code for creating MS Access Relations
- Create Relationships in Microsoft Access
To create a relationship in an Access web app, see the steps in Create a relationship. If you have not yet defined any relationships, the Show Table dialog box automatically appears.
Easy steps to make data Relationships work in Excel | INTHEBLACK
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, click Both. Select one or more tables or queries and then click Add. After you have finished adding tables and queries to the Relationships document tab, 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 on the field name and select the appropriate 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 section Enforce Referential Integrity. 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.
Fixing Access Annoyances by Phil Mitchell, Evan Callahan
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. Top of Page Create a table relationship by using the Field List pane to add a field 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 in the database.
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 Edit a relationship for more information. Open a table in Datasheet view In the Navigation Pane, double-click the table.
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 with which you are currently working. 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 into 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. Edit a relationship You change a relationship by selecting it in the Relationships window and then editing it.