ACC2000: Create and Drop Tables and Relationships Using SQL DDL

ID: Q209037

The information in this article applies to:

Microsoft Access 2000

Moderate: Requires basic macro, coding, and interoperability skills.

This article applies only to a Microsoft Access database (.mdb).

SUMMARY

Microsoft Access includes a Data Definition Language (DDL) that you can use to create and delete (drop) tables and relationships. You can also do these same operations by using Data Access Objects (DAO) in Visual Basic for Applications. This article describes some of the operations available in DDL.

NOTE: All the examples in this article assume that you add the statements to an Access query and that you run them by clicking Run on the Query menu.

MORE INFORMATION

To use data definition statements, create a new query. Then on the Query menu, point to SQL Specific, and then click Data Definition. Enter your data definition statement in the Data Definition Query window, and then run the query by clicking Run on the Query menu.

To create a table with a PrimaryKey field with an AutoNumber data type and a field called MyText with a Text data type and a length of 10, enter the following statement in the Data Definition Query window, and then run the query.

CREATE TABLE Table1 (Id COUNTER CONSTRAINT PrimaryKey PRIMARY KEY, MyText TEXT (10))

The foreign key side of a relationship does not require a PrimaryKey and can be created by running the following query. This query creates a table with one field with a Long data type and another field with a Text data type with a default size of 255:

CREATE TABLE Table2 (Id LONG, MyText TEXT)

After you create both tables, running the following query creates a one- to-many relationship between Table1 and Table2, with Table1 as the primary side of the relationship:

ALTER TABLE Table2 ADD CONSTRAINT Relation1 FOREIGN KEY ([Id]) REFERENCES Table1 ([Id])

To delete the relationship between the tables, run the following query:

ALTER TABLE Table2 DROP CONSTRAINT Relation1

To delete Table1, run the following query:

DROP TABLE Table1

To delete Table2, run the following query:

DROP TABLE Table2

You can also run DDL statements using the RunSQL action. To run a DDL statement in code, use a procedure similar to the following example:

The sample code in this article uses Microsoft Data Access Objects. For this code to run properly, you need to reference the Microsoft DAO 3.6 Object Library.


Sub ExecuteSQLDDL (SQLString As String)
   Dim db As DAO.Database, qd As DAO.QueryDef
   Set db = DBEngine.Workspaces(0).Databases(0)
   Set qd = db.CreateQueryDef("")
   qd.SQL = SQLString
   qd.Execute
   db.Close
End Sub

To call this Sub procedure, use the following syntax:

ExecuteSQLDDL "DROP TABLE Table1"

REFERENCES

For more information about DDL queries, click Microsoft Access Help on the Help menu, type "data-definition queries" in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

Additional query words:


Keywords          : kbusage kbdta QrySqldd 
Version           : WINDOWS:2000
Platform          : WINDOWS 
Issue type        : kbinfo

Last Reviewed: May 13, 1999