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DRIDefault Object

后续版本的 Microsoft SQL Server 将删除该功能。请避免在新的开发工作中使用该功能，并着手修改当前还在使用该功能的应用程序。

The DRIDefault object represents the properties of a Microsoft SQL Server column DEFAULT constraint.

显示当前对象的 SQL-DMO 对象模型

注释

The SQL Server column DEFAULT constraint is used to generate data for the column when none is supplied by the user on INSERT statement execution. With the DRIDefault object, you can:

  • Set the DEFAULT constraint for a SQL Server column.

  • Remove the DEFAULT constraint from a SQL Server column.

The Name property of the DRIDefault object uses the SQL Server data type sysname. Name is optional when using the object to create a DEFAULT constraint for a SQL Server column. If Name is not specified, SQL Distributed Management Objects (SQL-DMO) generates an appropriate value.

When setting the Text property of a DRIDefault object, specify only the text for the default. You do not need to build the constraint clause because SQL-DMO does that. The Text property value must evaluate to a constant. For more information about limitations on the Text property, see the description of the DEFAULT constraint in CREATE TABLE (Transact-SQL).

Delimiters that specify constant strings must be present in the Text property value when specifying string data as part of the property. For example, to specify the string "unknown" as the default, use 'unknown'.

To set a DEFAULT constraint on a new SQL Server column

  1. Create a Tableobject.

  2. Create a Column object.

  3. Get the DRIDefault object from the new Columnobject.

  4. Set the Text property of the DRIDefault object to the default for the column.

  5. Add the Column object to the Columns collection of the new Table object.

  6. Add the Table object to the Tables collection of a connected Database object.

To set a DEFAULT constraint on an existing SQL Server column

  1. Get a Table object from the Tables collection of a connected Database object.

  2. Use the BeginAlter method of the Table object to mark the beginning of changes to the SQL Server table.

  3. Get the Column object you want from the Columns collection of the selected Table object.

  4. Get the DRIDefault object from the new Column object.

  5. Set the Text property of the DRIDefault object to the default for the column.

  6. Use the DoAlter method of the Table object to submit changes to the instance of SQL Server.

请参阅

参考

Column Object

Table Object