About UDDTs
You should create UDDTs when multiple tables contain columns that share the same type of data, including the length and ability to allow nulls.
Tip:You can change how objects display in the Object Explorer. For example, you can create custom categories or move objects out of existing categories (such as Programmability and Security) in Tools | Options | Explorer | Objects. See Object Options for more information.
User-Defined Data Type Details
You can display details about a UDDT by selecting it in the Object Explorer. The following describes the details associated with each UDDT:
| Use this tab... | To display... |
|---|---|
|
Properties |
Characteristics of the data type such as assigned defaults and rules. |
|
Dependencies |
The objects that contain reference to the UDDT. |
|
Extended Properties |
Extended properties you define to store additional metadata for this object. |
|
Script |
SQL statements for the selected object. |
Create and Alter UDDTs
Note: This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.
To create or alter a user-defined data type
- Select the UDDTs node under the Programmability node in the Object Explorer.
- Select one of the following:
- Click
to create a data type.
- Select a data type and click
to create a data type like the selected one.
- Select a data type and click
to alter it.
- Click
-
Complete the fields as necessary. Review the following for additional information:
General
Description Base Type
Select the data type to use as a base type.
Length /
PrecisionSpecify the length or precision of the data type. This value is automatically calculated based on the data type you select.
Not Null
Select True to allow Null values for this data type or select False if you do not want to allow Null values.
Binding
Description Default
Select the default that you want to bind to any columns that use this data type.
Default Future Only
Select True if you want to check existing values in the column against the default value. If this checkbox is cleared, existing values are not checked.
Rule
Select the rule that you want to bind to any columns that use this data type.
Rule Future Only
Select True if you want to bind the rule to new data types instead of existing data types. If this checkbox is cleared, new and existing data types are bound to the rule.
Rules
Create and Alter Rules
To create or alter a rule
-
Select the Rules node under the Programmability node in the Object Explorer.
- Select one of the following:
- Click
to create a rule.
- Select a rule and click
to create a rule like the selected one.
- Select a rule and click
to alter it.
- Click
-
Complete the fields as necessary. Specify the rule body. Enter the text for this rule using constants, expressions, or variables.
- Complete the remaining pages. See Bind Rules to Columns for more information. See Bind Rules to UDDTs for more information.