SqlExpression Element for ComputedField (ADF)
Specifies a valid Transact-SQL expression that computes the field value.
语法
<NotificationClasses>
<NotificationClass>
...
<Schema>
...
<ComputedFields>
<ComputedField>
...
<SqlExpression>
Element Characteristics
| Characteristic | Description |
|---|---|
Data type |
string, between 0 and 4,000 characters in length. |
Default value |
None. |
Occurrence |
Required once per ComputedField element. |
Updates |
Can be modified, but not added or deleted, when updating the application. |
Element Relationships
| Relationship | Elements |
|---|---|
Parent element |
|
Child elements |
None. |
备注
A Transact-SQL expression is a combination of identifiers, values, and operators that the database engine can evaluate to get a result. You can use any expression that can be part of a SELECT statement. The terms of the expression can be any of the following:
- Constants.
- Calls to functions.
- The notification fields defined in the ADF (but not computed fields).
- The following built-in notification fields:
- SubscriberId
- DeviceName
- DeviceTypeName
- DeviceAddress
- SubscriberLocale
- DeliveryChannelName
For more information, see 表达式（数据库引擎）.
If you update a SqlExpression element, updating the application deletes and re-creates the notification class to which it corresponds. This includes dropping and re-creating the Microsoft SQL Server tables used by this notification class. Any data existing in the original SQL Server tables is permanently deleted.
示例
The following example shows a populated SqlExpression element. The expression here converts the stock price to the nvarchar data type.
<SqlExpression>
CONVERT(NVARCHAR(10), StockPrice, 1)
</SqlExpression>
请参阅
参考
Application Definition File Reference
其他资源
定义通知架构
CONVERT (Transact-SQL)
表达式（数据库引擎）
更新实例和应用程序