最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
Parameter object ¶
ADO Parameter object provides information about a single parameter thatis used in a stored procedure or query.
Parameter object is added to the Parameters gather around. Parameters set with a specific Command object associated with Command object uses this collection to pass parameters inside and outside stored procedures and queries.
Parameters are used to create parameterized commands. These commands (after they have been defined and stored) use parameters to change some of the details of the command before it is executed. For example, SQL SELECT statement can be defined using parameters WHERE clause, while another parameter is used to define SORT BY the name of the column of the clause.
There are four types of parameters: input parameters, output parameters, input/output parameters and return parameters.Grammar ¶
objectname.property objectname.method
Attribute ¶
Attribute | Description |
|---|---|
Attributes | Sets or returns the properties of a Parameter object. |
Direction | Sets or returns how a parameter is passed to or back from the stored procedure. |
Name | Sets or returns the name of a Parameter object. |
NumericScale | Sets or returns the number to the right of the decimal point of the numeric value of a Parameter object. |
Precision | Sets or returns the maximum number of numbers allowed when representing a numeric value in a parameter. |
Size | Sets or returns the maximum size, in bytes or characters, of the value in the Parameter object. |
Type | Sets or returns the type of a Parameter object. |
Value | Sets or returns the value of a Parameter object. |
Method ¶
Method | Description |
|---|---|
AppendChunk | Appends long binary or character data to a Parameter object. |
Delete | Removes an object from the Parameters collection. |