AlterDataType Method
未來的 Microsoft SQL Server 版本將移除這項功能。請避免在新的開發工作中使用這項功能，並規劃修改目前使用這項功能的應用程式。
The AlterDataType method alters the data type of the referenced column.
語法
object.AlterDataType(Datatype, [ Length ] , [ Precision ] , [ Scale ] )
Parts
object
Expression that evaluates to an object in the Applies To list.DataType
String that specifies the new data type.Length
Optional long integer that specifies the length of a string data type.Precision
Optional long integer that specifies the precision of a numeric data type.Scale
Optional long integer that specifies the scale of a numeric data type.
Prototype (C/C++)
HRESULT AlterDataType(
SQLDMO_LPCSTR DataType,
long Length,
long Precision,
long Scale);
備註
When using AlterDataType to convert the data type of an existing column to a new data type, the two data types must be compatible. For example, an int data type can be converted to a decimal data type, and a char data type can be converted to an nvarchar data type. However string data types cannot be converted to numeric data types.
[!附註]
If an application calls AlterDataType on an instance of SQL Server version 7.0, the constant, SQLDMO_E_SQL80ONLY, and the message "This property or method requires Microsoft SQL Server 2000" are returned.