Перечисление DataType

Статья
04/26/2013

Indicates the data type of columns in data flow components and the data flow buffer.

Пространство имен: Microsoft.SqlServer.Dts.Runtime.Wrapper
Сборка: Microsoft.SqlServer.DTSRuntimeWrap (в Microsoft.SqlServer.DTSRuntimeWrap.dll)

Синтаксис

'Декларация
Public Enumeration DataType
'Применение
Dim instance As DataType

public enum DataType

public enum class DataType

type DataType

public enum DataType

Элементы

	Имя элемента	Описание
	DT_BOOL	A Boolean value. The numeric value is 11.
	DT_BYREF_BOOL	A pointer to a Boolean value. The numeric value is 16395.
	DT_BYREF_CY	A pointer to a currency value. This data type is an 8-byte value with a scale of 4 and a maximum precision of 19. The numeric value is 16390.
	DT_BYREF_DATE	A pointer to a date structure that consists of year, month, date, and hour. The numeric value is 16391.
	DT_BYREF_DBDATE	A pointer to a date structure that consists of year, month, and date. The numeric value is 16517.
	DT_BYREF_DBTIME	A pointer to a time structure that consists of hour, minute, and second. The numeric value is 16518.
	DT_BYREF_DBTIME2	A pointer to a time structure that consists of hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The numeric value is 16520.
	DT_BYREF_DBTIMESTAMP	A pointer to a timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 3 digits. The numeric value is 16519.
	DT_BYREF_DBTIMESTAMP2	A pointer to a timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The numeric value is 16522.
	DT_BYREF_DBTIMESTAMPOFFSET	A pointer to a timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The DT_DBTIMESTAMPOFFSET data type also has a time zone offset. This offset specifies the number of hours and minutes that the time is offset from the Coordinated Universal Time (UTC). The time zone offset is used by the system to obtain the local time. The numeric value is 16521.
	DT_BYREF_DECIMAL	A pointer to an exact numeric value with a fixed precision and a fixed scale. This data type is a 12-byte value with a separate sign, a scale of 0 to 28, and a maximum precision of 29. The numeric value is 16398.
	DT_BYREF_FILETIME	A pointer to a 64-bit value that represents the number of 100-nanosecond intervals since January 1, 1601. The numeric value is 16448.
	DT_BYREF_GUID	A pointer to a GUID. The numeric value is 16456.
	DT_BYREF_I1	A pointer to a 1-byte, signed integer. The numeric value is 16400.
	DT_BYREF_I2	A pointer to a 2-byte, signed integer. The numeric value is 16386.
	DT_BYREF_I4	A pointer to a 4-byte, signed integer. The numeric value is 16387.
	DT_BYREF_I8	A pointer to an 8-byte, signed integer. The numeric value is 16404.
	DT_BYREF_NUMERIC	A pointer to an exact numeric value with a fixed precision and scale. This data type is a 16-byte value with a separate sign, a scale of 0 to 38, and a maximum precision of 38. The numeric value is 16515.
	DT_BYREF_R4	A pointer to a single-precision floating-point value. The numeric value is 16388.
	DT_BYREF_R8	A pointer to a double-precision floating-point value. The numeric value is 16389.
	DT_BYREF_UI1	A pointer to a 1-byte, unsigned integer. The numeric value is 16401.
	DT_BYREF_UI2	A pointer to a 2-byte, unsigned integer. The numeric value is 16402.
	DT_BYREF_UI4	A pointer to a 4-byte, unsigned integer. The numeric value is 16403.
	DT_BYREF_UI8	A pointer to an 8-byte, unsigned integer. The numeric value is 16405.
	DT_BYTES	A binary data value. The length is variable and the maximum length is 8,000 bytes. The numeric value is 128.
	DT_CY	A currency value. This data type is an 8-byte value with a scale of 4 and a maximum precision of 19. The numeric value is 6.
	DT_DATE	A date structure that consists of year, month, day, and hour. The DT_DATE data type is implemented using an 8-byte floating-point number. Days are represented by whole number increments, starting with 30 December 1899, and midnight as time zero. Hour values are expressed as the absolute value of the fractional part of the number. This means that DT_DATE can represent minutes, seconds, and even milliseconds as well. However, floating point value cannot represent all real values; therefore, there are limits on the range of dates that can be presented in DT_DATE. On the other hand, DT_DBTIMESTAMP is represented by a structure that has individual fields for year, month, day, hours, minutes, seconds, and milliseconds, and this data type has no limits on ranges of the dates it can present. The numeric value is 7.
	DT_DBDATE	A date structure that consists of year, month, and date. The numeric value is 133.
	DT_DBTIME	A time structure that consists of hour, minute, and second. The numeric value is 134.
	DT_DBTIME2	A time structure that consists of hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The numeric value is 145.
	DT_DBTIMESTAMP	A timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 3 digits. The numeric value is 135.
	DT_DBTIMESTAMP2	A timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The numeric value is 304.
	DT_DBTIMESTAMPOFFSET	A timestamp structure that consists of year, month, day, hour, minute, second, and fractional seconds. The fractional seconds have a maximum scale of 7 digits. The DT_DBTIMESTAMPOFFSET data type also has a time zone offset. This offset specifies the number of hours and minutes that the time is offset from the Coordinated Universal Time (UTC). The time zone offset is used by the system to obtain the local time. The numeric value is 146.
	DT_DECIMAL	An exact numeric value with a fixed precision and a fixed scale. This data type is a 12-byte value with a separate sign, a scale of 0 to 28, and a maximum precision of 29. The numeric value is 14.
	DT_EMPTY	A data type that does not have a value. The numeric value is 0.
	DT_FILETIME	A 64-bit value that represents the number of 100-nanosecond intervals since January 1, 1601. The numeric value is 64.
	DT_GUID	A globally unique identifier (GUID). The numeric value is 72.
	DT_I1	A 1-byte, signed integer. The numeric value is 16.
	DT_I2	A 2-byte, signed integer. The numeric value is 2.
	DT_I4	A 4-byte, signed integer. The numeric value is 3.
	DT_I8	An 8-byte, signed integer. The numeric value is 20.
	DT_IMAGE	A binary value with a maximum size of 231–1 (2,147,483,647) bytes. The numeric value is 301.
	DT_NTEXT	A Unicode character string with a maximum length of 2^30–1 (1,073,741,823) characters. The numeric value is 303.
	DT_NULL	A data type with a value of NULL. The numeric value is 1.
	DT_NUMERIC	An exact numeric value with a fixed precision and scale. This data type is a 16-byte value with a separate sign, a scale of 0 to 38, and a maximum precision of 38. The numeric value is 131.
	DT_R4	A single-precision floating-point value. The numeric value is 4.
	DT_R8	A double-precision floating-point value. The numeric value is 5.
	DT_STR	A null-terminated ANSI/MBCS character string. The numeric value is 129.
	DT_TEXT	An ANSI/MBCS character string with a maximum length of 231–1 (2,147,483,647) characters. The numeric value is 302.
	DT_UI1	A 1-byte, unsigned integer. The numeric value is 17.
	DT_UI2	A 2-byte, unsigned integer. The numeric value is 18.
	DT_UI4	A 4-byte, unsigned integer. The numeric value is 19.
	DT_UI8	An 8-byte, unsigned integer. The numeric value is 21.
	DT_WSTR	A null-terminated Unicode character string. The numeric value is 130.

Замечания

Data types are divided into reference types and value types. Reference types point to an object of the specified type. Value types contain the actual data, not a pointer to the data.

For those data types that are value types, there are times where you need a pointer to their data, not the data itself. In the member table, the DT_BYREF* members are fields that were created to be pointers to value types.

For more information, see Работа с типами данных в потоке данных.

Примечание
Boolean values are logical values, not numbers. Although Boolean values may be displayed as numbers in some environments, they are not stored as numbers, and various programming languages represent Boolean values as numeric values differently, as do the .NET Framework methods. For example, the conversion functions available in Visual Basic convert True to -1; however, the System.Convert.ToInt32 method in the .NET Framework converts True to +1. The Службы Integration Services Expression Language converts True to -1. To avoid errors or unexpected results, you should not write code that relies on particular numeric values for True and False. Wherever possible, you should restrict usage of Boolean variables to the logical values for which they are designed.

Boolean values are logical values, not numbers. Although Boolean values may be displayed as numbers in some environments, they are not stored as numbers, and various programming languages represent Boolean values as numeric values differently, as do the .NET Framework methods.

For example, the conversion functions available in Visual Basic convert True to -1; however, the System.Convert.ToInt32 method in the .NET Framework converts True to +1. The Службы Integration Services Expression Language converts True to -1.

To avoid errors or unexpected results, you should not write code that relies on particular numeric values for True and False. Wherever possible, you should restrict usage of Boolean variables to the logical values for which they are designed.

For more information about data types, see Типы данных служб Integration Services.

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Пространство имен Microsoft.SqlServer.Dts.Runtime.Wrapper

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