Microsoft OLE DB 2.0 Programmers Reference and Data Access SDK (Microsoft Professional Editions)

2017-07-07 02:10:07

OLE DB Programmer's Reference

Property group: Column

Property set: DBPROPSET_COLUMN

Type: VT_BOOL

Typical R/W: R/W

Description: Is Long

Indicates whether a column can contain a long value.

Value	Meaning
VARIANT_TRUE	The column can contain a long value, and pwszTypeName in the DBCOLUMNDESC structure is not required to be specified. If pwszTypeName is not specified, the provider determines the best underlying type as follows: If wType is a fixed length type, creates a column using the best match provider type for that DBTYPE. If wType is a variable length type, the provider looks at the ulColumnSize, bPrecision, and bScale—as well as DBPROP_COL_FIXEDLENGTH, DBPROP_COL_ISLONG, and any other column properties—to determine the best-fit provider type. Note Some 2.0 providers may not support leaving pwszTypeName unspecified. Also, to ensure a specific type, the consumer must specify that type explicitly. (This is true for all providers.) If pwszTypeName is specified, the provider uses wType, ulColumnSize, bPrecision, and bScale—as well as DBPROP_COL_FIXEDLENGTH, DBPROP_COL_ISLONG, and any other column properties—to verify that the selected pwszTypeName matches the specified values.
VARIANT_FALSE	The column cannot contain a long value.

Value

Meaning

VARIANT_TRUE

The column can contain a long value, and pwszTypeName in the DBCOLUMNDESC structure is not required to be specified.

If pwszTypeName is not specified, the provider determines the best underlying type as follows:

If wType is a fixed length type, creates a column using the best match provider type for that DBTYPE.

If wType is a variable length type, the provider looks at the ulColumnSize, bPrecision, and bScale—as well as DBPROP_COL_FIXEDLENGTH, DBPROP_COL_ISLONG, and any other column properties—to determine the best-fit provider type.

Note Some 2.0 providers may not support leaving pwszTypeName unspecified. Also, to ensure a specific type, the consumer must specify that type explicitly. (This is true for all providers.)

If pwszTypeName is specified, the provider uses wType, ulColumnSize, bPrecision, and bScale—as well as DBPROP_COL_FIXEDLENGTH, DBPROP_COL_ISLONG, and any other column properties—to verify that the selected pwszTypeName matches the specified values.

VARIANT_FALSE

The column cannot contain a long value.

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