CDaoTableDefInfo Structure

Статья
10/16/2008

The CDaoTableDefInfo structure contains information about a tabledef object defined for data access objects (DAO).

struct CDaoTableDefInfo
{
   CString m_strName;               // Primary
   BOOL m_bUpdatable;               // Primary
   long m_lAttributes;              // Primary
   COleDateTime m_dateCreated;      // Secondary
   COleDateTime m_dateLastUpdated;  // Secondary
   CString m_strSrcTableName;       // Secondary
   CString m_strConnect;            // Secondary
   CString m_strValidationRule;     // All
   CString m_strValidationText;     // All
   long m_lRecordCount;             // All
};

Параметры

m_strName
Uniquely names the tabledef object. To retrieve the value of this property directly, call the tabledef object's GetName member function. For more information, see the topic "Name Property" in DAO Help.
m_bUpdatable
Indicates whether changes can be made to the table. The quick way to determine whether a table is updatable is to open a CDaoTableDef object for the table and call the object's CanUpdate member function. CanUpdate always returns nonzero (TRUE) for a newly created tabledef object and 0 (FALSE) for an attached tabledef object. A new tabledef object can be appended only to a database for which the current user has write permission. If the table contains only nonupdatable fields, CanUpdate returns 0. When one or more fields are updatable, CanUpdate returns nonzero. You can edit only the updatable fields. For more information, see the topic "Updatable Property" in DAO Help.
m_lAttributes
Specifies characteristics of the table represented by the tabledef object. To retrieve the current attributes of a tabledef, call its GetAttributes member function. The value returned can be a combination of these long constants (using the bitwise-OR (|) operator):
- dbAttachExclusive For databases that use the Microsoft Jet database engine, indicates the table is an attached table opened for exclusive use.
- dbAttachSavePWD For databases that use the Microsoft Jet database engine, indicates that the user ID and password for the attached table are saved with the connection information.
- dbSystemObject Indicates the table is a system table provided by the Microsoft Jet database engine. (Read-only.)
- dbHiddenObject Indicates the table is a hidden table provided by the Microsoft Jet database engine (for temporary use). (Read-only.)
- dbAttachedTable Indicates the table is an attached table from a non-ODBC database, such as a Paradox database.
- dbAttachedODBC Indicates the table is an attached table from an ODBC database, such as Microsoft SQL Server.
m_dateCreated
The date and time the table was created. To directly retrieve the date the table was created, call the GetDateCreated member function of the CDaoTableDef object associated with the table. See Comments below for more information. For related information, see the topic "DateCreated, LastUpdated Properties" in DAO Help.
m_dateLastUpdated
The date and time of the most recent change made to the design of the table. To directly retrieve the date the table was last updated, call the GetDateLastUpdated member function of the CDaoTableDef object associated with the table. See Comments below for more information. For related information, see the topic "DateCreated, LastUpdated Properties" in DAO Help.
m_strSrcTableName
Specifies the name of an attached table if any. To directly retrieve the source table name, call the GetSourceTableName member function of the CDaoTableDef object associated with the table.
m_strConnect
Provides information about the source of an open database. You can check this property by calling the GetConnect member function of your CDaoTableDef object. For more information about connect strings, see GetConnect.
m_strValidationRule
A value that validates the data in tabledef fields as they are changed or added to a table. Validation is supported only for databases that use the Microsoft Jet database engine. To directly retrieve the validation rule, call the GetValidationRule member function of the CDaoTableDef object associated with the table. For related information, see the topic "ValidationRule Property" in DAO Help.
m_strValidationText
A value that specifies the text of the message that your application should display if the validation rule specified by the ValidationRule property is not satisfied. For related information, see the topic "ValidationText Property" in DAO Help.
m_lRecordCount
The number of records accessed in a tabledef object. This property setting is read-only. To directly retrieve the record count, call the GetRecordCount member function of the CDaoTableDef object. The documentation for GetRecordCount describes the record count further. Note that retrieving this count can be a time-consuming operation if the table contains many records.

Заметки

The tabledef is an object of class CDaoTableDef. The references to Primary, Secondary, and All above indicate how the information is returned by the GetTableDefInfo member function in class CDaoDatabase.

Information retrieved by the CDaoDatabase::GetTableDefInfo member function is stored in a CDaoTableDefInfo structure. Call the GetTableDefInfo member function of the CDaoDatabase object in whose TableDefs collection the tabledef object is stored. CDaoTableDefInfo also defines a Dump member function in debug builds. You can use Dump to dump the contents of a CDaoTableDefInfo object.

The date and time settings are derived from the computer on which the base table was created or last updated. In a multiuser environment, users should get these settings directly from the file server to avoid discrepancies in the DateCreated and LastUpdated property settings.