CDaoQueryDefInfo Structure

The CDaoQueryDefInfo structure has the following form:

struct CDaoQueryDefInfo
{
   CString m_strName;               // Primary
   short m_nType;                   // Primary
   COleDateTime m_dateCreated;      // Secondary
   COleDateTime m_dateLastUpdated;  // Secondary
   BOOL m_bUpdatable;               // Secondary
   BOOL m_bReturnsRecords;          // Secondary
   CString m_strSQL;                // All
   CString m_strConnect;            // All
   short m_nODBCTimeout;            // All
};

The CDaoQueryDefInfo structure contains information about a querydef object defined for data access objects (DAO). The querydef is an object of class CDaoQueryDef. The references to Primary, Secondary, and All above indicate how the information is returned by the GetQueryDefInfo member function in class CDaoDatabase.

Members

m_strName

Uniquely names the querydef object. For more information, see the topic "Name Property" in DAO Help. Call CDaoQueryDef::GetName to retrieve this property directly.

m_nType

A value that indicates the operational type of a querydef object. The value can be one of the following:

• dbQSelect   Select — the query selects records.
  
  
• dbQAction   Action — the query moves or changes data but does not return records.
  
  
• dbQCrosstab   Crosstab — the query returns data in a spreadsheet-like format.
  
  
• dbQDelete   Delete — the query deletes a set of specified rows.
  
  
• dbQUpdate   Update — the query changes a set of records.
  
  
• dbQAppend   Append — the query adds new records to the end of a table or query.
  
  
• dbQMakeTable   Make-table — the query creates a new table from a recordset.
  
  
• dbQDDL   Data-definition — the query affects the structure of tables or their parts.
  
  
• dbQSQLPassThrough   Pass-through — the SQL statement is passed directly to the database backend, without intermediate processing.
  
  
• dbQSetOperation   Union — the query creates a snapshot-type recordset object containing data from all specified records in two or more tables with any duplicate records removed. To include the duplicates, add the keyword ALL in the querydef’s SQL statement.
  
  
• dbQSPTBulk   Used with dbQSQLPassThrough to specify a query that does not return records.

  Note   To create an SQL pass-through query, you do not set the dbQSQLPassThrough constant. This is set automatically by the Microsoft Jet database engine when you create a querydef object and set the Connect property.

  For more information, see the topic "Type Property" in DAO Help.

m_dateCreated

The date and time the querydef was created. To directly retrieve the date the querydef was created, call the GetDateCreated member function of the CDaoTableDef object associated with the table. See Comments below for more information. Also see the topic "DateCreated, LastUpdated Properties" in DAO Help.

m_dateLastUpdated

The date and time of the most recent change made to the querydef. To directly retrieve the date the table was last updated, call the GetDateLastUpdated member function of the querydef. See Comments below for more information. And see the topic "DateCreated, LastUpdated Properties" in DAO Help.

m_bUpdatable

Indicates whether changes can be made to a querydef object. If this property is TRUE, the querydef is updatable; otherwise, it is not. Updatable means the querydef object’s query definition can be changed. The Updatable property of a querydef object is set to TRUE if the query definition can be updated, even if the resulting recordset is not updatable. To retrieve this property directly, call the querydef’s CanUpdate member function. For more information, see the topic "Updatable Property" in DAO Help.

m_bReturnsRecords

Indicates whether an SQL pass-through query to an external database returns records. If this property is TRUE, the query returns records. To directly retrieve this property, call CDaoQueryDef::GetReturnsRecords. Not all SQL pass-through queries to external databases return records. For example, an SQL UPDATE statement updates records without returning records, while an SQL SELECT statement does return records. For more information, see the topic "ReturnsRecords Property" in DAO Help.

m_strSQL

The SQL statement that defines the query executed by a querydef object. The SQL property contains the SQL statement that determines how records are selected, grouped, and ordered when you execute the query. You can use the query to select records to include in a dynaset- or snapshot-type recordset object. You can also define bulk queries to modify data without returning records. You can retrieve the value of this property directly by calling the querydef’s GetSQL member function. For more information, see the article DAO Queries in Visual C++ Programmer’s Guide and the topic "SQL Property" in DAO Help.

m_strConnect

Provides information about the source of a database used in a pass-through query. This information takes the form of a connect string. For more information about connect strings, and for information about retrieving the value of this property directly, see the CDaoDatabase::GetConnect member function.

m_nODBCTimeout

The number of seconds the Microsoft Jet database engine waits before a timeout error occurs when a query is run on an ODBC database. When you’re using an ODBC database, such as Microsoft SQL Server, there may be delays because of network traffic or heavy use of the ODBC server. Rather than waiting indefinitely, you can specify how long the Microsoft Jet engine waits before it produces an error. The default timeout value is 60 seconds. You can retrieve the value of this property directly by calling the querydef’s GetODBCTimeout member function. For more information, see the topic "ODBCTimeout Property" in DAO Help.

Comments

Information retrieved by the CDaoDatabase::GetQueryDefInfo member function is stored in a CDaoQueryDefInfo structure. Call GetQueryDefInfo for the database object in whose QueryDefs collection the querydef object is stored. CDaoQueryDefInfo also defines a Dump member function in debug builds. You can use Dump to dump the contents of a CDaoQueryDefInfo object. Class CDaoDatabase also supplies member functions for directly accessing all of the properties returned in a CDaoQueryDefInfo object, so you will probably seldom need to call GetQueryDefInfo.

When you append a new field or parameter object to the Fields or Parameters collection of a querydef object, an exception is thrown if the underlying database does not support the data type specified for the new object.

The date and time settings are derived from the computer on which the querydef was created or last updated. In a multiuser environment, users should get these settings directly from the file server using the net time command to avoid discrepancies in the DateCreated and LastUpdated property settings. For information on using this and other MFC DAO Info structures, see the article DAO Collections: Obtaining Information About DAO Objects in Visual C++ Programmer's Guide.

See Also   CDaoQueryDef, CDaoDatabase