How To Create a Connection Programmatically

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This article was previously published under Q176830

Summary

Under some circumstances, you may need to modify the properties of a connection at run time. This article describes each of the properties and the default values of a connection. The sample code illustrates how to create a connection and use the DBSETPROP() function to set the properties of a connection programmatically.

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More information

The following table indicates the data types and default values associated with each of the properties of a connection.

   Property       Connection Designer Label    Data Type   Default Value
   ---------------------------------------------------------------------

   DispLogin        Display Login               Numeric        1
   Asynchronous     Asynchronous Execution      Logical        .F.
   DispWarnings     Display Warnings            Logical        .F.
   BatchMode        Batch Processing            Logical        .T.
   Transactions     Automatic Transactions      Numeric        1
   PacketSize       Packet Size                 Numeric        4096
   Comment                                      Character      ''
   ConnectTimeOut   Connection (sec)            Numeric        15
   IdleTimeOut      Idle (min)                  Numeric        3
   QueryTimeOut     Query (sec)                 Numeric        3
   WaitTime         Wait Time (ms)              Numeric        100

The sample code below creates and modifies the properties of a connection:

Note You must change Username=<username> and PWD=<strong password> to the correct values before you run this code. Make sure that Username has the appropriate permissions to perform this operation on the database.

   *Begin code
   LOCAL lcconnstring, lcconname, lnconnections, lbconnexists
   lcconnstring    =  "'DSN=PUBS;DATABASE=pubs;Username=<username>;PWD=<strong password>;'"
   lcconnname      =   "VFPCONN"
   lnconnections   =   0
   lbconnexists    =   .F.
   IF !FILE('VFPCONN.DBC')
   CLOSE DATA ALL
   CREATE DATABASE VFPCONN
   ELSE
   OPEN DATABASE VFPCONN
   ENDIF
   lnconnections=ADBOBJECTS(CONNECTS,'CONNECTION')
   IF lnconnections>0
   FOR i=1 TO ALEN(CONNECTS,1)
   IF UPPER(CONNECTS[i])=lcconnname
   lbconnexists=.T.
   EXIT
   ENDIF
   NEXT
   ENDIF
   IF !lbconnexists
   CREATE CONNECTION &lcconnname CONNSTRING (lcconnstring)
   ENDIF
   * Set connection properties to custom values.
   =DBSETPROP('VFPCONN','Connection','DispLogin', 3)
   =DBSETPROP('VFPCONN','Connection','Asynchronous', .T.)
   =DBSETPROP('VFPCONN','Connection','DispWarnings', .T.)
   =DBSETPROP('VFPCONN','Connection','BatchMode', .F.)
   =DBSETPROP('VFPCONN','Connection','Transactions', 2)
   =DBSETPROP('VFPCONN','Connection','PacketSize',8192)
   =DBSETPROP('VFPCONN','Connection','Comment', 'Comment Added')
   =DBSETPROP('VFPCONN','Connection','ConnectTimeOut', 10)
   =DBSETPROP('VFPCONN','Connection','IdleTimeOut', 0)
   =DBSETPROP('VFPCONN','Connection','QueryTimeOut', 0)
   =DBSETPROP('VFPCONN','Connection','WaitTime',150)
   MODI CONNECTION VFPCONN
   RETURN
   *End code.

After running the program code, a dialog appears titled "Connection Designer-VPFCONN." Click the Verify Connection button and a message indicating the connection was successful should appear.

NOTE: In order to use the connection, an ODBC Data source matching the Data source name specified in the connection string must exist.

If the ODBC Data source does not exist, the following ODBC error message is returned:

Connectivity error [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified.

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