PRB: Connection Busy Message With Remote Views of SQL Server Tables

ID: Q217082


The information in this article applies to:


SYMPTOMS

When attempting to open a Remote View using a shared connection to access SQL Server tables, the following error message may appear:

Connection "connection name" is busy


RESOLUTION

Set the FETCHSIZE property of remote views using shared connections to a value of -1.


OPEN DATABASE MYDATA
=DBSETPROP('MyView','View','FetchSize',-1) 
-or-

OPEN DATABASE MYDATA
USE MyView IN 0
SELECT MyView
=CURSORSETPROP('FetchSize',-1) 
Setting the FetchSize Property of the remote view to -1 causes Visual FoxPro to retrieve the complete result set (within the limits set by the MaxRecords setting).


MORE INFORMATION

The default FetchSize Property value for remote views is 100.

The error message indicates that the shared remote connection is in use by another executing statement. This behavior occurs when multiple remote views have been defined with the following characteristics:

  • Using a shared remote connection to the server.


  • Accessing the same base table(s).


  • The number of records being returned is greater than or equal to the FETCHSIZE property of the view.

  • Steps to Reproduce Behavior

    1. From the Windows Control Panel, open ODBC Data Source Administrator, and add a DSN named MyDSN, using the SQL Server ODBC Driver.


    2. Create a program file named "REMOVIEW.PRG" using the following code: (NOTE: This program will create a new SQL Server table in the database that the DSN specifies as the default, and necessitates appropriate permissions.)
      
      lcsafestat=SET('SAFETY')
      lcexclstat=SET('EXCLUSIVE')
      lcMultiLocks=SET('MULTILOCKS')
      SET SAFETY OFF
      SET EXCLUSIVE ON
      SET MULTILOCKS ON
      gnConnHandle=SQLCONNECT('MyDSN','sa','')
      lnCreate=0
      lnUseDB=0
      IF gnConnHandle > 0
         * Use the SQL Server PUBS database
         SQLCommand="USE PUBS"
         lnUseDB=sqlexec(gnConnHandle,SQLCommand)
         IF lnUseDB > 0
            * Create table TEST_A in the PUBS database
            SQLCommand="CREATE TABLE TEST_A (VAR1 CHAR(10) NULL, " + ;
               "VAR2 VARCHAR(20) NULL)"
            lnCreate=sqlexec(gnConnHandle,SQLCommand)
         ENDIF
         * Disconnect from SQL Server
         =sqldisconn(gnConnHandle)
      ENDIF
      IF lnCreate > 0
         * Create a Visual FoxPro database named TESTA
         CREATE DATABASE testa
         * Create a remote connection to SQL Server
         CREATE CONNECTION test1 DATASOURCE 'MyDSN' USERID 'SA' PASSWORD '' ;
            DATABASE 'PUBS'
         * Create three remote views to SQL Server
         IF lnUseDB > 0
            CREATE SQL VIEW testa REMOTE CONNECTION test1 SHARE ;
               AS SELECT * FROM dbo.test_a test_a
            CREATE SQL VIEW testb REMOTE CONNECTION test1 SHARE ;
               AS SELECT * FROM dbo.test_a test_a
            CREATE SQL VIEW testc REMOTE CONNECTION test1 SHARE ;
               AS SELECT * FROM dbo.test_a test_a
         ENDIF
         * Set Properties for the three remote views
         FOR i=1 TO 3
            ViewName="TEST"+CHR(64+i)
            =DBSETPROP(ViewName,'View','UpdateType',1)
            =DBSETPROP(ViewName,'View','WhereType',3)
            =DBSETPROP(ViewName,'View','UseMemoSize',255)
            =DBSETPROP(ViewName,'View','FetchSize',100)
            =DBSETPROP(ViewName,'View','MaxRecords',-1)
            =DBSETPROP(ViewName,'View','Tables','dbo.test_a')
            =DBSETPROP(ViewName,'View','Prepared',.T.)
            =DBSETPROP(ViewName,'View','FetchMemo',.T.)
            =DBSETPROP(ViewName,'View','SendUpdates',.T.)
            =DBSETPROP(ViewName,'View','BatchUpdateCount',1)
            =DBSETPROP(ViewName,'View','CompareMemo',.T.)
            =DBSETPROP(ViewName,'View','FetchAsNeeded',.F.)
            =DBSETPROP(ViewName,'View','ShareConnection',.T.)
         NEXT
         USE testa
         testb=AFIELDS(viewflds)
         FOR i=1 TO ALEN(viewflds,1)
            fld_name=viewflds[i,1]
            viewfield='TESTA'+"."+ALLTRIM(fld_name)
            IF i=1
               =DBSETPROP(viewfield,'Field','KeyField',.T.)
            ELSE
               =DBSETPROP(viewfield,'Field','KeyField',.F.)
            ENDIF
            =DBSETPROP(viewfield,'Field','Updatable',.T.)
            =DBSETPROP(viewfield,'Field','UpdateName',"dbo.test_a" + ;
               "."+ALLTRIM(fld_name))
         NEXT
         * Insert 100 records into the base table via remote view TESTA
         FOR j=1 TO 100
            INSERT INTO testa VALUES ; 
               (REPLICATE('0',6)+ALLTRIM(STR(j)),TTOC(DATETIME()+j))
         NEXT
         =TABLEUPDATE(.T.)
         SELECT testa
         USE testb IN 0
         * Get a Connection 'TEST1' is Busy message on next line
         * Select Ignore.
         USE testc IN 0
         CLOSE ALL
         gnConnHandle=SQLCONNECT('MyDSN','sa','')
         lnUseDB=0
         IF gnConnHandle > 0
            * Use the SQL Server PUBS database
            SQLCommand="USE PUBS"
            lnUseDB=sqlexec(gnConnHandle,SQLCommand)
            IF lnUseDB > 0
               * Drop Table TEST_A from the PUBS database
               SQLCommand="DROP TABLE TEST_A"
               =sqlexec(gnConnHandle,SQLCommand)
            ENDIF
            =sqldisconn(gnConnHandle)
         ENDIF
      ELSE
         =MESSAGEBOX('Unable to Create SQL Server Table',16)
      ENDIF
      SET SAFETY &lcsafestat
      SET EXCLUSIVE &lcexclstat
      SET MULTILOCKS &lcMultiLocks
      RETURN 


    3. From the Command window, type "DO REMOVIEW," and observe that the program runs with no error messages.


    4. From the Command window, type "DO REMOVIEW," and observe that an error occurs when the program attempts to open the view named TESTC.


    5. When the error message appears, select the Ignore option.


    6. Change the following line of code:
      
      =DBSETPROP(ViewName,'View','FetchSize',100) 


    7. to read as follows:
      
      =DBSETPROP(ViewName,'View','FetchSize',-1) 
    8. From the Command window, type "DO REMOVIEW," and observe that the program runs with no error messages.



    REFERENCES

    For additional information about Remote Views, please see the following articles in the Microsoft Knowledge Base:

    Q137944 How to Create a Remote Connection or View Programmatically

    Q174807 HOWTO: Edit the SQL Statement of a Remote or Local View

    Q191343 PRB: Connection Busy Error with a Shared Connection

    Q191344 PRB: Base Table Fields Changed with Remote View

    (c) Microsoft Corporation 1999, All Rights Reserved. Contributions by John Desch, Microsoft Corporation.

    Additional query words: KBDSE

    
    Keywords          : kbSQL kbVFp300 kbVFp300b kbVFp500 kbVFp500a kbVFp600 
    Version           : WINDOWS:3.0,3.0b,5.0,5.0a,6.0
    Platform          : WINDOWS 
    Issue type        : kbprb 

    Last Reviewed: March 27, 1999