Xbase++ - Function DbSeek()

Positions the record pointer to a record based on the value of an index expression

DbSeek() can be used in conjunction with the ODBCDBE since the ODBCDBE is a compound DBE, consisting of the data, dictionary and the order component.

It is required to set the session property ODBCSSN_INDEX_AUTOOPEN to .T. (true) before retrieving the result set by DbUseArea().

Using the auto-open index does not create an index, but provides a virtual index, based on an ordered result set provided by the backend. The index key compromises either by the primary key or by a given ORDER BY clause.

DbSeek()

// This sample shows how to use a server-side 
// created index (created by CREATE INDEX). 

#include "odbcdbe.ch" 

PROCEDURE MAIN(cConnect) 
LOCAL oSesion 

   oSession := DacSession():new( cConnect ) 

   // turn Auto-open on 
   oSession:setProperty(ODBCSSN_INDEX_AUTOOPEN, .T.) 
   // table test has an index on field NAME 
   USE test NEW 
   ? IndexKey()                      // returns "NAME" 
   IF DbSeek("Meier") 
      ? "Found: ", Recno() 
   ENDIF 
RETURN

DbSeek() on ORDER BY

// This sample shows ho to use the order by clause 
// to get an index. 

#include "sqlcmd.ch" 

PROCEDURE MAIN 
LOCAL myConn 

    CREATE CONNECTION INTO myConn DATASOURCE "Oracle-Demo" ; 
           USER "Scott" PASSWORD "Tiger" 

    // turn Auto-open on 
    oSession:setProperty(ODBCSSN_INDEX_AUTOOPEN, .T.) 

    // a select statement with an ORDER BY clause 
    SQL "SELECT * FROM CUSTOMER ORDER BY Id, Name" 
    ? IndexKey()                      // returns "Str(Id,10,0) + Name" 
    IF DbSeek("0001"+"Meier") 
        ? "Found at", Recno() 
ELSE 
        ? "Not found." 
    ENDIF 
    CLOSE 
    DELETE CONNECTION myConn 
RETURN

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Function DbSeek() Professional