OTL 4.0, Example 123 (Insert/Update/Select with Oracle 8i BLOB in stream mode)

Example 123 (Insert/Update/Select with Oracle 8i BLOB in stream mode)

This example demonstrates INSERT, UPDATE, and SELECT statements with the Oracle 8i BLOB datatype in the stream mode. The example is similar to  example 57, and provided only as part of the package of examples to demonstrate the extended otl_lob_stream class.

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>
#define OTL_ORA8I // Compile OTL 4.0/OCI8
#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert()
// insert rows into table
{otl_long_string f2(6000); // define long string variable
 otl_stream o(1, // buffer size has to be set to 1 for operations with LOBs
              "insert into test_tab values(:f1<int>,empty_blob(),empty_blob()) "
              "returning f2, f3 into :f2<blob>,:f3<blob> ",
                 // SQL statement
              db // connect object
             );
 o.set_commit(0); // setting stream "auto-commit" to "off". It is required
                  // when LOB stream mode is used.
 int i,j;
 otl_lob_stream lob; // LOB stream for reading/writing unlimited number
                     // of bytes regardless of the buffer size.
 otl_lob_stream lob2; // LOB stream for reading/writing unlimited number
                     // of bytes regardless of the buffer size.

 for(i=1;i<=20;++i){
  o<<i;
  o<<lob; // Initialize otl_lob_stream by writing it
          // into otl_stream.
  o<<lob2; // Initialize otl_lob_stream by writing it
          // into otl_stream.

  for(j=0;j<5000;++j)
   f2[j]='*';
  f2[5000]='?';
  f2.set_len(5001);

  lob.set_len(5001+2123); // setting the total  size of
                          // the BLOB to be written.
  
  lob<<f2; // writing first chunk of the BLOB into lob


  f2[2122]='?';
  f2.set_len(2123); // setting the size of the second chunk

  lob<<f2; // writing the second chunk of the BLOB into lob
  lob.close(); // closing the otl_lob_stream

  for(j=0;j<5000;++j)
   f2[j]='*';
  f2[5000]='?';
  f2.set_len(5001);
  lob2.set_len(5001+2123); // setting the total  size of
                          // the BLOB to be written.
  
  lob2<<f2; // writing first chunk of the BLOB into lob

  f2[2122]='?';
  f2.set_len(2123); // setting the size of the second chunk

  lob2<<f2; // writing the second chunk of the BLOB into lob
  lob2.close(); // closing the otl_lob_stream

 }

 db.commit(); // committing transaction.
}
void update()
// insert rows in table
{
 otl_long_string f2(6200); // define long string variable

 otl_stream o(1, // buffer size has to be set to 1 for operations with LOBs
              "update test_tab "
              "   set f2=empty_blob() "
              "where f1=:f1<int> "
              "returning f2 into :f2<blob> ",
                 // SQL statement
              db // connect object
             );

  otl_lob_stream lob;

  o.set_commit(0); // setting stream "auto-commit" to "off". 


 for(int j=0;j<6000;++j){
  f2[j]='#';
 }

 f2[6000]='?';
 f2.set_len(6001);

 o<<5;
 o<<lob; // Initialize otl_lob_stream by writing it
         // into otl_stream.

 lob.set_len(6001*4); // setting the total size of of the BLOB to be written
 for(int i=1;i<=4;++i)
  lob<<f2; // writing chunks of the BLOB into the otl_lob_stream

 lob.close(); // closing the otl_lob_stream

 db.commit(); // committing transaction

}

void select()

 otl_long_string f2(3000); // define long string variable

 otl_stream i(10, // buffer size. To read BLOBs, it can be set to a size greater than 1
              "select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
                 // SELECT statement
              db // connect object
             ); 
   // create select stream
 
 int f1;
 otl_lob_stream lob; // Stream for reading BLOB
 otl_lob_stream lob2; // Stream for reading BLOB

 i<<4<<4; // assigning :f11 = 4, :f12 = 4
   // SELECT automatically executes when all input variables are
   // assigned. First portion of output rows is fetched to the buffer

 while(!i.eof()){ // while not end-of-data
  i>>f1;
  cout<<"f1="<<f1<<endl;
  i>>lob; // initializing BLOB stream by reading the BLOB reference 
          // into the otl_lob_stream from the otl_stream.
  i>>lob2; // initializing BLOB stream by reading the BLOB reference 
          // into the otl_lob_stream from the otl_stream.
  int n=0;
  while(!lob.eof()){ // read while not "end-of-file" -- end of BLOB
   ++n;
   lob>>f2; // reading a chunk of BLOB
   cout<<"   chunk #"<<n;
   cout<<", f2="<<f2[0]<<f2[f2.len()-1]<<", len="<<f2.len()<<endl;
  }
  lob.close(); // closing the otl_lob_stream.
  n=0;
  while(!lob2.eof()){ // read while not "end-of-file" -- end of BLOB
   ++n;
   lob2>>f2; // reading a chunk of BLOB
   cout<<"   chunk #"<<n;
   cout<<", f3="<<f2[0]<<f2[f2.len()-1]<<", len="<<f2.len()<<endl;
  }
  lob2.close(); // closing the otl_lob_stream. 
  
 }

}

int main()
{
 otl_connect::otl_initialize(); // initialize OCI environment
 try{

  db.rlogon("scott/tiger"); // connect to Oracle

  otl_cursor::direct_exec
   (
    db,
    "drop table test_tab",
    otl_exception::disabled // disable OTL exceptions
   ); // drop table

  otl_cursor::direct_exec
   (
    db,
    "create table test_tab(f1 number, f2 blob, f3 blob)"
    );  // create table

  insert(); // insert records into table
  update(); // update records in table
  select(); // select records from table

 }

 catch(otl_exception& p){ // intercept OTL exceptions
  cerr<<p.msg<<endl; // print out error message
  cerr<<p.stm_text<<endl; // print out SQL that caused the error
  cerr<<p.var_info<<endl; // print out the variable that caused the error
 }

 db.logoff(); // disconnect from Oracle

 return 0;

}

Output

f1=4
   chunk #1, f2=**, len=3000
   chunk #2, f2=**, len=3000
   chunk #3, f2=*?, len=1124
   chunk #1, f3=**, len=3000
   chunk #2, f3=**, len=3000
   chunk #3, f3=*?, len=1124
f1=5
   chunk #1, f2=##, len=3000
   chunk #2, f2=##, len=3000
   chunk #3, f2=?#, len=3000
   chunk #4, f2=##, len=3000
   chunk #5, f2=##, len=3000
   chunk #6, f2=##, len=3000
   chunk #7, f2=##, len=3000
   chunk #8, f2=##, len=3000
   chunk #9, f2=#?, len=4
   chunk #1, f3=**, len=3000
   chunk #2, f3=**, len=3000
   chunk #3, f3=*?, len=1124
f1=6
   chunk #1, f2=**, len=3000
   chunk #2, f2=**, len=3000
   chunk #3, f2=*?, len=1124
   chunk #1, f3=**, len=3000
   chunk #2, f3=**, len=3000
   chunk #3, f3=*?, len=1124
f1=7
   chunk #1, f2=**, len=3000
   chunk #2, f2=**, len=3000
   chunk #3, f2=*?, len=1124
   chunk #1, f3=**, len=3000
   chunk #2, f3=**, len=3000
   chunk #3, f3=*?, len=1124
f1=8
   chunk #1, f2=**, len=3000
   chunk #2, f2=**, len=3000
   chunk #3, f2=*?, len=1124
   chunk #1, f3=**, len=3000
   chunk #2, f3=**, len=3000
   chunk #3, f3=*?, len=1124

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Copyright © 1996-2017, Sergei Kuchin, email: skuchin@gmail.com, skuchin@gmail.com .

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