OTL 4.0, Example 273 (Simple Unicode Insert/Select with NTEXT, and LOB streams)

Example 273 (Simple Unicode Insert/Select with NTEXT, and LOB streams)

This example demonstrates simple Unicode INSERT, SELECT, and constant SQL statements with NTEXT columns, and LOB streams.

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>
#define OTL_ODBC_MSSQL_2008 // Compile OTL 4/ODBC, MS SQL 2008
//#define OTL_ODBC // Compile OTL 4/ODBC. Uncomment this when used with MS SQL 7.0/ 2000
#define OTL_UNICODE // Enable Unicode OTL for ODBC
#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert()
// insert rows into table

 otl_long_unicode_string f2(6000); // define long unicode string variable

 otl_stream o;

o.set_lob_stream_mode(true); // set the "lob stream mode" flag
o.open(1, // buffer size has to be set to 1 for operations with CLOBs
        "insert into test_tab values(:f1<int>,:f2<varchar_long>)",
          // SQL statement
         db // connect object
        );

 o.set_commit(0); // setting stream "auto-commit" to "off". It is required
                  // when LOB stream mode is used.
 otl_lob_stream lob; // LOB stream for reading/writing unlimited number
                     // of bytes regardless of the buffer size.

 int i,j;

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

  for(j=0;j<5000;++j)
   f2[j]=(unsigned short) '*'; // ASCII to Unicode.
  f2[5000]= (unsigned short) '?'; // ASCII to Unicode
  f2.set_len(5001);

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

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

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

 }

 db.commit(); // committing transaction.

}

void select()

 otl_long_unicode_string f2(6000); // define Unicode long string variable

 otl_stream i;
i.set_lob_stream_mode(true); // set the "lob stream mode" flag
i.open(1, // buffer size needs to be set to 1 in this case
        "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 CLOB

 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 CLOB stream by reading the CLOB reference 
          // into the otl_lob_stream from the otl_stream.
  int n=0;
  while(!lob.eof()){ // read while not "end-of-file" -- end of CLOB
   ++n;
   lob>>f2; // reading a chunk of CLOB
   cout<<"   chunk #"<<n;
   cout<<", f2="
       <<(char)f2[0] // Unicode to ASCII
       <<(char)f2[f2.len()-1]<<", len="<<f2.len()<<endl;
  }
  lob.close(); // closing the otl_lob_stream. This step may be skipped.  
 }
}
int main()
{
 otl_connect::otl_initialize(); // initialize the database API environment
 try{

  db.rlogon("scott/tiger@mssql2008"); // connect to the database

  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 int, f2 ntext)"
    );  // create table

  insert(); // insert records into 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 the database

 return 0;

}

Output

f1=4
chunk #1, f2=**, len=5999
chunk #2, f2=*?, len=1125
f1=5
chunk #1, f2=**, len=5999
chunk #2, f2=*?, len=1125
f1=6
chunk #1, f2=**, len=5999
chunk #2, f2=*?, len=1125
f1=7
chunk #1, f2=**, len=5999
chunk #2, f2=*?, len=1125
f1=8
chunk #1, f2=**, len=5999
chunk #2, f2=*?, len=1125


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

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