OTL 4.0, Example 514 (Group data type override in SELECT, MS SQL Server)

This example demonstrates a SELECT statement with a group of numeric columns, being converted into a null terminated string. It is a useful technique when there is a need to read and write number, which are larger than 16 digits. Also, this example demonstrates the overriding of datetime columns.

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>
#define OTL_ODBC_MSSQL_2005 // Compile OTL 4/ODBC, MS SQL 2005
#define OTL_FREETDS_ODBC_WORKAROUNDS // Enable the FreeTDS / ODBC workarounds for MS SQL
//#define OTL_ODBC // Compile OTL 4/ODBC. Uncomment this when used with MS SQL 7.0/ 2000
//#define OTL_ODBC_UNIX // Compile OTL 4 / ODBC. Uncomment this when used in Linux / Unix
#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert()
// insert rows into table

 otl_stream o(50, // buffer size
              "insert into test_tab values(12345678900000000+convert(numeric,:f1<int>),:f11<int>,:f2<char[31]>, GETDATE())", 
                 // SQL statement
              db // connect object
             );
 char tmp[32];

 for(int i=1;i<=100;++i){
  sprintf(tmp,"Name%d",i);
  o<<i<<i<<tmp;
 }
}

void select()

 otl_stream i;

 i.set_all_column_types(otl_all_num2str | otl_all_date2str);
// map all numeric columns to strings as well as
// map all date columns to strings

 i.open(50, // buffer size
        "select * from test_tab "
"where f1>=12345678900000000+convert(numeric,:f11<int>) "
" and f1<=12345678900000000+convert(numeric,:f12<int>)*2",
           // SELECT statement
        db // connect object
       ); 
   // create select stream
 
 char f1[40];
char f11[40];
 char f2[31];
char f3[40];

 i<<8<<8;
   // 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>>f11>>f2>>f3;
  cout<<"f1="<<f1<<", f11="<<f11<<", f2="<<f2<<", f3="<<f3<<endl;
 }

 i<<4<<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>>f11>>f2>>f3;
  cout<<"f1="<<f1<<", f11="<<f11<<", f2="<<f2<<", f3="<<f3<<endl;
 }

}

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

  db.rlogon("scott/tiger@freetds_mssql"); // connect to ODBC

  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 numeric, f11 int, f2 varchar(30), f3 datetime)"
    );  // 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 ODBC

 return 0;

}

Output

f1=12345678900000008, f11=8, f2=Name8, f3=2001-02-03 21:29:49.560
f1=12345678900000009, f11=9, f2=Name9, f3=2001-02-03 21:29:49.560
f1=12345678900000010, f11=10, f2=Name10, f3=2001-02-03 21:29:49.560
f1=12345678900000011, f11=11, f2=Name11, f3=2001-02-03 21:29:49.560
f1=12345678900000012, f11=12, f2=Name12, f3=2001-02-03 21:29:49.560
f1=12345678900000013, f11=13, f2=Name13, f3=2001-02-03 21:29:49.560
f1=12345678900000014, f11=14, f2=Name14, f3=2001-02-03 21:29:49.560
f1=12345678900000015, f11=15, f2=Name15, f3=2001-02-03 21:29:49.560
f1=12345678900000016, f11=16, f2=Name16, f3=2001-02-03 21:29:49.560
f1=12345678900000004, f11=4, f2=Name4, f3=2001-02-03 21:29:49.560
f1=12345678900000005, f11=5, f2=Name5, f3=2001-02-03 21:29:49.560
f1=12345678900000006, f11=6, f2=Name6, f3=2001-02-03 21:29:49.560
f1=12345678900000007, f11=7, f2=Name7, f3=2001-02-03 21:29:49.560
f1=12345678900000008, f11=8, f2=Name8, f3=2001-02-03 21:29:49.560


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