OTL 4.0, Example 224 (std::string and CLOBs, DB2)

Example 224 (std::string and CLOBs, DB2)

Source Code

#include <iostream>
#include <string>
using namespace std;
#define OTL_DB2_CLI // Compile OTL 4.0/DB2 CLI
#define OTL_STL // Enable STL compatibility mode

#if (defined(__clang__) || defined(__GNUC__)) && \
(defined(OTL_CPP_14_ON) || defined(OTL_CPP_17_ON))
#include <experimental/string_view>
#define OTL_STD_STRING_VIEW_CLASS std::experimental::string_view
#endif #elif defined(_MSC_VER) && (_MSC_VER>=1910) && defined(OTL_CPP_17_ON)
// VC++ 2017 or higher when /std=c++latest is used
#include <string_view>
#define OTL_STD_STRING_VIEW_CLASS std::string_view
#include <otlv4.h> // include the OTL 4.0 header file otl_connect db; // connect object void insert() // insert rows into table {
 string f2; 
 db.set_max_long_size(70000); // set maximum long string size for connect object

 otl_stream o(1, // buffer size has to be set to 1 for operations with LOBs
              "insert into test_tab values(:f1<int>,:f2<varchar_long>)",
                 // SQL statement
              db // connect object
             );

 for(int i=1;i<=20;++i){
  f2.assign(50001,' '); 
  for(int j=0;j<50000;++j)
   f2[j]='*';
  f2[50000]='?';
#if defined(OTL_STD_STRING_VIEW_CLASS)
OTL_STD_STRING_VIEW_CLASS f2_sv(f2.c_str(),f2.length());
o<<i<<f2_sv;
#else
o<<i<<f2;
#endif
 } } void select() {   string f2;  db.set_max_long_size(70000); // set maximum long string size for connect object  otl_stream i(1, // buffer size needs to be set to 1 for operations with LOBs               "select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",                  // SELECT statement               db // connect object              );     // create select stream    float f1;  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>>f2;   cout<<"f1="<<f1<<", f2="<<f2[0]<<f2[f2.length()-1]<<", len="       <<f2.length()<<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>>f2;   cout<<"f1="<<f1<<", f2="<<f2[0]<<f2[f2.length()-1]<<", len="       <<f2.length()<<endl;  } } int main() {  otl_connect::otl_initialize(); // initialize the database environment  try{   db.rlogon("scott/tiger@db2sql"); // 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 clob(4M))"     );  // 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=8, f2=*?, len=50001
f1=9, f2=*?, len=50001
f1=10, f2=*?, len=50001
f1=11, f2=*?, len=50001
f1=12, f2=*?, len=50001
f1=13, f2=*?, len=50001
f1=14, f2=*?, len=50001
f1=15, f2=*?, len=50001
f1=16, f2=*?, len=50001
f1=4, f2=*?, len=50001
f1=5, f2=*?, len=50001
f1=6, f2=*?, len=50001
f1=7, f2=*?, len=50001
f1=8, f2=*?, len=50001



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

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