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<!DOCTYPE html PUBLIC "-//w3c//dtd html 4.0 transitional//en"><html><head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="Author" content="Sergei Kuchin"> <meta name="GENERATOR" content="Mozilla/4.7 [en] (WinNT; I) [Netscape]"> <meta name="KeyWords" content="OTL, Oracle, ODBC, DB2, CLI, database API, C++, Template Library"> <title>OTL 4.0, Example 552 (Datatype override in SELECT, Sybase SQLServer)</title></head><body><center><h1>OTL 4.0, Example 552 (Datatype override in SELECT, Sybase SQLServer)</h1></center>This example demonstrates a SELECT statement with a numeric column,beingconverted into a null terminated string. It is a useful technique whenthere is a need to read and write numbers, which are larger than 16digits.<h2>Source Code</h2><pre>#include <iostream><br>using namespace std;<br><br>#include <stdio.h></pre><pre>#define OTL_ODBC_UNIX // Compile OTL 4.0/ODBC<br>#include <otlv4.h> // include the OTL 4.0 header file<br><br><a href="otl3_connect_class.htm">otl_connect</a> db; // connect object<br><br>void insert()<br>// insert rows into table<br>{ <br> <a href="otl3_stream_class.htm">otl_stream</a> o(50, // buffer size<br> "insert into test_tab values(:f1<int>,:f2<char[31]>)", <br> // SQL statement<br> db // connect object<br> );<br> char tmp[32];<br><br> for(int i=1;i<=100;++i){<br> sprintf(tmp,"Name%d",i);<br> o<<i<<tmp;<br> }<br>}<br><br>void select()<br>{ <br> <a href="otl3_stream_class.htm">otl_stream</a> i;<br><br> i.<a href="otl3_stream_class.htm#set_column_type">set_column_type</a>(1,otl_var_char,40); // use a string(40) instead of default double<br> i.<a href="otl3_stream_class.htm#open">open</a>(50, // buffer size<br> "select f1, f2 from test_tab "<br> "where f1>=:f11<int> "<br> " and f1<=:f12<int>*2",<br> // SELECT statement<br> db // connect object<br> ); <br> // create select stream<br> <br> char f1[40];<br> char f2[31];<br><br> i<<8<<8; // assigning :f11, :f12 = 8<br> // SELECT automatically executes when all input variables are<br> // assigned. First portion of output rows is fetched to the buffer<br><br> while(!i.eof()){ // while not end-of-data<br> i>>f1>>f2;<br> cout<<"f1="<<f1<<", f2="<<f2<<endl;<br> }<br><br> i<<4<<4; // assigning :f11, :f12 = 4<br> // SELECT automatically executes when all input variables are<br> // assigned. First portion of output rows is fetched to the buffer<br><br> while(!i.eof()){ // while not end-of-data<br> i>>f1>>f2;<br> cout<<"f1="<<f1<<", f2="<<f2<<endl;<br> }<br><br>}<br><br>int main()<br>{<br> <a href="otl3_connect_class.htm">otl_connect::otl_initialize</a>(); // initialize ODBC environment<br> try{<br><br> db.rlogon("scott/tigger@freetds_sybsql"); // connect to ODBC<br><br> <a href="otl3_const_sql.htm">otl_cursor::direct_exec<br></a> (<br> db,<br> "drop table test_tab",<br> otl_exception::disabled // disable OTL exceptions<br> ); // drop table<br><br> <a href="otl3_const_sql.htm">otl_cursor::direct_exec<br></a> (<br> db,<br> "create table test_tab(f1 int, f2 varchar(30))"<br> ); // create table<br><br> insert(); // insert records into table<br> select(); // select records from table<br><br> }<br><br> catch(<a href="otl3_exception_class.htm">otl_exception</a>& p){ // intercept OTL exceptions<br> cerr<<p.msg<<endl; // print out error message<br> cerr<<p.stm_text<<endl; // print out SQL that caused the error<br> cerr<<p.var_info<<endl; // print out the variable that caused the error<br> }<br><br> db.logoff(); // disconnect from ODBC<br><br> return 0;<br><br>}</pre><h2>Output</h2><pre>f1=8, f2=Name8<br>f1=9, f2=Name9<br>f1=10, f2=Name10<br>f1=11, f2=Name11<br>f1=12, f2=Name12<br>f1=13, f2=Name13<br>f1=14, f2=Name14<br>f1=15, f2=Name15<br>f1=16, f2=Name16<br>f1=4, f2=Name4<br>f1=5, f2=Name5<br>f1=6, f2=Name6<br>f1=7, f2=Name7<br>f1=8, f2=Name8<br><br><hr width="100%"></pre><center><a href="otl3_examples.htm">Examples</a> <a href="otl3.htm">Contents</a><a href="home.htm">GoHome</a></center><p>Copyright © 1996, 2008, Sergei Kuchin, email: <a href="mailto:skuchin@aceweb.com">skuchin@aceweb.com</a>,<a href="mailto:skuchin@gmail.com">skuchin@gmail.com/a>.<script language="JavaScript"><!-- hide from old browsers var modDate = new Date(document.lastModified) document.write("<i> Last Updated:</i> " + (modDate.getMonth()+1) + "/" + modDate.getDate() + "/" + "0"+(modDate.getYear())%100+"."); //--> </script></a></p><p><i>Permission to use, copy,modify and redistribute this documentforany purpose is hereby granted without fee, provided that the abovecopyrightnotice appear in all copies.</i></p></body></html>⌨️ 快捷键说明
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