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<title>OTL 4.0, Example 596 (Datatype override in SELECT)</title>
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<h1>OTL 4.0, Example 53 (Datatype override in SELECT, Oracle 7)</h1>
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This example demonstrates a SELECT statement with a numeric column,
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.
<h2>Source Code</h2>
<pre>#include <iostream><br>using namespace std;<br><br>#include <stdio.h></pre>
<pre>#define <a href="otl3_compile.htm#OTL_ODBC_ENTERPRISEDB">OTL_ODBC_ENTERPRISEDB</a> // Compile OTL 4.0/EnterpriseDB-ODBC<br>// Uncomment the #define below when used in Linux / Unix<br>//#define OTL_ODBC_UNIX<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(12345678900000000+: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.set_column_type(1,otl_var_char,40); // use a string(40) instead of default double<br> i.open(50, // buffer size<br> "select * from test_tab "<br> "where f1>=12345678900000000+:f11<int> "<br> " and f1<=12345678900000000+: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 = 8, :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 = 4, :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/tiger@edbsql"); // connect to EDB<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 number, f2 varchar2(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 EDB<br><br> return 0;<br><br>}</pre>
<h2>
Output</h2>
<pre>f1=12345678900000008, f2=Name8<br>f1=12345678900000009, f2=Name9<br>f1=12345678900000010, f2=Name10<br>f1=12345678900000011, f2=Name11<br>f1=12345678900000012, f2=Name12<br>f1=12345678900000013, f2=Name13<br>f1=12345678900000014, f2=Name14<br>f1=12345678900000015, f2=Name15<br>f1=12345678900000016, f2=Name16<br>f1=12345678900000004, f2=Name4<br>f1=12345678900000005, f2=Name5<br>f1=12345678900000006, f2=Name6<br>f1=12345678900000007, f2=Name7<br>f1=12345678900000008, f2=Name8<br><hr
width="100%"></pre>
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