📄 otl4_ex417.htm
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<title>Example 417 (otl_stream::clean(), cancelling SELECT's fetch
sequence, Sybase SQL Server)</title>
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<h1>OTL 4.0, Example 417 (otl_stream::clean(), cancelling SELECT's
fetch sequence,
Sybase SQL Server)</h1>
</center>
This example demonstrates the extended functionality of the <a
href="otl3_stream_class.htm#clean">otl_stream::clean()</a>
function.
<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<float>,: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<<(float)i<<tmp;<br> }<br>}<br><br>void select()<br>{ <br> <a
href="otl3_stream_class.htm">otl_stream</a> i(50, // buffer size<br> "select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",<br> // SELECT statement<br> db // connect object<br> ); <br> // create select stream<br> <br> float f1;<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> int n=0;<br> cout<<"====> Starting a fetch sequence...."<<endl;<br> while(!i.eof()){ // while not end-of-data<br> ++n;<br> i>>f1>>f2;<br> cout<<"f1="<<f1<<", f2="<<f2<<endl;<br> if(n>=3){<br> // breaking the fetch sequence after 3 rows are fetched, and <br> // "cleaning" the state of the SELECT stream.<br> cout<<"Cancelling the fetch sequence after 3 rows are fetched"<<endl;<br> i.<a
href="otl3_stream_class.htm#clean">clean()</a>;<br> break;<br> }<br> }<br><br> cout<<"====> Starting another fetch sequence..."<<endl;<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/tigger@sybsql"); // connect to MS SQL Server<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.sqlstate<<endl; // print out SQLSTATE<br> cerr<<p.var_info<<endl; // print out the variable that caused the error<br> }<br><br> db.logoff(); // disconnect from MS SQL Server<br><br> return 0;<br><br>}</pre>
<h2>
Output</h2>
<pre>====> Starting a fetch sequence....<br>f1=8, f2=Name8<br>f1=9, f2=Name9<br>f1=10, f2=Name10<br>Cancelling the fetch sequence after 3 rows are fetched<br>====> Starting another fetch sequence...<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><br><br><hr
width="100%"></pre>
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