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<title>OTL 4.0, Example 384 (Insert/Update/Select, MAX/DB LONG
VARCHAR in stream mode, and std::strings)</title>
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<h1 align="center">OTL 4.0, Example 384 (Insert/Update/Select,
MAX/DB LONG VARCHAR in stream mode, and std:strings)</h1>
<p>This example demonstrates INSERT, UPDATE, and SELECT statements with
the MAX/DB LONG VARCHAR datatype in <a href="otl3_lob_stream.htm">stream
mode</a> and <span style="font-style: italic;">std::strings</span>.<br>
</p>
<h2>Source Code</h2>
<pre>#include <iostream><br>#include <string><br>using namespace std;<br><br>#include <stdio.h></pre>
<pre>#define <a href="otl3_compile.htm#OTL_ODBC">OTL_ODBC</a> // Compile OTL 4.0/ODBC<br>// #define OTL_ODBC_UNIX // uncomment this line if UnixODBC is used<br>#define OTL_STL // enable OTL support for STL<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> string f2; <br> <a
href="otl3_stream_class.htm">otl_stream</a> o; // defined an otl_stream variable<br> o.<a
href="otl3_stream_class.htm#set_lob_stream_mode">set_lob_stream_mode</a>(true); // set the "lob stream mode" flag<br> o.<a
href="otl3_stream_class.htm#open">open</a>(1, // buffer size has to be set to 1 for operations with LOBs<br> "insert into test_tab values(:f1<int>,:f2<<a
href="otl3_bind_variables.htm#varchar_long">varchar_long</a>>) ",<br> // SQL statement<br> db // connect object<br> );<br> o.<a
href="otl3_stream_class.htm#set_commit">set_commit</a>(0); // setting stream "auto-commit" to "off". It is required<br> // when LOB stream mode is used.<br><br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob; // LOB stream for reading/writing unlimited number<br> // of bytes regardless of the buffer size.<br> for(int i=1;i<=20;++i){<br> f2.erase();<br> f2.append(50000,'*');<br> f2 += '?';<br> o<<i;<br> o<a
href="otl3_stream_class.htm#stream_write_lob"><<</a>lob; // Initialize otl_lob_stream by writing it<br> // into otl_stream<br><br> lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(50001+23123); // setting the total size of<br> // the TEXT to be written.<br> // It is required for bakward compatibility<br> <br> lob<a
href="otl3_lob_stream.htm#write_string"><<</a>f2; // writing first chunk of the TEXT into lob<br><br> f2.erase();<br> f2.append(23122,'*');<br> f2 += '?';<br> lob<<f2; // writing the second chunk of the TEXT into lob<br> lob.<a
href="otl3_lob_stream.htm">close</a>(); // closing the otl_lob_stream<br> }<br><br> db.commit(); // committing transaction.<br>}</pre>
<pre>void update()<br>// insert rows in table<br>{ <br> string f2; <br> <a
href="otl3_stream_class.htm">otl_stream</a> o; // defined an otl_stream variable<br> o.<a
href="otl3_stream_class.htm#set_lob_stream_mode">set_lob_stream_mode</a>(true); // set the "lob stream mode" flag<br> o.<a
href="otl3_stream_class.htm#open">open</a>(1, // buffer size has to be set to 1 for operations with LOBs<br> "update test_tab "<br> " set f2=:f2<varchar_long> "<br> "where f1=:f1<int> ",<br> // SQL statement<br> db // connect object<br> );<br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob;<br> o.<a
href="otl3_stream_class.htm#set_commit">set_commit</a>(0); // setting stream "auto-commit" to "off". <br> f2.append(6000,'#');<br> f2+='?';<br> o<a
href="otl3_stream_class.htm#stream_write_lob"><<</a>lob; // Initialize otl_lob_stream by writing it<br> // into otl_stream.<br> o<<5;<br> lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(6001*4); // setting the total size of of the TEXT to be written<br> for(int i=1;i<=4;++i)<br> lob<a
href="otl3_lob_stream.htm#write_string"><<</a>f2; // writing chunks of the TEXT into the otl_lob_stream<br> lob.<a
href="otl3_lob_stream.htm#close">close</a>(); // closing the otl_lob_stream<br> db.commit(); // committing transaction<br><br>}<br><br>void select()<br>{ <span
style="text-decoration: underline;"><br></span> string f2;<br> <a
href="otl3_stream_class.htm">otl_stream</a> i; // defined an otl_stream variable<br> i.<a
href="otl3_stream_class.htm#set_lob_stream_mode">set_lob_stream_mode</a>(true); // set the "lob stream mode" flag<br> i.<a
href="otl3_stream_class.htm#open">open</a>(1, // buffer size. To read TEXTs, it should be set to 1<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> int f1;<br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob; // Stream for reading TEXT<br><br> lob.<a
href="otl3_lob_stream.htm#SET_STRING_BUFFER">setStringBuffer</a>(40000); // Set a bigger internal buffer (default is 4096 bytes)<br> // for reading chunks of the TEXT, before each chunk<br> // gets appended to the output string.<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;<br> cout<<"f1="<<f1;<br> i<a
href="otl3_stream_class.htm#stream_read_lob">>></a>lob; // initializing TEXT stream by reading the TEXT reference <br> // into the otl_lob_stream from the otl_stream.<br> lob<a
href="otl3_lob_stream.htm#STRING_READ">>></a>f2;<br> cout<<", f2="<<f2[0]<<f2[f2.length()-1]<<", len="<<(int)f2.length()<<endl;<br> lob.<a
href="otl3_lob_stream.htm#close">close</a>(); // closing the otl_lob_stream. This step may be skipped.<br> <br> }<br><br>}<br><br>int main()<br>{<br> <a
href="otl3_connect_class.htm">otl_connect::otl_initialize</a>(); // initialize the database API environment<br> try{<br><br> db.rlogon("scott/tiger@sapdbsql"); // connect to the database<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 long varchar)"<br> ); // create table<br><br> insert(); // insert records into table<br> update(); // update records in 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 the database<br><br> return 0;<br><br>}<br></pre>
<h2>Output</h2>
<pre>f1=4, f2=*?, len=73124<br>f1=5, f2=#?, len=24004<br>f1=6, f2=*?, len=73124<br>f1=7, f2=*?, len=73124<br>f1=8, f2=*?, len=73124<br><br><hr
width="100%"></pre>
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<p>Copyright © 1996, 2008, Sergei Kuchin, email: <a
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