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<title>OTL 4.0, Example 386 (Insert/Update/Select with Oracle
8i/9i/10g BLOB in stream mode and otl_long_string::set_last_piece())</title>
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<h1 align="center">OTL 4.0, Example 386 (Insert/Update/Select with
Oracle
8i/9i/10g BLOB in stream mode and otl_long_string::set_last_piece())</h1>
<p>This example demonstrates INSERT, UPDATE, and SELECT statements with
the Oracle 8 BLOB datatype in <a href="otl3_lob_stream.htm">stream mode</a>
and otl_long_string::<a href="otl3_long_string.htm#set_last_piece">set_last_piece</a>().<br>
</p>
<h2>Source Code</h2>
<pre>#include <iostream><br>using namespace std;<br><br>#include <stdio.h></pre>
<pre>#define OTL_ORA8I // Compile OTL 4.0/OCI8i<br>//#define OTL_ORA9I // Compile OTL 4.0/OCI9i<br>//#define OTL_ORA10G // Compile OTL 4.0/OCI10g<br>//#define OTL_ORA10G_R2 // Compile OTL 4.0/OCI10gR2<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>{<a
href="otl3_long_string.htm">otl_long_string</a> f2(60000); // define long string variable<br> <a
href="otl3_stream_class.htm">otl_stream</a> o(1, // buffer size has to be set to 1 for operations with LOBs<br> "insert into test_tab values(:f1<int>,empty_blob()) "<br> "returning f2 into :f2<<a
href="otl3_bind_variables.htm#blob">blob</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><br> for(int i=1;i<=20;++i){<br> for(int j=0;j<50000;++j)<br> f2[j]='*';<br> f2[50000]='?';<br> f2.<a
href="otl3_long_string.htm#set_len">set_len</a>(50001);<br><br> o<<i;<br><br> o<a
href="otl3_stream_class.htm#stream_write_lob"><<</a>lob; // Initialize otl_lob_stream by writing it<br> // into otl_stream. Weird, isn't it?<br><br>// OTL 4.0.138 and higher does not require the LOB's total length to be <br>// set beforehand. Instead, otl_long_string::last_piece can be used.<br>// lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(50001+23123); // setting the total size of<br>// // the BLOB to be written.<br>// // It is required for compatibility<br>// // with earlier releases of OCI8: OCI8.0.3, OCI8.0.4.<br> <br> f2.<a
href="otl3_long_string.htm#set_last_piece">set_last_piece</a>(false);<br> lob<a
href="otl3_lob_stream.htm#write"><<</a>f2; // writing first chunk of the BLOB into lob<br><br> f2[23122]='?';<br> f2.set_len(23123); // setting the size of the second chunk<br><br> f2.<a
href="otl3_long_string.htm#set_last_piece">set_last_piece</a>(true);<br> lob<<f2; // writing the second chunk of the BLOB 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>{ </pre>
<pre> <a href="otl3_long_string.htm">otl_long_string</a> f2(6200); // define long string variable<br><br> <a
href="otl3_stream_class.htm">otl_stream</a> o(1, // buffer size has to be set to 1 for operations with LOBs<br> "update test_tab "<br> " set f2=empty_blob() "<br> "where f1=:f1<int> "<br> "returning f2 into :f2<<a
href="otl3_bind_variables.htm#blob">blob</a>> ",<br> // SQL statement<br> db // connect object<br> );<br><br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob;<br><br> o.<a
href="otl3_stream_class.htm#set_commit">set_commit</a>(0); // setting stream "auto-commit" to "off". <br><br><br> for(int j=0;j<6000;++j){<br> f2[j]='#';<br> }<br><br> f2[6000]='?';<br> f2.<a
href="otl3_long_string.htm#set_len">set_len</a>(6001);<br><br> o<<5;<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>// OTL 4.0.138 and higher does not require the LOB's total length to be <br>// set beforehand. Instead, otl_long_string::last_piece can be used.<br>// lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(6001*4); // setting the total size of of the BLOB to be written<br> for(int i=1;i<=4;++i){<br> f2.<a
href="otl3_long_string.htm#set_last_piece">set_last_piece</a>(i==4);<br> lob<a
href="otl3_lob_stream.htm#write"><<</a>f2; // writing chunks of the BLOB into the otl_lob_stream<br> }<br> lob.<a
href="otl3_lob_stream.htm#close">close</a>(); // closing the otl_lob_stream<br><br> db.commit(); // committing transaction<br><br>}<br><br>void select()<br>{ <br> <a
href="otl3_long_string.htm">otl_long_string</a> f2(20000); // define long string variable<br><br> <a
href="otl3_stream_class.htm">otl_stream</a> i(10, // buffer size. To read BLOBs, it can be set to a size greater than 1<br> "select * from test_tab where f1>=:f<int> and f1<=:f*2",<br> // SELECT statement<br> db // connect object<br> ); <br> // create select stream<br> <br> float f1;<br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob; // Stream for reading BLOB<br><br> i<<4; // assigning :f = 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<<endl;<br> i<a
href="otl3_stream_class.htm#stream_read_lob">>></a>lob; // initializing BLOB stream by reading the BLOB reference <br> // into the otl_lob_stream from the otl_stream.<br> int n=0;<br> while(!lob.<a
href="otl3_lob_stream.htm#eof">eof</a>()){ // read while not "end-of-file" -- end of BLOB<br> ++n;<br> lob<a
href="otl3_lob_stream.htm#read">>></a>f2; // reading a chunk of BLOB<br> cout<<" chunk #"<<n;<br> cout<<", f2="<<f2[0]<<f2[f2.len()-1]<<", len="<<f2.len()<<endl;<br> }<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 OCI environment<br> try{<br><br> db.rlogon("scott/tiger"); // connect to Oracle<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 blob)"<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 Oracle<br><br> return 0;<br><br>}<br></pre>
<h2>Output</h2>
<pre>f1=4<br> chunk #1, f2=**, len=20000<br> chunk #2, f2=**, len=20000<br> chunk #3, f2=**, len=20000<br> chunk #4, f2=*?, len=13124<br>f1=5<br> chunk #1, f2=##, len=20000<br> chunk #2, f2=#?, len=4004<br>f1=6<br> chunk #1, f2=**, len=20000<br> chunk #2, f2=**, len=20000<br> chunk #3, f2=**, len=20000<br> chunk #4, f2=*?, len=13124<br>f1=7<br> chunk #1, f2=**, len=20000<br> chunk #2, f2=**, len=20000<br> chunk #3, f2=**, len=20000<br> chunk #4, f2=*?, len=13124<br>f1=8<br> chunk #1, f2=**, len=20000<br> chunk #2, f2=**, len=20000<br> chunk #3, f2=**, len=20000<br> chunk #4, f2=*?, len=13124<br><br><br><hr
width="100%"></pre>
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<p>Copyright © 1996, 2008, Sergei Kuchin, email: <a
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<a href="mailto:skuchin@gmail.com">skuchin@gmail.com</a>
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