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<TITLE>OTL 4.0, Example 57 (Insert/Update/Select with Oracle 8 BLOB in stream mode)</TITLE>
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<H1 ALIGN=CENTER>OTL 4.0, Example 57 (Insert/Update/Select with Oracle
8 BLOB in stream mode)</H1>
<H1>Example 57 (Insert/Update/Select with Oracle 8 BLOB in stream mode)</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>.</P>
<H2>Source Code</H2>
<PRE>#include <iostream>
using namespace std;
#include <stdio.h></PRE>
<PRE>#define OTL_ORA8 // Compile OTL 4.0/OCI8
#include <otlv4.h> // include the OTL 4.0 header file
<A HREF="otl3_connect_class.htm">otl_connect</A> db; // connect object
void insert()
// insert rows into table
{<A HREF="otl3_long_string.htm">otl_long_string</A> f2(60000); // define long string variable
<A HREF="otl3_stream_class.htm">otl_stream</A> o(1, // buffer size has to be set to 1 for operations with LOBs
"insert into test_tab values(:f1<int>,empty_blob()) "
"returning f2 into :f2<<A HREF="otl3_bind_variables.htm#blob">blob</A>> ",
// SQL statement
db // connect object
);
o.<A HREF="otl3_stream_class.htm#set_commit">set_commit</A>(0); // setting stream "auto-commit" to "off". It is required
// when LOB stream mode is used.
<A HREF="otl3_lob_stream.htm">otl_lob_stream</A> lob; // LOB stream for reading/writing unlimited number
// of bytes regardless of the buffer size.
for(int i=1;i<=20;++i){
for(int j=0;j<50000;++j)
f2[j]='*';
f2[50000]='?';
f2.<A HREF="otl3_long_string.htm#set_len">set_len</A>(50001);
o<<i;
o<A HREF="otl3_stream_class.htm#stream_write_lob"><<</A>lob; // Initialize otl_lob_stream by writing it
// into otl_stream. Weird, isn't it?
lob.<A HREF="otl3_lob_stream.htm#set_len">set_len</A>(50001+23123); // setting the total size of
// the BLOB to be written.
// It is required for compatibility
// with earlier releases of OCI8: OCI8.0.3, OCI8.0.4.
lob<A HREF="otl3_lob_stream.htm#write"><<</A>f2; // writing first chunk of the BLOB into lob
f2[23122]='?';
f2.set_len(23123); // setting the size of the second chunk
lob<<f2; // writing the second chunk of the BLOB into lob
lob.<A HREF="otl3_lob_stream.htm">close</A>(); // closing the otl_lob_stream
}
db.commit(); // committing transaction.
}</PRE>
<PRE>void update()
// insert rows in table
{ </PRE>
<PRE> <A HREF="otl3_long_string.htm">otl_long_string</A> f2(6200); // define long string variable
<A HREF="otl3_stream_class.htm">otl_stream</A> o(1, // buffer size has to be set to 1 for operations with LOBs
"update test_tab "
" set f2=empty_blob() "
"where f1=:f1<int> "
"returning f2 into :f2<<A HREF="otl3_bind_variables.htm#blob">blob</A>> ",
// SQL statement
db // connect object
);
<A HREF="otl3_lob_stream.htm">otl_lob_stream</A> lob;
o.<A HREF="otl3_stream_class.htm#set_commit">set_commit</A>(0); // setting stream "auto-commit" to "off".
for(int j=0;j<6000;++j){
f2[j]='#';
}
f2[6000]='?';
f2.<A HREF="otl3_long_string.htm#set_len">set_len</A>(6001);
o<<5;
o<A HREF="otl3_stream_class.htm#stream_write_lob"><<</A>lob; // Initialize otl_lob_stream by writing it
// into otl_stream.
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
for(int i=1;i<=4;++i)
lob<A HREF="otl3_lob_stream.htm#write"><<</A>f2; // writing chunks of the BLOB into the otl_lob_stream
lob.<A HREF="otl3_lob_stream.htm#close">close</A>(); // closing the otl_lob_stream
db.commit(); // committing transaction
}
void select()
{
<A HREF="otl3_long_string.htm">otl_long_string</A> f2(20000); // define long string variable
<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
"select * from test_tab where f1>=:f<int> and f1<=:f*2",
// SELECT statement
db // connect object
);
// create select stream
float f1;
<A HREF="otl3_lob_stream.htm">otl_lob_stream</A> lob; // Stream for reading BLOB
i<<4; // assigning :f = 4
// SELECT automatically executes when all input variables are
// assigned. First portion of output rows is fetched to the buffer
while(!i.eof()){ // while not end-of-data
i>>f1;
cout<<"f1="<<f1<<endl;
i<A HREF="otl3_stream_class.htm#stream_read_lob">>></A>lob; // initializing BLOB stream by reading the BLOB reference
// into the otl_lob_stream from the otl_stream.
int n=0;
while(!lob.<A HREF="otl3_lob_stream.htm#eof">eof</A>()){ // read while not "end-of-file" -- end of BLOB
++n;
lob<A HREF="otl3_lob_stream.htm#read">>></A>f2; // reading a chunk of BLOB
cout<<" chunk #"<<n;
cout<<", f2="<<f2[0]<<f2[f2.len()-1]<<", len="<<f2.len()<<endl;
}
lob.<A HREF="otl3_lob_stream.htm#close">close</A>(); // closing the otl_lob_stream. This step may be skipped.
}
}
int main()
{
<A HREF="otl3_connect_class.htm">otl_connect::otl_initialize</A>(); // initialize OCI environment
try{
db.rlogon("scott/tiger"); // connect to Oracle
<A HREF="otl3_const_sql.htm">otl_cursor::direct_exec
</A> (
db,
"drop table test_tab",
otl_exception::disabled // disable OTL exceptions
); // drop table
<A HREF="otl3_const_sql.htm">otl_cursor::direct_exec
</A> (
db,
"create table test_tab(f1 number, f2 blob)"
); // create table
insert(); // insert records into table
update(); // update records in table
select(); // select records from table
}
catch(<A HREF="otl3_exception_class.htm">otl_exception</A>& p){ // intercept OTL exceptions
cerr<<p.msg<<endl; // print out error message
cerr<<p.stm_text<<endl; // print out SQL that caused the error
cerr<<p.var_info<<endl; // print out the variable that caused the error
}
db.logoff(); // disconnect from Oracle
return 0;
}
</PRE>
<H2>Output</H2>
<PRE>f1=4
chunk #1, f2=**, len=20000
chunk #2, f2=**, len=20000
chunk #3, f2=**, len=20000
chunk #4, f2=*?, len=13124
f1=5
chunk #1, f2=##, len=20000
chunk #2, f2=#?, len=4004
f1=6
chunk #1, f2=**, len=20000
chunk #2, f2=**, len=20000
chunk #3, f2=**, len=20000
chunk #4, f2=*?, len=13124
f1=7
chunk #1, f2=**, len=20000
chunk #2, f2=**, len=20000
chunk #3, f2=**, len=20000
chunk #4, f2=*?, len=13124
f1=8
chunk #1, f2=**, len=20000
chunk #2, f2=**, len=20000
chunk #3, f2=**, len=20000
chunk #4, f2=*?, len=13124
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<P>Copyright © 1996, 2008, Sergei Kuchin, email: <A HREF="mailto:skuchin@aceweb.com">skuchin@aceweb.com</A>,
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