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<title>OTL 4.0, Example 497 (Insert/Update/Select with MS SQL Server
2005 VARCHAR(MAX) in stream mode)</title>
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<h1>OTL 4.0, Example 497 (Insert/Update/Select with MS SQL Server 2005
VARCHAR(MAX)
in stream
mode)</h1>
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This example demonstrates INSERT, UPDATE, and SELECT statements with
the
MS SQL Server 2005 VARCHAR(MAX) datatype in the <a
href="otl3_lob_stream.htm">stream
mode</a>.
<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_MSSQL_2008">OTL_ODBC_MSSQL_2008</a> // Compile OTL 4/ODBC, MS SQL 2008<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(6000); // define long string variable<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<varchar_long>, "<br> ":f3<varchar_long>) ",<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.</pre>
<pre> int i,j;<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> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob2; // LOB stream for reading/writing unlimited number<br> // of bytes regardless of the buffer size.<br><br> for(i=1;i<=20;++i){<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> o<a
href="otl3_stream_class.htm#stream_write_lob"><<</a>lob2; // Initialize otl_lob_stream by writing it<br> // into otl_stream.<br><br> for(j=0;j<5000;++j)<br> f2[j]='*';<br> f2[5000]='?';<br> f2.<a
href="otl3_long_string.htm#set_len">set_len</a>(5001);<br><br> lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(5001+2123); // setting the total size of<br> // the VARCHAR(MAX) value to be written.<br> <br> lob<a
href="otl3_lob_stream.htm#write"><<</a>f2; // writing first chunk of the VARCHAR(MAX) value into lob<br><br><br> f2[2122]='?';<br> f2.set_len(2123); // setting the size of the second chunk<br><br> lob<<f2; // writing the second chunk of the VARCHAR(MAX) value into lob<br> lob.<a
href="otl3_lob_stream.htm">close</a>(); // closing the otl_lob_stream<br><br> for(j=0;j<5000;++j)<br> f2[j]='*';<br> f2[5000]='?';<br> f2.<a
href="otl3_long_string.htm#set_len">set_len</a>(5001);<br> lob2.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(5001+2123); // setting the total size of<br> // the VARCHAR(MAX) value to be written.<br> <br> lob2<a
href="otl3_lob_stream.htm#write"><<</a>f2; // writing first chunk of the VARCHAR(MAX) value into lob<br><br> f2[2122]='?';<br> f2.set_len(2123); // setting the size of the second chunk<br><br> lob2<<f2; // writing the second chunk of the VARCHAR(MAX) value into lob<br> lob2.<a
href="otl3_lob_stream.htm">close</a>(); // closing the otl_lob_stream<br><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; // 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><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<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><br> lob.<a
href="otl3_lob_stream.htm#set_len">set_len</a>(6001*4); // setting the total size of of the VARCHAR(MAX) value to be written<br> for(int i=1;i<=4;++i)<br> lob<a
href="otl3_lob_stream.htm#write"><<</a>f2; // writing chunks of the VARCHAR(MAX) value 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(3000); // define long string variable<br><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 VARCHAR(MAX) values, 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 VARCHAR(MAX) value<br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob2; // Stream for reading VARCHAR(MAX) value<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;<br> cout<<"f1="<<f1<<endl;<br> i<a
href="otl3_stream_class.htm#stream_read_lob">>></a>lob; // initializing LOB stream by reading the VARCHAR(MAX) value reference <br> // into the otl_lob_stream from the otl_stream.<br> i<a
href="otl3_stream_class.htm#stream_read_lob">>></a>lob2; // initializing LOB stream by reading the VARCHAR(MAX) value 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 VARCHAR(MAX) value<br> ++n;<br> lob<a
href="otl3_lob_stream.htm#read">>></a>f2; // reading a chunk of VARCHAR(MAX) value<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.<br> n=0;<br> while(!lob2.<a
href="otl3_lob_stream.htm#eof">eof</a>()){ // read while not "end-of-file" -- end of VARCHAR(MAX) value<br> ++n;<br> lob2<a
href="otl3_lob_stream.htm#read">>></a>f2; // reading a chunk of VARCHAR(MAX) value<br> cout<<" chunk #"<<n;<br> cout<<", f3="<<f2[0]<<f2[f2.len()-1]<<", len="<<f2.len()<<endl;<br> }<br> lob2.<a
href="otl3_lob_stream.htm#close">close</a>(); // closing the otl_lob_stream. <br> <br> }<br><br>}<br><br>int main()<br>{<br> <a
href="otl3_connect_class.htm">otl_connect::otl_initialize</a>(); // initialize the environment<br> try{<br><br> db.rlogon("scott/tiger@mssql2008"); // 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 VARCHAR(MAX), f3 VARCHAR(MAX))"<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.sqlstate<<endl; // print out SQLSTATE <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>}</pre>
<h2>
Output</h2>
<pre>f1=4<br> chunk #1, f2=**, len=2999<br> chunk #2, f2=**, len=2999<br> chunk #3, f2=*?, len=1126<br> chunk #1, f3=**, len=2999<br> chunk #2, f3=**, len=2999<br> chunk #3, f3=*?, len=1126<br>f1=5<br> chunk #1, f2=##, len=2999<br> chunk #2, f2=##, len=2999<br> chunk #3, f2=##, len=2999<br> chunk #4, f2=##, len=2999<br> chunk #5, f2=##, len=2999<br> chunk #6, f2=##, len=2999<br> chunk #7, f2=##, len=2999<br> chunk #8, f2=##, len=2999<br> chunk #9, f2=#?, len=12<br> chunk #1, f3=**, len=2999<br> chunk #2, f3=**, len=2999<br> chunk #3, f3=*?, len=1126<br>f1=6<br> chunk #1, f2=**, len=2999<br> chunk #2, f2=**, len=2999<br> chunk #3, f2=*?, len=1126<br> chunk #1, f3=**, len=2999<br> chunk #2, f3=**, len=2999<br> chunk #3, f3=*?, len=1126<br>f1=7<br> chunk #1, f2=**, len=2999<br> chunk #2, f2=**, len=2999<br> chunk #3, f2=*?, len=1126<br> chunk #1, f3=**, len=2999<br> chunk #2, f3=**, len=2999<br> chunk #3, f3=*?, len=1126<br>f1=8<br> chunk #1, f2=**, len=2999<br> chunk #2, f2=**, len=2999<br> chunk #3, f2=*?, len=1126<br> chunk #1, f3=**, len=2999<br> chunk #2, f3=**, len=2999<br> chunk #3, f3=*?, len=1126<br><br><hr
width="100%"></pre>
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