📄 otl4_ex499.htm
字号:
<!DOCTYPE html PUBLIC "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=iso-8859-1">
<meta name="Author" content="Sergei Kuchin">
<meta name="GENERATOR"
content="Mozilla/4.77 [en] (Win95; U) [Netscape]">
<meta name="KeyWords"
content="OTL, Oracle, ODBC, DB2, CLI, database API, C++, Template Library">
<title>OTL 4.0, Example 499 (Simple Unicode Insert/Select with MS SQL
2005 NVARCHAR(MAX), and LOB streams)</title>
</head>
<body>
<center>
<h1>OTL 4.0, Example 499 (Simple Unicode Insert/Select with MS SQL 2005
NVARCHAR(MAX), and
LOB streams)</h1>
</center>
This example demonstrates simple Unicode INSERT, SELECT, and constant
SQL
statements with MS SQL 2005 NVARCHAR(MAX) columns, and <a
href="otl3_lob_stream.htm">LOB
streams</a>. <br>
<h2>Source Code</h2>
<pre>#include <iostream><br>using namespace std;<br><br>#include <stdio.h></pre>
<pre>#define OTL_ODBC_MSSQL_2005 // Compile OTL 4/ODBC, MS SQL 2005<br>#define <a
href="otl3_compile.htm#OTL_UNICODE">OTL_UNICODE</a> // Enable Unicode OTL for 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_long_string.htm#otl_long_unicode_string">otl_long_unicode_string</a> f2(6000); // define long unicode string variable<br><br> <a
href="otl3_stream_class.htm">otl_stream</a> o;<br><br> o.set_lob_stream_mode(true); // set the "lob stream mode" flag<br> o.open(1, // buffer size has to be set to 1 for operations with CLOBs<br> "insert into test_tab values(:f1<int>,:f2<varchar_long>)",<br> // SQL statement<br> db // connect object<br> );<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> <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> int i,j;<br><br> for(i=1;i<=20;++i){<br> o<<i;<br> o<<lob; // Initialize otl_lob_stream by writing it<br> // into otl_stream.<br><br> for(j=0;j<5000;++j)<br> f2[j]=(unsigned short) '*'; // ASCII to Unicode.<br> f2[5000]= (unsigned short) '?'; // ASCII to Unicode<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 CLOB to be written.<br> <br> lob<<f2; // writing first chunk of the CLOB into lob<br><br> f2[2122]= (unsigned short) '?';<br> f2.set_len(2123); // setting the size of the second chunk<br><br> lob<<f2; // writing the second chunk of the CLOB into lob<br> lob.<a
href="otl3_lob_stream.htm">close</a>(); // closing the otl_lob_stream<br><br> }<br><br> db.commit(); // committing transaction.<br><br>}<br><br>void select()<br>{ <br> <a
href="otl3_long_string.htmotl_long_unicode_string">otl_long_unicode_string</a> f2(6000); // define Unicode long string variable<br><br> <a
href="otl3_stream_class.htm">otl_stream</a> i;<br> i.set_lob_stream_mode(true); // set the "lob stream mode" flag<br> i.open(1, // buffer size needs to be set to 1 in this case<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> <br> int f1;<br> <a
href="otl3_lob_stream.htm">otl_lob_stream</a> lob; // Stream for reading CLOB<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>>lob; // initializing CLOB stream by reading the CLOB 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 CLOB<br> ++n;<br> lob>>f2; // reading a chunk of CLOB<br> cout<<" chunk #"<<n;<br> cout<<", f2="<br> <<(char)f2[0] // Unicode to ASCII<br> <<(char)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>}</pre>
<pre>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@mssql"); // 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 nvarchar(max))"<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.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=5999<br> chunk #2, f2=*?, len=1125<br>f1=5<br> chunk #1, f2=**, len=5999<br> chunk #2, f2=*?, len=1125<br>f1=6<br> chunk #1, f2=**, len=5999<br> chunk #2, f2=*?, len=1125<br>f1=7<br> chunk #1, f2=**, len=5999<br> chunk #2, f2=*?, len=1125<br>f1=8<br> chunk #1, f2=**, len=5999<br> chunk #2, f2=*?, len=1125<br><br><hr
width="100%"></pre>
<center><a href="otl3_examples.htm">Examples</a> <a href="otl3.htm">Contents</a><a
href="home.htm">Go
Home</a></center>
<p>Copyright © 1996, 2008, Sergei Kuchin, email: <a
href="mailto:skuchin@aceweb.com">skuchin@aceweb.com</a>,
<a href="mailto:skuchin@gmail.com">skuchin@gmail.com
<script language="JavaScript">
<!-- hide from old browsers
var modDate = new Date(document.lastModified)
document.write("<i> Last Updated:</i> " + (modDate.getMonth()+1) + "/" +
modDate.getDate() + "/" + "0"+(modDate.getYear())%100+".");
//-->
</script></a>.
</p>
<p><i>Permission to use, copy, modify and redistribute this document
for
any purpose is hereby granted without fee, provided that the above
copyright
notice appear in all copies.</i>
</p>
</body>
</html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -