摘要
本文详细记录了，使用VS2013，VC++ Windows Console 程序运行 OTL 一个示例代码 Example 185 （ http://otl.sourceforge.net/otl4_ex185.htm）的过程，希望能帮到首次接触OTL的朋友。
1. OTL简介
OTL 是 Oracle, Odbc and DB2-CLI Template Library 的缩写，是一个C++操控关系数据库的模板库，它目前几乎支持所有的当前各种主流数据库，例如Oracle, MS SQL Server, Sybase, Informix, MySQL, DB2, Interbase / Firebird, PostgreSQL, SQLite, SAP/DB, TimesTen, MS ACCESS等等。OTL中直接操作Oracle主要是通过Oracle提供的OCI接口进行，进行操作DB2数据库则是通过CLI接口来进行，至于MS的数据库和其它一些数据库，则OTL只提供了ODBC来操作的方式。当然Oracle和DB2也可以由OTL间接使用ODBC的方式来进行操纵。OTL最新版本为4.0，项目主页：http://otl.sourceforge.net/
优点：
a. 跨平台
b. 运行效率高，与C语言直接调用API相当
c. 开发效率高，起码比ADO.net使用起来更简单，更简洁
d. 部署容易，不需要ADO组件，不需要.net framework 等
缺点：
我不知道，所以我不说:)
2. OTL下载
从主页：http://otl.sourceforge.net/可以进入下载页面，使用OTL开发，只需要下载其一个头文件就可以了，下载下来的头文件名为：otlv4.h。在下载页面也同时提供了帮助文档和例子程序的下载。
3. 编译调试运行示例 Example 185
3.1 打开VS2013，新建一个VC++空白的Win32 Console Application工程，Solution name：OTL Example，Project Name： Example185_Unicode_NVarChar2_otl_refcur_stream，添加cpp文件，main.cpp， 将示例代码（http://otl.sourceforge.net/otl4_ex185.htm）拷贝到main.cpp中，就向这样
别着急编译，一大堆错误呢，接着往下看。
3.2 配置x64 Solution Platform
系统环境是 Windows 8.1 Pro，64-bitOperating System, x64-based processor。OracleClient 64-bit, Release 11.2.0.3.0。
所以必须，新建x64 SolutionPlatform
点击OK，然后将编译平台设置为x64
3.3 添加引用otlv4.h
在解决方案文件所在的目录下，新建文件夹OTL_Include，将下载下来的otlv4.h文件放入其中，然后在工程属性中，添加刚才新建的目录作为otlv4.h引用路径：
$(SolutionDir)\OTL_Include
3.4 添加引用oci.h和oci.lib
从Oracle的安装路径中，找到oci.h和oci.lib所在的文件夹，将文件夹oci其拷贝到解决方案所在文件夹下。
然后依次修改下面3个工程属性：
1) oci.h引用路径：$(SolutionDir)\oci\include
2) Oci.lib引用路径：$(SolutionDir)\oci\lib\msvc
3) 指定oci.lib依赖
4 其它编译错误
当遇到以下编译错误时：
1>main.cpp(26): error C4996: 'sprintf': This function orvariable may be unsafe. Consider using sprintf_s instead. To disabledeprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1> C:\Program Files (x86)\Microsoft Visual Studio12.0\VC\include\stdio.h(356) : see declaration of 'sprintf'
使用sprintf_s替换掉函数sprintf。
至此，编译应该通过了。
5. 修改连接字符串
从例子代码中，找到rlogon函数调用，修改其连接到测试数据库，例如，我的就修改如下：
db.rlogon("fmuser_syy/fm@10.86.0.7:1521/fmorcl"); // connectto Oracle
6. 运行效果
7. 示例工程下载
http://download.csdn.net/detail/sunyeyi/8515193
资源分分很贵的！所以附上完整源代码一份，你也可以不必去下载！
//
// http://otl.sourceforge.net/otl4_ex185.htm
#include <iostream>
using namespace std;
#include <stdio.h>
#define OTL_ORA8I // Compile OTL 4.0/OCI8i
#define OTL_UNICODE // Enable Unicode OTL for OCI8i
#include <otlv4.h> // include the OTL 4.0 header file
otl_connect db; // connect object
void insert()
// insert rows into table
{
otl_stream o(50, // buffer size
"insert into test_tab values(:f1<float>,:f2<char[31]>)",
// SQL statement
db // connect object
);
char tmp[32];
unsigned short tmp2[32]; // Null terminated Unicode character array.
for (int i = 1; i <= 100; ++i){
sprintf_s(tmp, "Name%d", i);
unsigned short* c2 = tmp2;
char* c1 = tmp;
// Unicode's first 128 characters are ASCII (0..127), so
// all is needed for converting ASCII into Unicode is as follows:
while (*c1){
*c2 = (unsigned char)*c1;
++c1; ++c2;
}
*c2 = 0; // target Unicode string is null terminated,
// only the null terminator is a two-byte character,
// not one-byte
o << (float)i;
o << (unsigned char*)tmp2;
// overloaded operator<<(const unsigned char*) in the case of Unicode
// OTL accepts a pointer to a Unicode character array.
// operator<<(const unsigned short*) wasn't overloaded
// in order to avoid ambiguity in C++ type casting.
}
}
void select()
{
otl_stream i(1, // buffer size
"begin "
" open :cur<refcur,out[50]> for "
// :cur is a bind variable name, refcur -- its type,
// out -- output parameter, 50 -- the buffer size when this
// reference cursor will be attached to otl_refcur_stream
" select * "
" from test_tab "
" where f1>=:f<int,in> and f1<=:f*2; "
"end;", // PL/SQL block returns a referenced cursor
db // connect object
);
// create select stream with referenced cursor
i.set_commit(0); // set stream "auto-commit" to OFF.
float f1;
unsigned short f2[32];
otl_refcur_stream s; // reference cursor stream for reading rows.
i << 8; // assigning :f = 8
i >> s; // initializing the refrence cursor stream with the output
// reference cursor.
while (!s.eof()){ // while not end-of-data
s >> f1;
s >> (unsigned char*)f2;
// overloaded operator>>(unsigned char*) in the case of Unicode
// OTL accepts a pointer to a Unicode chracter array.
// operator>>(unsigned short*) wasn't overloaded
// in order to avoid ambiguity in C++ type casting.
cout << "f1=" << f1 << ", f2=";
// Unicode's first 128 characters are ASCII, so in order
// to convert Unicode back to ASCII all is needed is
// as follows:
for (int j = 0; f2[j] != 0; ++j){
cout << (char)f2[j];
}
cout << endl;
}
s.close(); // closing the reference cursor
i << 4; // assigning :f = 4
i >> s;
while (!s.eof()){ // while not end-of-data
s >> f1;
s >> (unsigned char*)f2;
// overloaded operator>>(unsigned char*) in the case of Unicode
// OTL accepts a pointer to a Unicode chracter array.
// operator>>(unsigned short*) wasn't overloaded
// in order to avoid ambiguity in C++ type casting.
cout << "f1=" << f1 << ", f2=";
// Unicode's first 128 characters are ASCII, so in order
// to convert Unicode back to ASCII all is needed is
// as follows:
for (int j = 0; f2[j] != 0; ++j){
cout << (char)f2[j];
}
cout << endl;
}
// there is no need to explicitly calls s.close() since s's destructor
// will take care of closing the stream
}
int main()
{
otl_connect::otl_initialize(); // initialize OCI environment
try{
db.rlogon("fmuser_syy/fm@10.86.0.7:1521/fmorcl"); // connect to Oracle
otl_cursor::direct_exec
(
db,
"drop table test_tab",
otl_exception::disabled // disable OTL exceptions
); // drop table
otl_cursor::direct_exec
(
db,
"create table test_tab(f1 number, f2 nvarchar2(60))"
); // create table
db.set_character_set(SQLCS_NCHAR);
insert(); // insert records into table
select(); // select records from table
}
catch (otl_exception& 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;
}