使用COracleADO构建稳健的数据库应用（c oracle ado）
使用C、Oracle、ADO构建稳健的数据库应用
在实际的工程应用中，使用C语言、Oracle数据库和ADO技术构建一个稳健的数据库应用是非常常见的。本文将介绍如何使用这三种技术构建一个可靠的数据库应用，并提供一些代码示例。
1.使用C语言
C语言是一种高效、简洁、可扩展的编程语言，因此在数据库应用中得到广泛应用。C语言支持底层的控制和操作系统级别的访问，这使得它成为数据库应用中常用的编程语言。下面是一些常用的C语言库和APIs：
1.1. ODBC API
ODBC API是Microsoft定义的一套数据库访问标准。ODBC API提供了连接数据库和查询数据的方法，可以在微软Windows平台上访问多种类型的数据库，包括Oracle、SQL Server和Access等。以下是ODBC API连接数据库的示例代码：
#include
#include
#include
int mn() {
SQLHENV henv;
SQLHDBC hdbc;
SQLRETURN ret;
// Allocate an environment handle
ret = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) {
printf(“Error allocating environment handle\n”);
return 1;
}
// Set environment attributes
ret = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, 0);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) {
printf(“Error setting environment attributes\n”);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 1;
}
// Allocate a connection handle
ret = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) {
printf(“Error allocating connection handle\n”);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 1;
}
// Connect to the database
ret = SQLConnect(hdbc, (SQLCHAR*) “YOUR_DSN_NAME”, SQL_NTS, (SQLCHAR*) “YOUR_USERNAME”, SQL_NTS, (SQLCHAR*) “YOUR_PASSWORD”, SQL_NTS);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) {
printf(“Error connecting to database\n”);
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 1;
}
// Disconnect from the database
ret = SQLDisconnect(hdbc);
if (ret != SQL_SUCCESS && ret != SQL_SUCCESS_WITH_INFO) {
printf(“Error disconnecting from database\n”);
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 1;
}
// Free the handles
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 0;
}
1.2. Oracle OCI
Oracle OCI（Oracle Call Interface）是一种用于连接Oracle数据库的C语言API。它支持多线程、预处理、批处理等功能。以下是OCI连接数据库的示例代码：
#include
#include
#include
#include
int mn(int argc, char *argv[]) {
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIServer *srvhp;
OCISession *usrhp;
sword status;
// Initialize the OCI environment
status = OCIEnvCreate(&envhp, OCI_DEFAULT, (void *)0, 0, 0, 0, (size_t)0, (void **)0);
if (status != OCI_SUCCESS) {
printf(“Error initializing OCI environment\n”);
return 1;
}
// Allocate an error handle
status = OCIHandleAlloc((void *)envhp, (void **)&errhp, OCI_HTYPE_ERROR, (size_t)0, (void **)0);
if (status != OCI_SUCCESS) {
printf(“Error allocating error handle\n”);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Allocate a server handle
status = OCIHandleAlloc((void *)envhp, (void **)&srvhp, OCI_HTYPE_SERVER, (size_t)0, (void **)0);
if (status != OCI_SUCCESS) {
printf(“Error allocating server handle\n”);
OCIHandleFree((void *)envhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Attach to the server
status = OCIServerAttach(srvhp, errhp, (text *)argv[1], strlen(argv[1]), 0);
if (status != OCI_SUCCESS) {
printf(“Error attaching to server\n”);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Allocate a service context handle
status = OCIHandleAlloc((void *)envhp, (void **)&svchp, OCI_HTYPE_SVCCTX, (size_t)0, (void **)0);
if (status != OCI_SUCCESS) {
printf(“Error allocating service context handle\n”);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Set the service context server handle
status = OCIAttrSet((void *)svchp, OCI_HTYPE_SVCCTX, (void *)srvhp, (ub4)0, OCI_ATTR_SERVER, (OCIError *)errhp);
if (status != OCI_SUCCESS) {
printf(“Error setting service context server handle\n”);
OCIHandleFree((void *)svchp, OCI_HTYPE_SVCCTX);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Allocate a user session handle
status = OCIHandleAlloc((void *)envhp, (void **)&usrhp, OCI_HTYPE_SESSION, (size_t)0, (void **)0);
if (status != OCI_SUCCESS) {
printf(“Error allocating user session handle\n”);
OCIHandleFree((void *)svchp, OCI_HTYPE_SVCCTX);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Set the user session username and password
status = OCIAttrSet((void *)usrhp, OCI_HTYPE_SESSION, (void *)argv[2], strlen(argv[2]), OCI_ATTR_USERNAME, errhp);
if (status != OCI_SUCCESS) {
printf(“Error setting user session username\n”);
OCIHandleFree((void *)usrhp, OCI_HTYPE_SESSION);
OCIHandleFree((void *)svchp, OCI_HTYPE_SVCCTX);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
status = OCIAttrSet((void *)usrhp, OCI_HTYPE_SESSION, (void *)argv[3], strlen(argv[3]), OCI_ATTR_PASSWORD, errhp);
if (status != OCI_SUCCESS) {
printf(“Error setting user session password\n”);
OCIHandleFree((void *)usrhp, OCI_HTYPE_SESSION);
OCIHandleFree((void *)svchp, OCI_HTYPE_SVCCTX);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((void *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((void *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((void *)envhp, OCI_HTYPE_ENV);
return 1;
}
// Start the user session
status = OCILogon(envhp, errhp, &svchp, usrhp, (text *)”UTF8″, (ub4)5, (text *)”
