方式探究Oracle数据库的几种连接方式（oracle 几种连接）

Oracle数据库是一款非常流行的关系型数据库，它具有卓越的性能、可靠性和安全性，被广泛应用于企业级应用程序开发中。在Oracle数据库中，连接方式是重要的概念之一，通过不同的连接方式，我们可以实现不同的应用场景和需求。本文将探究Oracle数据库的几种连接方式，并介绍它们的使用方法和特点。

1. JDBC连接方式

JDBC（Java Database Connectivity）是一种Java程序访问关系型数据库的标准技术，通过JDBC连接，我们可以在Java程序中访问Oracle数据库，并进行数据操作。在使用JDBC连接Oracle数据库时，需要使用Oracle提供的JDBC驱动程序。下面是一个简单的JDBC连接Oracle数据库的示例代码：

“`java

import java.sql.*;

public class DBConnect {

public static void mn(String[] args) {

Connection conn = null;

try {

//加载Oracle JDBC驱动程序

Class.forName(“oracle.jdbc.driver.OracleDriver”);

//建立连接

conn = DriverManager.getConnection(

“jdbc:oracle:thin:@localhost:1521:ORCL”,

“scott”,

“tiger”);

//执行查询

Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery(

“SELECT * FROM emp”);

//输出结果

while (rs.next()) {

System.out.println(rs.getString(“ename”));

}

} catch (SQLException e) {

e.printStackTrace();

} catch (ClassNotFoundException e) {

e.printStackTrace();

} finally {

try {

if (conn != null) {

conn.close();

}

} catch (SQLException e) {

e.printStackTrace();

}

}

}

}

在上面的代码中，我们首先加载Oracle JDBC驱动程序，然后通过DriverManager.getConnection()方法建立连接，最后使用Statement.executeQuery()方法执行查询，并通过ResultSet获取查询结果。

2. OCI连接方式

OCI（Oracle Call Interface）是Oracle数据库提供的一种本地（即C/C++）语言访问Oracle数据库的接口，通过OCI连接方式，我们可以在C/C++程序中访问Oracle数据库，并进行数据操作。OCI连接方式相比JDBC连接方式，具有更高的性能和更多的功能。下面是一个简单的OCI连接Oracle数据库的示例代码：

```c
#include 
#include 
#include 
int mn() {
  OCIEnv *envhp;
  OCIError *errhp;
  OCIServer *srvhp;
  OCISvcCtx *svchp;
  OCISession *authp;
  OCIStmt *stmthp;
  OCIDefine *defnp;
  OCIParam *parmp;
  OCIDateTime *datetime;
  OCINumber *number;
  sword status;
  ub2 dtype;
  ub2 dsize;
  ub2 drc;
  ub2 npos;
  ub2 nlen;
  ub1 nbuf[128];
  char errmsg[2048];

  //初始化OCI环境
  status = OCIInitialize(OCI_DEFAULT, 0, 0, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIInitialize fled!\n");
    exit(1);
  }
  //分配OCI环境句柄
  status = OCIEnvInit(&envhp, OCI_DEFAULT, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIEnvInit fled!\n");
    exit(1);
  }
  //创建OCI错误句柄
  status = OCIHandleAlloc(envhp, (void **)&errhp, OCI_HTYPE_ERROR, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIHandleAlloc fled!\n");
    exit(1);
  }
  //创建OCI服务器句柄
  status = OCIHandleAlloc(envhp, (void **)&srvhp, OCI_HTYPE_SERVER, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIHandleAlloc fled!\n");
    exit(1);
  }
  //创建OCI服务上下文句柄
  status = OCIHandleAlloc(envhp, (void **)&svchp, OCI_HTYPE_SVCCTX, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIHandleAlloc fled!\n");
    exit(1);
  }
  //连接到Oracle数据库
  status = OCIServerAttach(srvhp, errhp, "", strlen(""), OCI_DEFAULT);
  if (status != OCI_SUCCESS) {
    OCIErrorGet(errhp, 1, 0, &status, (OraText *)errmsg, sizeof(errmsg), OCI_HTYPE_ERROR);
    printf("OCIServerAttach fled: %s\n", errmsg);
    exit(1);
  }
  //设置服务上下文属性
  status = OCIAttrSet(svchp, OCI_HTYPE_SVCCTX, srvhp, 0, OCI_ATTR_SERVER, errhp);
  if (status != OCI_SUCCESS) {
    printf("OCIAttrSet fled!\n");
    exit(1);
  }
  //创建OCI会话句柄
  status = OCIHandleAlloc(envhp, (void **)&authp, OCI_HTYPE_SESSION, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIHandleAlloc fled!\n");
    exit(1);
  }
  //设置会话属性
  status = OCIAttrSet(authp, OCI_HTYPE_SESSION, "", strlen(""), OCI_ATTR_USERNAME, errhp);
  if (status != OCI_SUCCESS) {
    printf("OCIAttrSet fled!\n");
    exit(1);
  }
  status = OCIAttrSet(authp, OCI_HTYPE_SESSION, "", strlen(""), OCI_ATTR_PASSWORD, errhp);
  if (status != OCI_SUCCESS) {
    printf("OCIAttrSet fled!\n");
    exit(1);
  }
  //启动会话
  status = OCISessionBegin(svchp, errhp, authp, OCI_CRED_RDBMS, OCI_DEFAULT);
  if (status != OCI_SUCCESS) {
    OCIErrorGet(errhp, 1, 0, &status, (OraText *)errmsg, sizeof(errmsg), OCI_HTYPE_ERROR);
    printf("OCISessionBegin fled: %s\n", errmsg);
    exit(1);
  }
  //设置服务上下文属性
  status = OCIAttrSet(svchp, OCI_HTYPE_SVCCTX, authp, 0, OCI_ATTR_SESSION, errhp);
  if (status != OCI_SUCCESS) {
    printf("OCIAttrSet fled!\n");
    exit(1);
  }
  //准备SQL语句
  status = OCIHandleAlloc(envhp, (void **)&stmthp, OCI_HTYPE_STMT, 0, 0);
  if (status != OCI_SUCCESS) {
    printf("OCIHandleAlloc fled!\n");
    exit(1);
  }
  status = OCIStmtPrepare(stmthp, errhp, "", strlen(""), OCI_NTV_SYNTAX, OCI_DEFAULT);
  if (status != OCI_SUCCESS) {
    OCIErrorGet(errhp, 1, 0, &status, (OraText *)errmsg, sizeof(errmsg), OCI_HTYPE_ERROR);
    printf("OCIStmtPrepare fled: %s\n", errmsg);
    exit(1);
  }
  //执行SQL语句
  status = OCIStmtExecute(svchp, stmthp, errhp, 0, 0, 0, 0, OCI_DEFAULT);
  if (status != OCI_SUCCESS) {
    OCIErrorGet(errhp, 1, 0, &status, (OraText *)errmsg, sizeof(errmsg), OCI_HTYPE_ERROR);
    printf("OCIStmtExecute fled: %s\n", errmsg);
    exit(1);
  }
  //获取结果值
  status = OCIStmtFetch(stmthp, errhp, 1, OCI_FETCH_NEXT, OCI_DEFAULT);
  while (status == OCI_SUCCESS) {
    //获取列数
    status = OCIAttrGet(stmthp, OCI_HTYPE_STMT, (void *)&dtype, 0, OCI_ATTR_PARAM_COUNT, errhp);
    if (status != OCI_SUCCESS) {
      printf("OCIAttrGet fled!\n");
      exit(1);
    }
    //输出结果
    for (int i = 1; i 
      status = OCIParamGet(stmthp, OCI_HTYPE_STMT, errhp, (void **)&parmp, i);
      if (status != OCI_SUCCESS) {
        printf("OCIParamGet fled!\n");
        exit(1);
      }
      switch (dtype) {
        case SQLT_CHR:
          status = OCIDefineByPos(stmthp, &defnp, errhp, i, (void *)nbuf, sizeof(nbuf), SQLT_STR, 0, 0, 0, OCI_DEFAULT);
          if (status != OCI_SUCCESS) {
            printf("OCIDefineByPos fled!\n");