C操作Oracle数据库实现图片存取（c# oracle 图片）
C操作Oracle数据库实现图片存取
在实际的开发中，我们经常需要在数据库中存储图片、音频、视频等大型二进制数据，而Oracle数据库是比较常用的关系型数据库之一。本文将介绍如何使用C语言操作Oracle数据库来实现图片的存储和读取。
1. 准备工作
在使用C语言操作Oracle数据库之前，需要安装Oracle客户端和Oracle ODBC驱动程序。安装完成后，需要设置一些环境变量：
– ORACLE_HOME：Oracle客户端的安装目录
– PATH：将Oracle客户端的bin目录添加到PATH环境变量中
– TNS_ADMIN：如果使用TNS描述符连接数据库，则需要设置该环境变量，值为TNS描述符所在的目录
2. 创建表结构
在Oracle数据库中，可以使用BLOB类型来存储大型二进制数据。下面是一个示例表结构：
CREATE TABLE image (
id NUMBER(10) NOT NULL,
name VARCHAR2(100) NOT NULL,
image_data BLOB,
CONSTRNT image_pk PRIMARY KEY (id)
);
3. 存储图片
下面是一个示例代码，用于将一张图片存储到Oracle数据库中：
#include
#include
const char* image_file = “test.jpg”;
const char* dsn = “ORACLE”;
int mn() {
OCIEnv* envhp;
OCIError* errhp;
OCISvcCtx* svchp;
OCIServer* srvhp;
OCISession* sesshp;
OCIStmt* stmthp;
OCILobLocator* lob = NULL;
FILE* fp;
int r, id;
// 初始化OCI环境
r = OCIEnvCreate(&envhp, OCI_DEFAULT, NULL, NULL, NULL, NULL, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIEnvCreate fled (%d)\n”, r);
return -1;
}
// 分配OCI错误句柄
r = OCIHandleAlloc(envhp, (void**)&errhp, OCI_HTYPE_ERROR, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (error) fled (%d)\n”, r);
return -1;
}
// 分配OCI服务上下文句柄
r = OCIHandleAlloc(envhp, (void**)&svchp, OCI_HTYPE_SVCCTX, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (service) fled (%d)\n”, r);
return -1;
}
// 分配OCI服务器句柄
r = OCIHandleAlloc(envhp, (void**)&srvhp, OCI_HTYPE_SERVER, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (server) fled (%d)\n”, r);
return -1;
}
// 分配OCI会话句柄
r = OCIHandleAlloc(envhp, (void**)&sesshp, OCI_HTYPE_SESSION, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (session) fled (%d)\n”, r);
return -1;
}
// 创建OCI服务器
r = OCIServerAttach(srvhp, errhp, (text*)dsn, strlen(dsn), OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (session) fled (%d)\n”, r);
return -1;
}
// 设置OCI服务上下文句柄属性
r = OCIAttrSet(svchp, OCI_HTYPE_SVCCTX, srvhp, 0, OCI_ATTR_SERVER, errhp);
if (r != OCI_SUCCESS) {
printf(“OCIAttrSet (server) fled (%d)\n”, r);
return -1;
}
// 设置OCI会话句柄属性
r = OCIAttrSet(sesshp, OCI_HTYPE_SESSION, (void*)”username”, strlen(“username”), OCI_ATTR_USERNAME, errhp);
if (r != OCI_SUCCESS) {
printf(“OCIAttrSet (username) fled (%d)\n”, r);
return -1;
}
r = OCIAttrSet(sesshp, OCI_HTYPE_SESSION, (void*)”password”, strlen(“password”), OCI_ATTR_PASSWORD, errhp);
if (r != OCI_SUCCESS) {
printf(“OCIAttrSet (password) fled (%d)\n”, r);
return -1;
}
// 启动OCI会话
r = OCISessionBegin(svchp, errhp, sesshp, OCI_CRED_RDBMS, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCISessionBegin fled (%d)\n”, r);
return -1;
}
// 设置OCI服务上下文句柄属性
r = OCIAttrSet(svchp, OCI_HTYPE_SVCCTX, sesshp, 0, OCI_ATTR_SESSION, errhp);
if (r != OCI_SUCCESS) {
printf(“OCIAttrSet (session) fled (%d)\n”, r);
return -1;
}
// 准备SQL语句
r = OCIHandleAlloc(envhp, (void**)&stmthp, OCI_HTYPE_STMT, 0, NULL);
if (r != OCI_SUCCESS) {
printf(“OCIHandleAlloc (statement) fled (%d)\n”, r);
return -1;
}
r = OCIStmtPrepare(stmthp, errhp, (text*)”INSERT INTO image (id, name, image_data) VALUES (:1, :2, :3)”, strlen(“INSERT INTO image (id, name, image_data) VALUES (:1, :2, :3)”), OCI_NTV_SYNTAX, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIStmtPrepare fled (%d)\n”, r);
return -1;
}
// 绑定变量
r = OCIBindByName(stmthp, (OCIBind**)&lob, errhp, (text*)”:3″, strlen(“:3”), (void**)NULL, 0, SQLT_BLOB, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIBindByName (lob) fled (%d)\n”, r);
return -1;
}
r = OCIBindByName(stmthp, (OCIBind**)&id, errhp, (text*)”:1″, strlen(“:1”), (void*)&id, sizeof(int), SQLT_INT, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIBindByName (id) fled (%d)\n”, r);
return -1;
}
r = OCIBindByName(stmthp, (OCIBind**)&name, errhp, (text*)”:2″, strlen(“:2”), (void*)name, sizeof(name), SQLT_STR, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIBindByName (name) fled (%d)\n”, r);
return -1;
}
// 执行SQL语句
r = OCIStmtExecute(svchp, stmthp, errhp, 1, 0, NULL, NULL, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCIStmtExecute fled (%d)\n”, r);
return -1;
}
// 读取图片数据
fp = fopen(image_file, “rb”);
if (fp == NULL) {
printf(“Fled to open file: %s\n”, image_file);
return -1;
}
fseek(fp, 0, SEEK_END);
int size = ftell(fp);
fseek(fp, 0, SEEK_SET);
char* data = malloc(size);
fread(data, size, 1, fp);
fclose(fp);
// 写入LOB
r = OCILobCreateTemporary(svchp, errhp, &lob, OCI_DEFAULT, SQLT_BLOB, OCI_ATTR_LOB_STORAGE);
if (r != OCI_SUCCESS) {
printf(“OCILobCreateTemporary fled (%d)\n”, r);
return -1;
}
r = OCILobWrite(svchp, errhp, lob, &size, 1, data, size, OCI_ONE_PIECE, NULL, NULL, 0, SQLCS_IMPLICIT);
if (r != OCI_SUCCESS) {
printf(“OCILobWrite fled (%d)\n”, r);
return -1;
}
// 提交事务
r = OCITransCommit(svchp, errhp, OCI_DEFAULT);
if (r != OCI_SUCCESS) {
printf(“OCITransCommit fled (%d)\n”, r);
return -1;
}
printf(“Image has been saved to database.\n”);
// 释放资源
OCIHandleFree(lob, OCI_HTYPE_LOB
