Oracle C语言开发实体类之旅（oracle c 实体类）
Oracle C语言开发实体类之旅
Oracle是众所周知的企业级数据库管理系统，它为许多大型企业提供了可靠的数据存储和管理。C语言则是一种高效且广泛使用的编程语言，与Oracle数据库一起使用可以实现高效、可靠的数据操作和管理。在此篇文章中，我们将一起探索如何使用C语言开发实体类，以便更好地与Oracle进行交互。
实体类是指一种对象，它封装了与数据表相关的数据和方法。因此，实体类中的属性和方法可以直接映射到数据库中的表和列上。在C语言中实现实体类可以使用结构体，它是一种组装数据项的数据类型。
下面是一个使用C语言实现Oracle实体类的示例：
“`c
#include
#include
#include
#include
/* 定义实体类 */
typedef struct {
int id; /*实体ID */
char name[50]; /*实体名称*/
char desc[256]; /*实体描述信息*/
} Entity;
/* 定义获取OCI错误信息的函数 */
void checkerr(OCIError *errhp, sword status) {
text errbuf[512];
sb4 errcode = 0;
OCIErrorGet((dvoid *) errhp, (ub4) 1, (text *) NULL, &errcode, errbuf,
(ub4) sizeof(errbuf), OCI_HTYPE_ERROR);
printf(“ERROR OCI-%d: %s\n”, errcode, errbuf);
exit(-1);
}
int mn(int argc, char **argv)
{
OCIEnv *envhp; /* 环境句柄 */
OCIServer *srvhp; /* 服务器句柄 */
OCIError *errhp; /* 错误句柄 */
OCISession *authp; /* 会话句柄 */
OCIStmt *stmthp; /* 语句句柄 */
OCIBind *bndp; /* 绑定句柄 */
OCIDefine *defp; /* 定义句柄 */
sword status; /* 状态变量 */
Entity myentity, myentity_read;
/* 初始化Oracle环境 */
OCIEnvCreate(&envhp, OCI_DEFAULT, (dvoid *) 0,
(dvoid * (*)(dvoid *, size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t)) 0,
(void (*)(dvoid *, dvoid *)) 0,
(size_t) 0, (dvoid **) 0);
/* 分配错误句柄 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR,
(size_t) 0, (dvoid **) 0);
/* 分配服务器句柄 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &srvhp, OCI_HTYPE_SERVER,
(size_t) 0, (dvoid **) 0);
/* 创建会话句柄 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &authp, OCI_HTYPE_SESSION,
(size_t) 0, (dvoid **) 0);
/* 分配语句句柄 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &stmthp, OCI_HTYPE_STMT,
(size_t) 0, (dvoid **) 0);
/* 连接到Oracle数据库 */
status = OCILogon(envhp, errhp, &authp, (OraText *) “username”,
strlen(“username”), (OraText *) “password”, strlen(“password”),
(OraText *) “dbname”, strlen(“dbname”));
if (status != OCI_SUCCESS) {
checkerr(errhp, status);
}
/* 准备SQL语句 */
OCIStmtPrepare(stmthp, errhp, (OraText *) “INSERT INTO Entity “
“(id, name, description) VALUES (:id, :name, :desc)”,
strlen(“INSERT INTO Entity “
“(id, name, description) VALUES (:id, :name, :desc)”),
OCI_NTV_SYNTAX, OCI_DEFAULT);
/* 进行绑定 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &bndp,
OCI_HTYPE_BIND, (size_t) 0, (dvoid **) 0);
OCIBindByPos(stmthp, &bndp, errhp, 1, (dvoid *) &myentity.id,
sizeof(myentity.id), SQLT_INT, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
0, (ub4 *) 0, OCI_DEFAULT);
OCIBindByPos(stmthp, &bndp, errhp, 2, (dvoid *) myentity.name,
strlen(myentity.name) + 1, SQLT_STR, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
0, (ub4 *) 0, OCI_DEFAULT);
OCIBindByPos(stmthp, &bndp, errhp, 3, (dvoid *) myentity.desc,
strlen(myentity.desc) + 1, SQLT_STR, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
0, (ub4 *) 0, OCI_DEFAULT);
/* 插入实体 */
myentity.id = 1;
strcpy(myentity.name, “My Entity”);
strcpy(myentity.desc, “This is my entity”);
status = OCIStmtExecute(authp, stmthp, errhp, (ub4) 1, (ub4) 0,
(OCISnapshot *) 0, (OCISnapshot *) 0, OCI_DEFAULT);
if (status != OCI_SUCCESS) {
checkerr(errhp, status);
}
/* 准备SQL语句 */
OCIStmtPrepare(stmthp, errhp, (OraText *) “SELECT * FROM Entity WHERE id = :id”,
strlen(“SELECT * FROM Entity WHERE id = :id”), OCI_NTV_SYNTAX, OCI_DEFAULT);
/* 进行绑定 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &bndp,
OCI_HTYPE_BIND, (size_t) 0, (dvoid **) 0);
OCIBindByPos(stmthp, &bndp, errhp, 1, (dvoid *) &myentity_read.id,
sizeof(myentity_read.id), SQLT_INT, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
0, (ub4 *) 0, OCI_DEFAULT);
/* 定义结果 */
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &defp,
OCI_HTYPE_DEFINE, (size_t) 0, (dvoid **) 0);
OCIDefineByPos(stmthp, &defp, errhp, 1, (dvoid *) myentity_read.name,
sizeof(myentity_read.name), SQLT_STR, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
OCI_DEFAULT);
OCIDefineByPos(stmthp, &defp, errhp, 2, (dvoid *) myentity_read.desc,
sizeof(myentity_read.desc), SQLT_STR, (dvoid *) 0, (ub2 *) 0, (ub2 *) 0,
OCI_DEFAULT);
status = OCIStmtExecute(authp, stmthp, errhp, (ub4) 1, (ub4) 0,
(OCISnapshot *) 0, (OCISnapshot *) 0, OCI_DEFAULT);
if (status != OCI_SUCCESS) {
checkerr(errhp, status);
}
/* 打印读取到的实体信息 */
printf(“\n——————-\n”);
printf(“ID: %d\n”, myentity_read.id);
printf(“Name: %s\n”, myentity_read.name);
printf(“Desc: %s\n”, myentity_read.desc);
/* 释放句柄 */
OCILogoff(authp, errhp);
OCIHandleFree((dvoid *) envhp, OCI_HTYPE_SERVER);
OCIHandleFree((dvoid *) envhp, OCI_HTYPE_SESSION);
OCIHandleFree((dvoid *) envhp, OCI_HTYPE_STMT);
OCIHandleFree((dvoid *) envhp, OCI_HTYPE_ERROR);
OCIHandleFree((dvoid *) envhp, OCI_HTYPE_ENV);
return 0;
}
通过上述代码，我们定义了一个名为Entity的实体类，实体包含
