C语言与Oracle配合，实现自增发展（c oracle 自增）
C语言与Oracle配合，实现自增发展
随着互联网时代的到来，数据处理和管理变得越来越重要。作为支持大型企业级应用系统的关系型数据库管理系统，Oracle一直被广泛使用。而对于程序员来说，C语言也是必备的编程语言之一。那么，如何将C语言与Oracle配合，实现自增发展呢？下面就让我们一起来了解一下。
一、数据库连接
首先需要连接Oracle数据库，并且选择一个待处理的表。这里我们以一个学生信息表为例。示例的数据库表结构如下：
CREATE TABLE student_info (
id number primary key,
name varchar2(50),
age number,
gender varchar2(10),
department varchar2(50)
);
在C语言中，需要通过调用Oracle提供的API来连接到数据库。示例代码如下：
#include
#include
#include
void checkerr(OCIError *errhp, sword status)
{
text errbuf[512];
sb4 errcode;
OCIErrorGet((dvoid *)errhp, (ub4)1, (text *)NULL, &errcode,
errbuf, (ub4)sizeof(errbuf), OCI_HTYPE_ERROR);
printf(“Error – %.*s”, 512, errbuf);
exit(1);
}
int mn(void)
{
OCIEnv *envhp;
OCIError *errhp;
OCIServer *srvhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIParam *paramhp;
sword status;
OCIInitialize((ub4)OCI_OBJECT, (dvoid *)0,
(dvoid * (*)(dvoid *, size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t))0,
(void (*)(dvoid *, dvoid *)) 0 );
OCIEnvInit((OCIEnv **)&envhp, OCI_OBJECT, 0, 0);
OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR,
(size_t)0, (dvoid **)0);
OCIHandleAlloc((dvoid *)envhp, (dvoid **)&srvhp, OCI_HTYPE_SERVER,
(size_t)0, (dvoid **)0);
OCIServerAttach(srvhp, errhp, (text *)”dbhost:1521/dbname”, -1, OCI_DEFAULT);
OCIHandleAlloc((void *) envhp, (void **)&svchp, OCI_HTYPE_SVCCTX,
(size_t) 0, (dvoid **) 0);
OCIAttrSet((void *) svchp, OCI_HTYPE_SVCCTX, (void *) srvhp,
(ub4) 0, OCI_ATTR_SERVER, errhp);
OCIHandleAlloc((dvoid *)envhp, (dvoid **)&stmthp, OCI_HTYPE_STMT,
(size_t)0, (dvoid **)0);
status = OCIStmtPrepare(stmthp, errhp, (text *)”SELECT * FROM student_info”,
(ub4)strlen(“SELECT * FROM student_info”), OCI_NTV_SYNTAX, OCI_DEFAULT);
if (status != OCI_SUCCESS) {
checkerr(errhp, status);
}
OCIHandleFree((dvoid *)stmthp, OCI_HTYPE_STMT);
OCIHandleFree((dvoid *)svchp, OCI_HTYPE_SVCCTX);
OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
OCIHandleFree((dvoid *)srvhp, OCI_HTYPE_SERVER);
OCIHandleFree((dvoid *)errhp, OCI_HTYPE_ERROR);
OCIEnvTerminate((dvoid *)envhp, OCI_OBJECT);
return 0;
}
在上面的示例代码中，我们首先进行了Oracle环境初始化，然后依次创建了错误句柄、服务器句柄、服务上下文句柄、语句句柄，并通过OCIServerAttach函数连接到了指定的数据库。通过OCIStmtPrepare函数执行了一条SELECT语句，获取了数据库表中所有的记录。需要注意的是，执行完成之后需要逐个释放所有分配的句柄。
二、数据插入
接下来，我们需要往数据库表中插入新的记录。这需要使用INSERT语句。 示例如下：
status = OCIStmtPrepare(stmthp, errhp, (text *)”INSERT INTO student_info (id, name, age, gender, department) VALUES (:1, :2, :3, :4, :5)”,
(ub4)strlen(“INSERT INTO student_info (id, name, age, gender, department) VALUES (:1, :2, :3, :4, :5)”), OCI_NTV_SYNTAX, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)1,
(dvoid *)&id, (sb4)sizeof(id), SQLT_INT, (void *)&ind1, (ub2 *)&alen1,
(ub2 *)0, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)2,
(dvoid *)name, (sb4)sizeof(name), SQLT_STR, (void *)&ind2, (ub2 *)&alen2,
(ub2 *)0, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)3,
(dvoid *)&age, (sb4)sizeof(age), SQLT_INT, (void *)&ind3, (ub2 *)&alen3,
(ub2 *)0, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)4,
(dvoid *)gender, (sb4)sizeof(gender), SQLT_STR, (void *)&ind4, (ub2 *)&alen4,
(ub2 *)0, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)5,
(dvoid *)department, (sb4)sizeof(department), SQLT_STR, (void *)&ind5,
(ub2 *)&alen5, (ub2 *)0, OCI_DEFAULT);
ind1 = 1;
ind2 = 0;
ind3 = 1;
ind4 = 0;
ind5 = 0;
id = 1001;
strcpy(name, “张三”);
age = 18;
strcpy(gender, “男”);
strcpy(department, “计算机科学与技术”);
status = OCIStmtExecute(svchp, stmthp, errhp,
(ub4)1, (ub4)0, (CONST OCISnapshot *) NULL, (OCISnapshot *) NULL,
OCI_DEFAULT);
通过OCIDefineByPos函数，我们指定了每一个绑定变量的位置和类型。然后，我们定义了五个变量来存储插入的记录的值，并使用OCIStmtExecute函数执行SQL语句。在执行完成后，需要释放分配的句柄，以避免内存泄漏。
三、数据更新
如果需要对表中的记录进行更新，那么需要使用UPDATE语句。示例代码如下：
status = OCIStmtPrepare(stmthp, errhp, (text *)”UPDATE student_info SET age = :1 WHERE id = :2″,
(ub4)strlen(“UPDATE student_info SET age = :1 WHERE id = :2”), OCI_NTV_SYNTAX, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)1,
(dvoid *)&age, (sb4)sizeof(age), SQLT_INT, (void *)&ind1,
(ub2 *)&alen1, (ub2 *)0, OCI_DEFAULT);
status = OCIDefineByPos(stmthp, ¶mhp, errhp, (ub4)2,
(dvoid *)&id, (sb4)sizeof(id), SQLT_INT, (void *)&ind2,
(ub2 *)&alen2, (ub2 *)0, OCI_DEFAULT);
age = 20;
id = 1001;
ind1 = 1;
ind2 = 1;
status = OCIStmtExecute(svchp, stmthp, errhp,
(ub4)1, (ub4)0, (CONST OCISnapshot *) NULL, (OCISnapshot *) NULL,
OCI_DEFAULT);
通过OCIDefineByPos函数，我们指定了更新的条件和需要更新的值的位置和类型。我们定义了两个变量来存储待更新记录的值和ID，并通过OCIStmtExecute函数执行SQL语句。
结论
通过上面的示例代码和分析，我们可以看到，在C语言与Oracle配合下，
