Examples to explain how to use oracle c (tutorial)

Oracle C Tutorial

Oracle C is a complete development platform launched by Oracle for C language developers. It provides a series of tools and libraries so that developers can easily create applications in the Oracle database. Develop in C language without using other development tools. This tutorial will briefly introduce the main features of Oracle C and provide some practical usage methods.

1. Characteristics of Oracle C

1. Supports multiple platforms

Oracle C can be developed on a variety of different platforms, including Unix, Linux, Windows, etc. No matter which platform you use, you can develop and deploy your applications with Oracle C.

2. Provide rich C language libraries

Oracle C provides a large number of C language libraries, covering various fields, such as mathematics, string processing, file operations, etc. . These libraries are very powerful and can help developers solve many problems easily.

3. Provide efficient database access

Oracle C provides a set of efficient APIs to easily access the Oracle database. Developers can use these APIs to perform SQL queries, inserts, updates and other operations, as well as transaction management, data backup and other operations.

4. Has good scalability

Oracle C supports plug-in development and can provide developers with more scalability. Developers can develop their own plug-ins according to their own needs and integrate them with Oracle C. This plug-in development method greatly enhances the flexibility and scalability of Oracle C.

2. Use Oracle C for development

1. Install Oracle C

Before using Oracle C for development, we need to install it first. The installation of Oracle C is very simple. You only need to download the installation package and follow the installation wizard. After the installation is complete, you can set the path required by Oracle C in the system environment variable to use it in subsequent development.

2. Writing code

After you have installed Oracle C, you can start writing your own code. Since Oracle C provides rich C language libraries, you can make full use of these libraries to develop your applications.

The following is an example of using Oracle C to access the Oracle database:

include <stdio.h>
include <stdlib.h>
include <oci.h>
void report_error(OCIError *err)
{
char err_buf[512];
sb4 err_code = 0;
OCIErrorGet((dvoid*)err, 1, (text*)NULL, &err_code, (text*)err_buf, (ub4)sizeof(err_buf), OCI_HTYPE_ERROR);
printf("Oracle Error: %s\n", err_buf);
}
int main()
{
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIDefine *defhp;
OCIDescribe *dschp;
OCIParam *parmp;
OCIType *typ;
text *query = (text*)"SELECT * FROM emp";

// 初始化环境
OCIEnvCreate(&envhp, OCI_THREADED|OCI_OBJECT, 0, 0, 0, 0, 0, 0);

// 创建错误句柄
OCIHandleAlloc((dvoid*)envhp, (dvoid**)&errhp, (ub4)OCI_HTYPE_ERROR, (size_t)0, (dvoid**)0);

// 创建服务上下文句柄
OCIHandleAlloc((dvoid*)envhp, (dvoid**)&svchp, (ub4)OCI_HTYPE_SVCCTX, (size_t)0, (dvoid**)0);

// 建立数据库连接
OCIAttrSet((dvoid*)svchp, (ub4)OCI_HTYPE_SVCCTX, (dvoid*)"orcl", (ub4)strlen("orcl"), (ub4)OCI_ATTR_SERVER, errhp);

// 准备SQL语句
OCIHandleAlloc((dvoid*)envhp, (dvoid**)&stmthp, (ub4)OCI_HTYPE_STMT, (size_t)0, (dvoid**)0);
OCIStmtPrepare(stmthp, errhp, query, (ub4)strlen((const char*)query), (ub4)OCI_NTV_SYNTAX, (ub4)OCI_DEFAULT);

// 执行SQL查询
OCIStmtExecute(svchp, stmthp, errhp, (ub4)1, (ub4)0, (CONST OCISnapshot *)NULL, (OCISnapshot *)NULL, (ub4)OCI_DEFAULT);

// 获取查询结果
OCIParamGet(stmthp, OCI_HTYPE_STMT, errhp, (dvoid**)&parmp, 1);

// 打印查询结果
sword col_num;
OCIAttrGet(parmp, OCI_DTYPE_PARAM, &col_num, 0, OCI_ATTR_NUM_COLS, errhp);
printf("Query result:\n");
printf("=========================\n");
for(int i = 1; i <= col_num; i++) {
    char col_name[256];
    ub2 col_name_len;
    OCIParamGet(parmp, OCI_HTYPE_PARAM, errhp, (dvoid**)&dschp, i);
    OCIAttrGet(dschp, OCI_DTYPE_PARAM, &typ, 0, OCI_ATTR_TYPE_NAME, errhp);
    OCITypeGetName(envhp, errhp, typ, col_name, &col_name_len);
    printf("%s\t", col_name);
}
printf("\n");
for(int j = 0; j < col_num; j++) {
    int empno, salary;
    text ename[10], job[9];
    OCIDefine *def1 = (OCIDefine *) 0;
    OCIDefine *def2 = (OCIDefine *) 0;
    OCIDefine *def3 = (OCIDefine *) 0;
    OCIDefine *def4 = (OCIDefine *) 0;
    OCIDefine *def5 = (OCIDefine *) 0;
    OCIStmtFetch2(stmthp, errhp, 1, OCI_FETCH_NEXT, 0, OCI_DEFAULT);
    if(OCI_SUCCESS == OCIAttrGet(stmthp, OCI_HTYPE_STMT, (dvoid *)&defhp, j, OCI_ATTR_DESCRIBE_OUTPUT, errhp)) {
        OCITypeGetName(envhp, errhp, typ, col_name, &col_name_len);
        OCIHandleFree(defhp, OCI_HTYPE_DESCRIBE);
    }
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&def1, OCI_HTYPE_DEFINE, 0, (dvoid **)0);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&def2, OCI_HTYPE_DEFINE, 0, (dvoid **)0);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&def3, OCI_HTYPE_DEFINE, 0, (dvoid **)0);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&def4, OCI_HTYPE_DEFINE, 0, (dvoid **)0);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&def5, OCI_HTYPE_DEFINE, 0, (dvoid **)0);
    OCIStmtGetPieceInfo(stmthp, errhp, (dvoid **) &def5, &def1, &def2, &def3, &def4, j);
    OCIAttrGet(def1, OCI_HTYPE_DEFINE, &empno, 0, OCI_ATTR_DATA, errhp);
    OCIAttrGet(def2, OCI_HTYPE_DEFINE, ename, 0, OCI_ATTR_DATA, errhp);
    OCIAttrGet(def3, OCI_HTYPE_DEFINE, job, 0, OCI_ATTR_DATA, errhp);
    OCIAttrGet(def4, OCI_HTYPE_DEFINE, &salary, 0, OCI_ATTR_DATA, errhp);
    printf("%d\t%s\t%s\t%d\n", empno, ename, job, salary);
}

// 关闭查询句柄
OCIHandleFree((dvoid*)stmthp, (ub4)OCI_HTYPE_STMT);

// 关闭服务上下文句柄
OCIHandleFree((dvoid*)svchp, (ub4)OCI_HTYPE_SVCCTX);

// 关闭错误句柄
OCIHandleFree((dvoid*)errhp, (ub4)OCI_HTYPE_ERROR);

// 关闭环境句柄
OCIHandleFree((dvoid*)envhp, (ub4)OCI_HTYPE_ENV);

return 0;
}

The above code is a simple C language program that can connect to the Oracle database and execute queries. You can learn how to use Oracle C by reading the code and comments.

3. Summary

This tutorial briefly introduces the main features of Oracle C and provides an example of using Oracle C to access the Oracle database. Oracle C has a rich C language library, supports efficient database access, has good scalability and other characteristics, and is very suitable for C language developers to develop Oracle database. If you are developing an Oracle database application and want to do it in C, try Oracle C.

The above is the detailed content of Examples to explain how to use oracle c (tutorial). For more information, please follow other related articles on the PHP Chinese website!