【笔记】【Berkeley DB】初窥Berkeley DB

#include <stdio.h>
#include <stdlib.h>
#include <db.h>
#include <string.h>

int main(int argc, char* argv[]) {
    //declare
    DB_ENV *ptr_db_env;
    DB *ptr_db;
    DBT key, data;
    u_int32_t env_flags, db_flags;
    FILE *fptr_db_env_err_log, *fptr_db_err_log;
    int ret;
    int sel;
    int userid;
    char *username;
    username = (char*) malloc(100 * sizeof(char));

    //initial

    fptr_db_env_err_log = fopen("./db_env_err.log", "r+");

    if (NULL == fptr_db_env_err_log) {
        printf("Open Enviroment Log File Failed!
");
    } else {
        printf("Open Enviroment Log File Succeeded!
");
    }

    ret = db_env_create(&ptr_db_env, 0);
    if (0 != ret) {
        printf("Create DB Enviroment Failed!
");
    } else {
        printf("Create DB Enviroment Succeeded!
");
        ptr_db_env->set_errfile(ptr_db_env, fptr_db_env_err_log);
    }

    env_flags = DB_CREATE | DB_INIT_MPOOL;

    ret = ptr_db_env->open(ptr_db_env, "/tmp/dbs", env_flags, 0);
    if (0 != ret) {
        printf("Open DB Enviroment Failed!
");
    } else {
        printf("Open DB Enviroment Succeeded!
");
    }

    fptr_db_err_log = fopen("./db_err.log", "r+");
    if (NULL == fptr_db_err_log) {
        printf("Open DB Log File Failed!
");
    } else {
        printf("Open DB Log File Succeeded!
");
    }

    ret = db_create(&ptr_db, ptr_db_env, 0);
    if (0 != ret) {
        printf("Create DB Failed!
");
    } else {
        printf("Create DB Succeeded!
");
        ptr_db->set_errfile(ptr_db, fptr_db_err_log);
    }

    db_flags = DB_CREATE;
    ret = ptr_db->open(ptr_db, NULL, "user.db", NULL, DB_HASH, db_flags, 0);
    if (0 != ret) {
        printf("Open DB Failed!
");
    } else {
        printf("Open DB Succeeded!
");
    }

    //ui
    memset(&key, 0, sizeof(DBT));
    memset(&data, 0, sizeof(DBT));

    while (1) {
        printf("========Menu========
");
        printf("1:add
");
        printf("2:query
");
        printf("3:delete
");
        printf("4:quit
");
        printf("Your selection:");
        scanf("%d", &sel);

        switch (sel) {
        case 1:
            printf("Please input the key:");
            scanf("%d", &userid);
            printf("Please input the name:");
            scanf("%s", username);
            key.data = &userid;
            key.size = sizeof(int);
            data.data = username;
            data.size = strlen(username) + 1;
            ret = ptr_db->put(ptr_db, NULL, &key, &data, DB_NOOVERWRITE);
            if (DB_KEYEXIST == ret) {
                printf("DB Key already exist!
");
            } else {
                printf("Add Record Succeeded!
");
            }
            break;
        case 2:
            printf("Please input the key:");
            scanf("%d", &userid);
            key.data = &userid;
            key.size = sizeof(int);
            data.data = username;
            data.ulen = 100;
            data.flags = DB_DBT_USERMEM;
            ret = ptr_db->get(ptr_db, NULL, &key, &data, 0);
            if (DB_NOTFOUND == ret) {
                printf("User ID %d Not Exist!
", userid);
            } else {
                printf("User ID:%d
User Name:%s
", userid, username);
            }
            break;
        case 3:
            printf("Please input the key:");
            scanf("%d", &userid);
            key.data = &userid;
            key.size = sizeof(int);
            ptr_db->del(ptr_db, NULL, &key, 0);
            printf("You have delete user %d succeeded
", userid);
            break;
        case 4:
            goto finish;
            break;
        default:
            printf("Unkown selection.
");
            break;
        }
    }

    //clean
    finish: if (NULL != fptr_db_err_log) {
        fclose(fptr_db_err_log);
    }

    if (NULL != fptr_db_env_err_log) {
        fclose(fptr_db_env_err_log);
    }

    if (NULL != ptr_db) {
        ptr_db->close(ptr_db, 0);
    }

    if (NULL != ptr_db_env) {
        ptr_db_env->close(ptr_db_env, 0);
    }

    return ret;
}