Linux环境下C语言MySQL接口API：第一讲

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Table of Contents

创建数据库

create_db.c

编译：

运行与结果查看：

查看MySQL版本

version.c

编译运行：

显示一个数据库

mysql_test.c

连接主机上的数据库

connect.c

插入数据库、从数据库中删除

insertDelMySQL.c

从数据库中查询

searchMySQL.c

makefile

---

创建数据库

create_db.c

#include <mysql/my_global.h>
#include <mysql/mysql.h>
#include <stdio.h>

int main(int argc, char **argv)
{  
  MYSQL *con = mysql_init(NULL);

  if (con == NULL) 
  {
      fprintf(stderr, "%s\n", mysql_error(con));
      exit(1);
  }

  if (mysql_real_connect(con, "localhost", "root", "root ", 
          NULL, 0, NULL, 0) == NULL) 
  {
      fprintf(stderr, "error:%s\n", mysql_error(con));
      mysql_close(con);
      exit(1);
  }  

  if (mysql_query(con, "CREATE DATABASE testdb")) 
  {
      fprintf(stderr, "%s\n", mysql_error(con));
      mysql_close(con);
      exit(1);
  }

  mysql_close(con);
  exit(0);
}

编译：

gcc createdb.c `mysql_config --libs --cflags`

运行与结果查看：

mysql> show databases
    -> ;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| testdb             |
+--------------------+
5 rows in set (0.00 sec)

mysql> use testdb
Database changed
mysql> show tables;
Empty set (0.00 sec)

mysql> 

查看MySQL版本

version.c

#include <my_global.h>
#include <mysql.h>

int main(int argc, char **argv)
{
  printf("MySQL client version: %s\n", mysql_get_client_info());

  exit(0);
}

编译运行：

$ gcc -o a version.c `mysql_config --cflags --libs`
$ ./a
MySQL client version: 5.7.21

显示一个数据库

mysql_test.c

#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>

int main(int argc, char * argv[])
{
    MYSQL * conn;
    MYSQL_RES * res;
    MYSQL_ROW row;
    char server[] = "localhost";
    char user[] = "root";
    char password[] = "root ";
    char database[] = "testdb";
    
    conn = mysql_init(NULL);
    if (!mysql_real_connect(conn, server,user, password, database, 0, NULL, 0)) 
    {
        fprintf(stderr, "%s\n", mysql_error(conn));
        exit(1);
    }
    if (mysql_query(conn, "show tables")) 
    {
        fprintf(stderr, "%s\n", mysql_error(conn));
        exit(1);
    }
    
    res = mysql_use_result(conn);
    
    printf("MySQL Tables in mysql database:\n");
    
    while ((row = mysql_fetch_row(res)) != NULL)
    {
        printf("%s \n", row[0]);
    }
    
    mysql_free_result(res);
    mysql_close(conn);
    
    printf("finish! \n");
    
    return 0;
}

连接主机上的数据库

connect.c

/*************************************
 * Programming Date   :2018年3月31日
 * Programming Content:linux环境实现用C语言连接MySql数据库连接操作-编译时加-lmysqlclient
 * Author             :Sun YiJie
**************************************/
#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>

#define HOST_NAME   "localhost"
#define USER_NAME   "root"
#define PASSWORD    "root "
#define DATABASES   "testdb"

int main(int argc, char * argv[])
{
    MYSQL       mysql;                        //定义MYSQL结构体对象
    /*分配和初始化mysql对象: mysql_init()*/
    if (NULL == mysql_init(&mysql))     
    {
        printf("mysql_init(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    /*连接主机上的MYSQL数据库: mysql_real_connect()*/
    if (NULL == mysql_real_connect(
                &mysql,
                HOST_NAME,
                USER_NAME,
                PASSWORD,
                DATABASES,
                0,
                NULL,
                0
                 ))
    {
        printf("mysql_real_connect(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    printf("Connect to MySql successful!\n");
    /*关闭数据库*/
    mysql_close(&mysql);
    return 0;
}

插入数据库、从数据库中删除

insertDelMySQL.c

/*************************************
 * Programming Date   :2018年3月31日
 * Programming Content:linux环境实现用C语言插入和删除MySql数据库操作-编译时加-lmysqlclient
 * Author             :Sun YiJie
**************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mysql/mysql.h>

#define HOST_NAME   "localhost"
#define USER_NAME   "root"
#define PASSWORD    "root "
#define DATABASES   "testdb"

int main(int argc, char * argv[])
{
    MYSQL       mysql;
    MYSQL_RES   * res = NULL;
    MYSQL_ROW   row;
    char        * query_str = NULL;
    int rc = 0, i = 0, fields = 0;
    int         rows = 0;
    /*分配和初始化mysql对象: mysql_init()*/
    if (NULL == mysql_init(&mysql))     
    {
        printf("mysql_init(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    /*连接主机上的MYSQL数据库: mysql_real_connect()*/
    if (NULL == mysql_real_connect(
                &mysql,
                HOST_NAME,
                USER_NAME,
                PASSWORD,
                DATABASES,
                0,
                NULL,
                0
                 ))
    {
        printf("1-mysql_real_connect(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    printf("---->Connect to MySql successful!<----\n");
    query_str = "insert into information values('005', 'Jerry', 25)";
    /*执行插入请求*/
    rc = mysql_real_query(&mysql, query_str, strlen(query_str));
    if (0 != rc)
    {
        printf("2-mysql_real_query(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }  
    query_str = "delete from information where name = 'Tom'";
    /*执行删除请求*/
    rc = mysql_real_query(&mysql, query_str, strlen(query_str));
    if (0 != rc)
    {
        printf("3-mysql_real_query(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }      
    query_str = "select * from information";
    /*执行数据库指令: mysql_real_query()*/
    rc = mysql_real_query(&mysql, query_str, strlen(query_str));
    if (0 != rc)
    {
        printf("4-mysql_real_query(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    /*得到数据库结果集合：mysql_store_result()*/
    res = mysql_store_result(&mysql);
    if (NULL == res)
    {
        printf("mysql_store_result(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);       
    }
    /*统计数据库行的数量：mysql_num_rows()*/
    rows = mysql_num_rows(res);
    printf("This table has %d rows!\n", rows);
    /*统计数据库列的数量：mysql_num_fields()*/
    fields = mysql_num_fields(res);
    printf("This table has %d fields!\n", fields);
    /*打印每一行的元素*/
    while (row = (mysql_fetch_row(res)))
    {
        for (i = 0; i < fields; i++)
        {
            printf("%s\t", row[i]);
        }
        printf("\n");
    }
    /*释放数据库结果集和空间*/
    mysql_free_result(res);
    /*关闭数据库*/
    mysql_close(&mysql);
    return 0;
}

从数据库中查询

searchMySQL.c

/*************************************
 * Programming Date   :2018年3月31日
 * Programming Content:linux环境实现用C语言查询MySql数据库操作-编译时加-lmysqlclient
 * Author             :Sun YiJie
**************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mysql/mysql.h>

#define HOST_NAME   "localhost"
#define USER_NAME   "root"
#define PASSWORD    "root "
#define DATABASES   "testdb"

int main(int argc, char * argv[])
{
    MYSQL       mysql;
    MYSQL_RES   * res = NULL;
    MYSQL_ROW   row;
    char        * query_str = NULL;
    int rc = 0, i = 0, fields = 0;
    int         rows = 0;
    /*分配和初始化mysql对象: mysql_init()*/
    if (NULL == mysql_init(&mysql))     
    {
        printf("mysql_init(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    /*连接主机上的MYSQL数据库: mysql_real_connect()*/
    if (NULL == mysql_real_connect(
                &mysql,
                HOST_NAME,
                USER_NAME,
                PASSWORD,
                DATABASES,
                0,
                NULL,
                0
                 ))
    {
        printf("mysql_real_connect(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    printf("---->Connect to MySql successful!<----\n");
    query_str = "select * from information";
    /*执行数据库指令: mysql_real_query()*/
    rc = mysql_real_query(&mysql, query_str, strlen(query_str));
    if (0 != rc)
    {
        printf("mysql_real_query(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);
    }
    /*得到数据库结果集合：mysql_store_result()*/
    res = mysql_store_result(&mysql);
    if (NULL == res)
    {
        printf("mysql_store_result(): %s\n", mysql_error(&mysql));
        exit(EXIT_FAILURE);       
    }
    /*统计数据库行的数量：mysql_num_rows()*/
    rows = mysql_num_rows(res);
    printf("This table has %d rows!\n", rows);
    /*统计数据库列的数量：mysql_num_fields()*/
    fields = mysql_num_fields(res);
    printf("This table has %d fields!\n", fields);
    /*打印每一行的元素*/
    while (row = (mysql_fetch_row(res)))
    {
        for (i = 0; i < fields; i++)
        {
            printf("%s\t", row[i]);
        }
        printf("\n");
    }
    /*释放数据库结果集和空间*/
    mysql_free_result(res);    
    /*关闭数据库*/
    mysql_close(&mysql);
    return 0;
}

makefile

files=`ls`

all: connectMySQL insertDelMySQL mysql_test searchMySQL
	#@echo $(suffix $(files))
	@echo $(files)

%:%.c
	gcc -o $@ $< `mysql_config --libs --cflags`