谈谈数据库编程语言和其他编程语言的区别
发布网友
发布时间：2022-04-07 16:21
共2个回答
懂视网
时间：2022-04-07 20:43
执行SQL语句
int mysql_query(MYSQL *pmysql,const char *sql);
参数pmysql是连接到MySQL的指针。 参数sql是要执行的SQL语句。 成功返回0,失败返回非0。 插入数据例子int main(int arg, char *args[])
{
MYSQL *connection, mysql;
mysql_init(&mysql);
connection = mysql_real_connect(&mysql, "localhost", "dbuser", "dbuser", "db1",0,0,0);
if (connect == NULL)
{
printf(mysql_error(&mysql));
return EXIT_FAILURE;
}
int state = mysql_query(connection, "INSERT INTO table1 (NAME,SEX,AGE,CLASS) VALUES (‘HAHA‘,1,30,‘666‘)");
if (state != 0)
{
printf(mysql_error(connection));
return EXIT_FAILURE;
}
mysql_close(connection);
return EXIT_SUCCESS;
}
修改数据例子
int main(int arg, char *args[])
{
MYSQL *connection, mysql;
mysql_init(&mysql);
connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0);
if (connect == NULL)
{
printf(mysql_error(&mysql));
return EXIT_FAILURE;
}
int state = mysql_query(connection, "UPDATE table1 SET CLASS = ‘250‘ WHERE NAME = ‘HAHA‘");
if (state != 0)
{
printf(mysql_error(connection));
return EXIT_FAILURE;
}
mysql_close(connection);
return EXIT_SUCCESS;
}
删除数据例子
int main(int arg, char *args[])
{
MYSQL *connection, mysql;
mysql_init(&mysql);
connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0);
if (connect == NULL)
{
printf(mysql_error(&mysql));
return EXIT_FAILURE;
}
int state = mysql_query(connection, “DELETE FROM table1 WHERE NAME = ‘HAHA‘");
if (state != 0)
{
printf(mysql_error(connection));
return EXIT_FAILURE;
}
mysql_close(connection);
return EXIT_SUCCESS;
}
执行SELECT语句得到查询结果
MYSQL_RES *mysql_store_result(MYSQL *pmysql);
成功返回一个查询结果指针，查询无结果或者错误返回NULL。mysql_free_result(MYSQL_RES *res)
调用完mysql_store_result，一定要用mysql_free_result释放相关的资源。 查看查询结果MYSQL_ROW mysql_fetch_row(MYSQL_RES *result);
例子while(row = mysql_fetch_row(result)) != NULL)
{
printf(“name:%s,sex:%s,age:%s,class:%s ”,row[0], row[1], row[2],row[3]
}
尽管在表中age是数字，但mysql返回的只不过是以NULL结尾的字符串。 查看查询结果中的字段信息MYSQL_FIELD *mysql_fetch_field (MYSQL_RES *result);
例子while ((sqlField = mysql_fetch_field(result)) != NULL)
{
printf("%s ", sqlField->name);
}
执行SELECT例子1
int main(int arg, char *args[])
{
MYSQL *connection, mysql;
mysql_init(&mysql);
connection = mysql_real_connect(&mysql, "localhost", "dbuser1", "dbuser1", "db1",0,0,0);
if (connect == NULL)
{
printf(mysql_error(&mysql));
return EXIT_FAILURE;
}
int state = mysql_query(connection, "SELECT NAME,SEX,AGE,CLASS FROM table1");
if (state != 0)
{
printf(mysql_error(connection));
return EXIT_FAILURE;
}
MYSQL_RES *result = mysql_store_result(connection);
if (result == (MYSQL_RES *)NULL)
{
printf(mysql_error(connection));
return EXIT_FAILURE;
}
MYSQL_ROW row;
while((row = mysql_fetch_row(result)) != NULL)
{
printf("name %s, sex %s, age %s, class %s
",
row[0],row[1],row[2],row[3]);
}
mysql_free_result(result);
mysql_close(connection);
return EXIT_SUCCESS;
}
执行SELECT例子2
int main(int arg, char *args[])
{
if (arg < 5)
return 0;
MYSQL *connection, mysql;
mysql_init(&mysql);
connection = mysql_real_connect(&mysql, args[1], args[2], args[3], args[4],
0, 0, 0);
if (connection == NULL)
{
printf("%s
", mysql_error(&mysql));
return EXIT_FAILURE;
}
printf("success connect to mysql
");
int state = mysql_query(connection, "SET NAMES utf8");
char buf[1024];
while (1)
{
memset(buf, 0, sizeof(buf));
read(STDIN_FILENO, buf, sizeof(buf));
if (strncmp(buf, "exit", 4) == 0)
{
break;
}
state = mysql_query(connection, buf);
if (state != 0)
{
printf("%s
", mysql_error(connection));
}
MYSQL_RES *result = mysql_store_result(connection);
if (result == NULL)
{
printf("%s
", mysql_error(connection));
break;
}
MYSQL_FIELD *sqlField;
int iFieldCount = 0;
while ((sqlField = mysql_fetch_field(result)) != NULL)
{
printf("%s ", sqlField->name);
iFieldCount++;
}
printf("
");
MYSQL_ROW row;
while ((row = mysql_fetch_row(result)) != NULL)
{
int i;
for (i = 0; i < iFieldCount; i++)
{
printf("%s ", row[i]);
}
printf("
");
}
mysql_free_result(result);
}
mysql_close(connection);
return EXIT_SUCCESS;
}
断开连接
mysql_close(MYSQL *connect);
使用完数据库后要记得断开连接，释放相关资源。 复制去Google翻译翻译结果数据库编程
标签：
热心网友
时间：2022-04-07 17:51
2。 正如楼所说，matlab是由C++编的，但其实这两者已无其他相通之处。也许你会说学过C++学matlab会好学，但其实是只要学过 编程语言的，一般学其他语言都比较容易入手(相对性的说)，那只是思想上的相通(当然语言有一些相同之处，但本人觉得思想作用更是突出。
。。)总之你学 matlab or C++，那你也就学了一种编程思想，这东西是内在的、持久的，我觉得也是最重要的，一种语言不可能打天下，但有了这种思想，入手其他语言就很容易了，这也是为什么程序员都会很多种语言！
