"如何使用C语言连接MySQL数据库？掌握基础技巧轻松实现访问"

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Incorporating MySQL operations into C involves first installing the MySQL C API library and then utilizing functions from the mysql.h header file for tasks like connection and querying. Below is a simple example:

#include <stdio.h> #include <mysql/mysql.h> int main() { MYSQL *conn; MYSQL_RES *res; MYSQL_ROW row; char *server = "localhost"; char *user = "your_username"; char *password = "your_password"; char *database = "your_database"; conn = mysql_init(NULL); if (!mysql_real_connect(conn, server, user, password, database, 0, NULL, 0)) { fprintf(stderr, "%s", mysql_error(conn)); exit(1); } if (mysql_query(conn, "SELECT * FROM your_table")) { fprintf(stderr, "%s", mysql_error(conn)); exit(1); } res = mysql_use_result(conn); while ((row = mysql_fetch_row(res)) != NULL) { printf("%s", row[0]); } mysql_free_result(res); mysql_close(conn); return 0; }

Basic Techniques for Operating MySQL in C

1. Installing the MySQL C API Library

Before starting to work with MySQL in C, it's necessary to install the MySQL C API library, which can be done using the following command:

sudo aptget install libmysqlclientdev

2. Including Header Files

In a C program, include the following header files:

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

3. Establishing Database Connection

Use the mysql_init() and mysql_real_connect() functions to establish a database connection:

MYSQL *conn;
conn = mysql_init(NULL);
if (!mysql_real_connect(conn, "localhost", "username", "password", "database", 0, NULL, 0)) {
    fprintf(stderr, "%s", mysql_error(conn));
    exit(1);
}

4. Executing SQL Queries

Use the mysql_query() function to execute SQL queries:

if (mysql_query(conn, "SELECT * FROM table_name")) {
    fprintf(stderr, "%s", mysql_error(conn));
    exit(1);
}

5. Handling Query Results

Utilize the mysql_store_result() and mysql_fetch_row() functions to handle query results:

MYSQL_RES *result = mysql_store_result(conn);
if (result == NULL) {
    fprintf(stderr, "%s", mysql_error(conn));
    exit(1);
}
int num_fields = mysql_num_fields(result);
MYSQL_ROW row;
while ((row = mysql_fetch_row(result))) {
    for (int i = 0; i < num_fields; i++) {
        printf("%s ", row[i] ? row[i] : "NULL");
    }
    printf("");
}

6. Releasing Resources

Free up resources using the mysql_free_result() and mysql_close() functions:

mysql_free_result(result);
mysql_close(conn);

7. Complete Example

Here's a complete example demonstrating how to connect to a MySQL database and execute a query using C:

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

int main() {
    MYSQL *conn;
    MYSQL_RES *result;
    MYSQL_ROW row;
    int num_fields;

    conn = mysql_init(NULL);
    if (!mysql_real_connect(conn, "localhost", "username", "password", "database", 0, NULL, 0)) {
        fprintf(stderr, "%s", mysql_error(conn));
        exit(1);
    }

    if (mysql_query(conn, "SELECT * FROM table_name")) {
        fprintf(stderr, "%s", mysql_error(conn));
        exit(1);
    }

    result = mysql_store_result(conn);
    if (result == NULL) {
        fprintf(stderr, "%s", mysql_error(conn));
        exit(1);
    }

    num_fields = mysql_num_fields(result);
    while ((row = mysql_fetch_row(result))) {
        for (int i = 0; i < num_fields; i++) {
            printf("%s ", row[i] ? row[i] : "NULL");
        }
        printf("");
    }

    mysql_free_result(result);
    mysql_close(conn);

    return 0;
}

By following these steps, you can operate MySQL in C and execute queries successfully.

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Don't forget to replace 'your_username', 'your_password', 'your_database', and 'your_table' with your actual credentials and table name.

Feel free to ask if you have any questions or need further assistance.

Thank you for reading!

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