c apimysql预处理语句

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

int main() {
    MYSQL *conn;
    MYSQL_STMT *stmt;
    MYSQL_BIND bind[1];
    char query[] = "SELECT * FROM users WHERE id = ?";
    int id = 1;

    // 连接数据库
    conn = mysql_init(NULL);
    if (!mysql_real_connect(conn, "localhost", "user", "password", "database", 0, NULL, 0)) {
        fprintf(stderr, "%s\n", mysql_error(conn));
        exit(1);
    }

    // 准备预处理语句
    stmt = mysql_stmt_init(conn);
    if (!mysql_stmt_prepare(stmt, query, strlen(query))) {
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(1);
    }

    // 绑定参数
    memset(bind, 0, sizeof(bind));
    bind[0].buffer_type = MYSQL_TYPE_LONG;
    bind[0].buffer = (char *)&id;
    bind[0].is_null = 0;
    bind[0].length = 0;

    if (mysql_stmt_bind_param(stmt, bind)) {
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(1);
    }

    // 执行预处理语句
    if (mysql_stmt_execute(stmt)) {
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(1);
    }

    // 处理结果集
    MYSQL_RES *result = mysql_stmt_result_metadata(stmt);
    if (result) {
        int num_fields = mysql_num_fields(result);
        MYSQL_FIELD *fields = mysql_fetch_fields(result);

        MYSQL_BIND result_bind[num_fields];
        memset(result_bind, 0, sizeof(result_bind));

        for (int i = 0; i < num_fields; i++) {
            result_bind[i].buffer_type = fields[i].type;
            result_bind[i].buffer = malloc(fields[i].length);
            result_bind[i].buffer_length = fields[i].length;
        }

        if (mysql_stmt_bind_result(stmt, result_bind)) {
            fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
            exit(1);
        }

        while (!mysql_stmt_fetch(stmt)) {
            for (int i = 0; i < num_fields; i++) {
                printf("%s ", *(char *)result_bind[i].buffer);
            }
            printf("\n");
        }

        for (int i = 0; i < num_fields; i++) {
            free(result_bind[i].buffer);
        }
    }

    // 清理资源
    mysql_stmt_close(stmt);
    mysql_close(conn);

    return 0;
}