mysql中的fetch

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

int main() {
    MYSQL *conn;
    MYSQL_STMT *stmt;
    MYSQL_BIND bind[1];
    MYSQL_RES *prepare_meta_result;
    MYSQL_BIND result_bind[1];
    int query_status;

    char *server = "localhost";
    char *user = "root";
    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\n", mysql_error(conn));
        exit(1);
    }

    stmt = mysql_stmt_init(conn);
    if (!stmt) {
        fprintf(stderr, "mysql_stmt_init(), out of memory\n");
        exit(0);
    }

    query_status = mysql_stmt_prepare(stmt, "SELECT column_name FROM table_name WHERE condition", strlen("SELECT column_name FROM table_name WHERE condition"));
    if (query_status != 0) {
        fprintf(stderr, "mysql_stmt_prepare() failed\n");
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(0);
    }

    mysql_stmt_execute(stmt);

    prepare_meta_result = mysql_stmt_result_metadata(stmt);
    if (!prepare_meta_result) {
        fprintf(stderr, "mysql_stmt_result_metadata(), failed\n");
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(0);
    }

    result_bind[0].buffer_type = MYSQL_TYPE_STRING;
    result_bind[0].buffer = (char *)malloc(255);
    result_bind[0].buffer_length = 255;

    if (mysql_stmt_bind_result(stmt, result_bind)) {
        fprintf(stderr, "mysql_stmt_bind_result() failed\n");
        fprintf(stderr, "%s\n", mysql_stmt_error(stmt));
        exit(0);
    }

    while (!mysql_stmt_fetch(stmt)) {
        printf("%s\n", (char *)result_bind[0].buffer);
    }

    mysql_stmt_free_result(stmt);
    mysql_stmt_close(stmt);
    mysql_close(conn);

    return 0;
}