C登錄mysql數據庫的代碼如下：

#include#include#include#includeint main(int argc, char *argv[]) {
MYSQL *conn;
MYSQL_RES *res;
MYSQL_ROW row;
char *server = "localhost";
char *user = "root";
char *password = "root123";
char *database = "test";
char *query = "select * from users";
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, query)) {
fprintf(stderr, "%s\n", mysql_error(conn));
exit(1);
}
res = mysql_use_result(conn);
while ((row = mysql_fetch_row(res)) != NULL) {
printf("%s %s\n", row[0], row[1]);
}
mysql_free_result(res);
mysql_close(conn);
return 0;
}

以上代碼演示了如何使用C語言連接到MySQL數據庫并執行查詢語句。