:sig
DValue mysql_query(MySQL* m, String q, StringMap params)

:params
m : pointer to an active MySQL connection struct
q : a string containing a MySQL query
params : optional, a list of query parameter keys and values
return value : a list of rows returned from executing the query

:see
>mysql
mysql_affected_rows

:content
Executes a MySQL query and returns the resulting data, if any.

`params` provides the query parameter values used by the statement. Use named `:name` placeholders only; positional `?` placeholders are rejected.

The result is returned as a `DValue`, which makes it easy to iterate through rows and read fields with the usual `DValue` accessors.

After an insert, update, or delete, use `mysql_affected_rows()` to inspect how many rows changed.

:example
MySQL* db = mysql_connect();
if(db != 0)
{
    DValue rows = mysql_query(db, "select 'ada@example.test' as email, 1 + 1 as total");
    String email = "none"; String total = "?";
    rows.each([&](DValue r, String key) { email = r["email"].to_string(); total = r["total"].to_string(); });
    print(email, " / total=", total, "\n");
    mysql_disconnect(db);
}
else print("(requires a reachable MySQL server)\n");
