Macro merge_sql_query_as

macro_rules! merge_sql_query_as {
    ($dollar:tt($a:ident, $b:ident) as $as:ident) => { ... };
    ($dollar:tt@$suffix:ident, $a:ident, $b:ident) => { ... };
    ($dollar:tt@$suffix:ident, $a:ident, $b:ident $(, $c:ident)*) => { ... };
    ($dollar:tt($a:ident, $b:ident)) => { ... };
    ($dollar:tt($a:ident, $b:ident $(, $c:ident)*)) => { ... };
}