toSQL method
Generates the SQL representation with proper quoting and aliasing.
Handles table.field notation by quoting each part separately. Adds AS clause if an alias is provided.
Returns the properly quoted field name with optional alias.
Example:
QField('name').toSQL(); // "`name`"
QField('users.email').toSQL(); // "`users`.`email`"
QField('count', as: 'total').toSQL(); // "`count` AS `total`"
Implementation
@override
String toSQL() {
return '*';
}