selectRaw method
Adds aggregate columns to the selection without replacing existing columns.
Convenience method for adding COUNT, SUM, etc. to the query.
Implementation
QueryBuilder<T> selectRaw(String expression) {
if (_columns.length == 1 && _columns.first == '*') {
_columns = [RawExpression(expression)];
} else {
_columns.add(RawExpression(expression));
}
return this;
}