public static <T> SQLQuery<T> selectFrom(RelationalPath<T> expr) {
        return select(expr).from(expr);
    }
Create a new detached SQLQuery instance with the given projection

@param expr query source and projection
@param <T>
@return select(expr).from(expr)
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java