sql - Oracle SQL 获取变量的子串作为新变量

Question

我有一个列，我想只使用前两个字符来创建一个新列。我会假设以下应该工作，但它抛出 FROM keyword not found where expected错误

SELECT *,
       SUBSTR(PHONE_NUMBER , 1,2) AS MY_PHONE_NUMBER
FROM PHONE_NOS;

试试看 here

Answer 1

为表别名并在语句中使用它:

SELECT p.*,
       SUBSTR(p.PHONE_NUMBER, 1, 2) AS MY_PHONE_NUMBER
FROM PHONE_NOS p;