Teradata 从 Select 语句更新表

Question

抱歉，如果标题不清楚。基本上我试图从多个表中选择某些记录，然后更新返回记录的某个列值。

T-SQL 实现

    UPDATE 
        CUSTOMERS
    SET
        LIKES_US = 'Y'
    FROM
        RESTAURANT REST INNER JOIN CUSTOMERS CUST ON REST.LINK_ID = CUST.LINK_ID
        WHERE
        REST.REST_TYPE = 'Diner' AND CUST.LIKES_US IS NULL

甲骨文

    UPDATE 
       (SELECT CUST.LIKES_US
        FROM CUSTOMERS CUST INNER JOIN RESTAURANT REST ON CUST.LINK_ID=REST.LINK_ID
        WHERE REST.REST_TYPE = 'Diner' AND CUST.LIKES_US IS NULL) NEW_CUST
    SET
        NEW_CUST.LIKES_US = 'Y';

我尝试在 Teradata 中执行与在 Oracle 中相同的操作，但出现以下错误：

Executed as Single statement.  Failed [3707 : 42000] Syntax error, expected something like a name or a Unicode delimited identifier or an 'UDFCALLNAME' keyword between the 'UPDATE' keyword and '('. 
Elapsed time = 00:00:00.003 

STATEMENT 1: Unknown failed. 

我在网上寻找解决方案，但没有运气。

Answer 1

您是否在 Teradata 中尝试过以下语法：

UPDATE CUSTOMERS C1
  FROM (SELECT C2.LINK_ID
          FROM CUSTOMERS C2
         INNER JOIN RESTAURANTS R2
            ON C2.LINK_ID = R2.LINK_ID
        WHERE R2.REST_TYPE = 'DINER'
          AND C2.LIKES_US IS NULL) D1
   SET LIKES_US = 'Y'
 WHERE C1.LINK_ID = C2.LINK_ID

Answer 2

我认为在这种特定情况下，下面的查询会执行得更好一些，因为它需要少一个连接。

UPDATE C
FROM CUSTOMERS  C, RESTAURANTS R
SET LIKES_US = 'Y'
WHERE 
C.LINK_ID = R.LINK_ID
AND R.REST_TYPE = 'DINER'
AND C.LIKES_US IS NULL

Answer 3

@罗布·帕勒

我认为我们不能使用这种语法（TD17 中的中断）

这个有效。

UPDATE CUSTOMERS
  FROM (SELECT C2.LINK_ID
          FROM CUSTOMERS C2
         INNER JOIN RESTAURANTS R2
            ON C2.LINK_ID = R2.LINK_ID
        WHERE R2.REST_TYPE = 'DINER'
          AND C2.LIKES_US IS NULL) D1
   SET LIKES_US = 'Y'
 WHERE CUSTOMERS.LINK_ID = D1.LINK_ID