Teradata Update Table from Select Statement

问题:

Sorry if the title is unclear. Basically I'm trying to select certain records from multiple tables then update a certain column value for the returned records.

T-SQL Implementation

    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 

Oracle

    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'; 

I am tried doing the same thing in Teradata as I did in Oracle but I get the following error:

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.  

I looked online for the solution but had no luck.

回答1:

Have you tried the following syntax with Teradata:

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 

回答2:

I think that in this specific case, the below query will perform a little better since it needs one less join.

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 

文章来源: Teradata Update Table from Select Statement