Question

我有两个示例表：

    TABLE1:
      ID    | COLUMN_B| COLUMN_C
   _________|_________|_________
       1    |    0    |    1
    ________|_________|_________
       2    |    0    |    1
    ________|_________|_________
       3    |    0    |    1


    TABLE2:
      ID    | COLUMN_E| COLUMN_F
    ________|_________|________
       1    |    Y    |    X
    ________|_________|_________
       2    |    Y    |    X
    ________|_________|_________
       3    |    Y    |    X

我想做的是，当表1中的B列更新为特定值（例如100）时，使用SQL脚本在Hana Studio上编写触发器以更新表2中的E列。表1中的行在表2中带有第一列（ID）引用。

我编写了以下代码：

create trigger "UPDATE_TABLES"
    after update of "COLUMN_B" on "TABLE1"
    referencing new row as new, old row as old
    for each row 
begin
    update "TABLE2"
    set "COLUMN_E" = 'my new value'
    where :old."COLUMN_B" = '100' and "TABLE1"."ID" = :old."ID";
end;

当我将第1行的TABLE1.COLUMN_B设置为100时，我希望代码将第1行的TABLE2.COLUMN_E更改为“我的新值”，但是什么也没有发生。有人可以指出我在这里究竟在做什么错吗？

Answer 1

我猜触发代码中的UPDATE语句应该稍有不同，如下所示

create trigger "UPDATE_TABLES"
    after update of "COLUMN_B" on "TABLE1"
    referencing new row as new, old row as old
    for each row 
begin
    update "TABLE2"
    set "COLUMN_E" = 'my new value'
    where :new."COLUMN_B" = '100' 
    and TABLE2.ID = :old."ID";
end;

否则，在创建触发器时出现语法错误您能验证一下吗？

Answer 2

菜鸟错误。我希望column_e值更改column_b中值的更改，但实际上我是在跟踪column_b中的旧值。更正为：

create trigger "UPDATE_TABLES"
    after update of "COLUMN_B" on "TABLE1"
    referencing new row as new, old row as old
    for each row 
begin
    update "TABLE2"
    set "COLUMN_E" = 'my new value'
    where :new."COLUMN_B" = '100' and "TABLE1"."ID" = :old."ID";
end;

成功了！

Hana Studio（SQL脚本）触发器上的条件更新

2 个答案: