有关Hana Studio（SQL脚本）触发器的条件更新

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

我想要做的是使用SQL脚本在Hana Studio上编写一个触发器，以便在表1中的B列更新为特定值（比如100）时更新表2中的E列。表1中的行与第一列（ID）一起引用。

我写了以下代码：

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行上的TABLE1.COLUMN_B设置为100时，我希望代码在第1行将TABLE2.COLUMN_E更改为“我的新值”，但没有任何反应。任何人都可以指出我在这里做错了什么？

Answer 1

我想触发器代码中的UPDATE语句应该略有不同，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，我在创建触发器时会出现语法错误您可以验证吗？

Answer 2

菜鸟错了。我希望column_e值在column_b的值更改时更改，但我实际上是在跟踪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;

它工作了！