Trigger After Update ,error: Scalar subquery is only allowed to return a single row

Question

我需要解决我的问题。提前致谢。我使用 Derby DB。

我有一个 table，只有几列。我在更新后为我需要的特定列创建了触发器。当我尝试更新行中的列时出现此错误。

Error code 30000, SQL state 21000: Scalar subquery is only allowed to return a single row.

仅当我在主 table 中有两行或更多行时才会出现此错误。如果我在 table "accounts" 中只有一行，一切正常。

这是触发器的代码：（帐户是主要的 table，accounts_history 新的 table）

CREATE TRIGGER aft_update AFTER UPDATE of balance,date
           ON  accounts  

FOR EACH ROW MODE DB2SQL

insert into accounts_history   

(old_id,new_name,new_balance,new_date) values
            (

(select id from accounts),(select name from accounts),

(select balance from accounts),(select date from accounts) 
            );

Answer 1

标量子查询应该 return 最多一行和一列。

只需使用insert . . . select:

insert into accounts_history(old_id, new_name, new_balance, new_date)
    select id, name, balance, date
    from accounts;

Trigger After Update ,error: Scalar subquery is only allowed to return a single row

Trigger After Update ,error: Scalar subquery is only allowed to return a single row

java

database

derby

scalar-subquery