Question

所以我有这两个表：

create table CURRENCY
(
     name VARCHAR2(40 CHAR) PRIMARY KEY,
     value NUMBER(6,2)
);

create table EXCHANGE_RATE
(
     currency1 references CURRENCY(name),
     currency2 references CURRENCY(name),
     price NUMBER(6,2),
     PRIMARY KEY(currency1, currency2)
);

每当我插入新的CURRENCY时，我都想在所有先前的EXCHANGE_RATES与新的CURRIENCIES之间创建新的INSERT INTO CURRENCY VALUES("EURO", 2.0)。假设我的桌子上只有一种货币：

INSERT INTO CURRENCY VALUES("DOLLAR", 1.0)

现在要插入一个新的

EXCHANGE_RATE

我的目标是插入"EURO", "DOLLAR", 2.0 "DOLLAR", "EURO", 0.5行：

AFTER INSERT OR UPDATE

最好的方法是什么？我尝试使用CREATE OR REPLACE TRIGGER new_currency AFTER INSERT OR UPDATE ON CURRENCY FOR EACH ROW BEGIN INSERT INTO EXCHANGE_RATE (currency1, currency2, price) SELECT name, :new.name, price/:new.price FROM CURRENCY; INSERT INTO EXCHANGE_RATE (currency1, currency2, price) SELECT :new.name, name, :new.price/price FROM CURRENCY; END; / 触发：

CURRENCY

但是它不起作用，因为我必须查询render() { const { form, errorMessage } = this.props; const { getFieldDecorator, setFieldsValue } = form; return ( <Form> <FormItem> {getFieldDecorator(`slider`, {})( <div> <Slider onAfterChange={wantedValues => setFieldsValue({ slider: wantedValues })} range /> </div>, )} </FormItem> </Form> ); } } export default Form.create({ onValuesChange(props, changedValues, allValues) { console.log('on change', allValues); },表，该表正在更新，而我最终得到的是ORA-04091。

正确的方法是什么？

Answer 1

您无法查询导致触发器内部触发的表。

如果我是您，我将考虑使用存储过程方法。只需将您的插入脚本移到过程中

CREATE PROCEDURE INS_CURRENCY (p_currency varchar2, p_price number) as
BEGIN
    INSERT INTO CURRENCY VALUES(p_currency , p_Price);

    INSERT INTO EXCHANGE_RATE (currency1, currency2, price)
    SELECT name, p_currency, price/p_price
    FROM CURRENCY
    WHERE NAME != p_current;

    INSERT INTO EXCHANGE_RATE (currency1, currency2, price)
    SELECT  p_currency, name, p_price/price
    FROM CURRENCY
    WHERE name != p_currency;
END;

如何在触发器中使用来自更新表的数据？

1 个答案: