Oracle：根据外部参数true或false选择结果

编程问答 2022-06-10

问题描述

我有以下两个表TestCustomer和Testemail。我想基于TestCustomer上的email_stat和外部布尔参数“ noFlag”检索emailAddress，email_stat。如果noFlag为“ true”，则从 Testemail 表和与customer_id关联的email_stat TestCustomer ，否则只能获得“ A”。任何帮助。

create table Testemail(emai_id varchar(18),emailaddress varchar(20))

create table TestCustomer(customer_id varchar(18),emai_id varchar(18),email_stat char(1))

Insert Into Testemail(emai_id,emailaddress)values('12345','[email protected]');
Insert Into Testemail(emai_id,emailaddress)values('123456','[email protected]');
Insert Into Testemail(emai_id,emailaddress)values('123457','[email protected]');

Insert Into TestCustomer(customer_id,emai_id,email_stat)values('223459','12345','A');
Insert Into TestCustomer(customer_id,email_stat)values('223458','123456','I');
Insert Into TestCustomer(customer_id,'123457','A');

预期输入：

customer_id = 223458和noFlag ='true'

预期产量

enter image description here

预期输入：

customer_id = 223458和noFlag ='false'

预期产量

空结果。

解决方法

您要的是pl / sql代码吗？ 因为我不熟悉在没有pl \ sql功能的情况下在sql查询中获取外部参数的方法...

,

您可以创建一个虚拟列以将其标记为“ true”或“ false”：

1. Location    string `gorm:"where:location > 0" json:"location"`
2. Location    string `gorm:"where:location <> ''" json:"location"`
3. Location    string `gorm:"check: location > 0" json:"location"`
4. Location    string `gorm:"check: location <> '' " json:"location"`
5. Location    string `gorm:"check: location <> "" " json:"location"`

查询1： 

create table TestCustomer(customer_id varchar(18),emai_id varchar(18),email_stat char(1),noflag as (decode(email_stat,'I','true','false')));

enter image description here

查询2： 

select tc.customer_id,email_stat,te.emailaddress from TestCustomer tc join TestEmail te on tc.emai_id = te.emai_id where tc.customer_id=223458 and tc.noflag='true';

enter image description here

演示： https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=6291bf905c3387ff07e0ff145013afee


替代解决方案：

  1. 表结构不变
  2. 使用noflag列创建视图

数据库视图：

select tc.customer_id,te.emailaddress from TestCustomer tc join TestEmail te on tc.emai_id = te.emai_id where tc.customer_id=223458 and tc.noflag='false';

查询：

CREATE OR REPLACE VIEW vw_email AS
SELECT tc.customer_id,tc.email_stat,te.emailaddress,decode(tc.email_stat,'false') as noflag 
  FROM TestCustomer tc 
  JOIN TestEmail te on tc.emai_id = te.emai_id;

演示：

SELECT customer_id,emailaddress FROM vw_email WHERE customer_id=223458 AND noflag='true';
oracleoracle10goracle11gsqlsql