Question

我正在使用microsoft sql server和我学习sql的基础... 我有一张桌子，里面有患者姓名和他们的主要医生。我想检查一下医生不能成为超过4名患者的主要医生这是我尝试过的：

CREATE ASSERTION assertion12
(not exist(
select DOCTOR.SSN
from Patient, DOCTOR
where Patient.primaryDoctor_SSN = DOCTOR.SSN
group by DOCTOR.SSN
having count(primaryDoctor_SSN) >= 5
);

但我在第一行收到错误：＆＃34;找不到存储过程＆＃34; 。（实际上红线是＆＃34; CREATE＆＃34;并显示此消息）

我该怎么办？！我查了一些网站，我看到写作断言就像我做的那样，我不知道为什么会出现这个错误。

Answer 1

SQL Server不支持CREATE ASSERTION。

事实上，当前的SQL产品没有正确支持CREATE ASSERTION。 Sybase SQL Anywhere支持它，但据报道存在允许有时违反约束的问题。 Rdb在被DEC监督时显然支持它（显然在SQL标准的早期有影响力，可能是CREATE ASSERTION首先在标准中的原因）但该产品不再是。

STOP PRESS：according to their documentation，HyperSQL（HSQLDB）支持断言（虽然我想知道他们为什么不在their list of features上大喊大叫）。

参考 Does SQL Server 2008 support the CREATE ASSERTION syntax?

Answer 2

SQL Server不支持Create Assertion，您可以使用Check Constraint或Create Trigger作为：

IF OBJECT_ID ('assertion12','TR') IS NOT NULL
   DROP TRIGGER assertion12;
GO
-- This trigger prevents a row from being inserted in the Patients table
-- when current patient's primary doctor already has patients = 4 (max 4)


CREATE TRIGGER assertion12 ON Patient
AFTER INSERT
AS
IF EXISTS ( select count(P.primaryDoctor_SSN)
            from Patient P 
            JOIN inserted AS i 
            ON p.primaryDoctor_SSN = i.primaryDoctor_SSN 
            group by P.primaryDoctor_SSN
            having count(P.primaryDoctor_SSN) =4
          )
BEGIN
RAISERROR ('Primary Doctor Assigned to the Patient already has 4 patients.', 16, 1);
ROLLBACK TRANSACTION;
RETURN 
END;
GO

-- This statement attempts to insert a row into the Patient table
-- The AFTER INSERT trigger is fired and the INSERT transaction is rolled back.

INSERT INTO Patient values (5,1)
GO

DEMO

得到错误：在进行断言时“无法找到存储过程”

2 个答案: