Question

我对Oracle数据库SQL有疑问。

我的员工每个人都有一个项目，项目的结束日期取决于基于PTerm给他们的月数。我这样做是对的吗？

CREATE TABLE PROJECT ( P_ID VARCHAR ( 20 ) NOT NULL,
                   PNAME VARCHAR ( 100 ) NOT NULL,
                   PTERM VARCHAR ( 20 ),
                   PSTARTDATE DATE,
                   PENDDATE DATE,
                   CONSTRAINT PROJECT_PKEY PRIMARY KEY ( P_ID ),
                   CONSTRAINT PROJECT_PTERM CHECK
                       ( PTERM IN ('1 MONTH', '2 MONTH', '3 MONTH') ),
                   CONSTRAINT PROJECT_ENDDATE CHECK
                       ( PENDDATE = (PSTARTDATE + PTERM) ) );

Answer 1

好的，我刚刚看到你提到Oracle，所以我会尝试这个

 CREATE TABLE PROJECT (

P_ID          VARCHAR(20) not null,
PName         VARCHAR(100) not null,
PTerm         VARCHAR(20),
PStartDate    DATE,
PEndDate      DATE,
constraint project_Pkey primary key (P_ID),
constraint project_pterm CHECK ( PTERM IN 
                        ('1 MONTH', '2 MONTH', '3 MONTH')),
constraint project_enddate CHECK(PEndDate = (add_months(PStartDate, to_number(substr(pTerm, 1, 1)))))

);

我相信如果你有一个字段表示数字（10）而不是varchar，那么你可以使用这个字段而不是在varchar字段中进行所有这些substr和to_number转换

Answer 2

如果这是Oracle，那么我会这样做

CREATE TABLE PROJECT ( P_ID VARCHAR ( 20 ) NOT NULL,
                   PNAME VARCHAR ( 100 ) NOT NULL,
                   PTERM VARCHAR ( 20 ),
                   PSTARTDATE DATE,
                   PENDDATE DATE,
                   CONSTRAINT PROJECT_PKEY PRIMARY KEY ( P_ID ),
                   CONSTRAINT PROJECT_PTERM CHECK
                       ( PTERM IN ('1', '2', '3') ),
                   CONSTRAINT PROJECT_ENDDATE CHECK
                       ( PENDDATE = ADD_MONTHS(PSTARTDATE , PTERM) ) );

如果我尝试下面的插入，它们会失败，因为它严格地在开始日期添加了几个月并期望与结束相同。

INSERT INTO
      PROJECT
VALUES
      ( 1,
        'asb',
        2,
        SYSDATE,
        SYSDATE
        + 60 );
--ORA-02290: check constraint (PROJECT_ENDDATE) violated

INSERT INTO
      PROJECT
VALUES
      ( 1,
        'asb',
        2,
        SYSDATE,
        SYSDATE
        + 62 );
--ORA-02290: check constraint (PROJECT_ENDDATE) violated

INSERT INTO
      PROJECT
VALUES
      ( 1,
        'asb',
        2,
        SYSDATE,
        SYSDATE
        + 61 );  
-- 1 row inserted

在Oracle SQL中将EndDate添加为约束作为约束

2 个答案: