Question

我有一张桌子：

Athlete：

Athlete_NO (PK) | Athlete_DOB |

和

Competes：

Athlete_NO (PFK) | Discipline_Code |

和

Discipline：

Discipline_Code (PK) | Discipline_Name |

我试图编写一个触发器，该触发器不允许为某些学科插入18岁以下的运动员。篮球必须是18岁以上

我正在使用Oracle SQL Developer

感谢任何帮助（ - ：

我面临的问题是关注＆＃34; IF＆＃34; 18岁以下某些学科的代码。

Answer 1

尝试这个，但尚未测试

CREATE OR REPLACE TRIGGER athlete_insert BEFORE
  INSERT ON ATHLETE FOR EACH ROW DECLARE athlete_too_young EXCEPTION;
  BEGIN
    IF ((new.athelt_Birthday BETWEEN new.athelt_Birthday(YEAR,-19, GETDATE()) AND new.athelt_Birthday(DAY,-365,GETDATE())) / 365.242 < 16) THEN
      RAISE athlete_too_young;
    END IF;
  EXCEPTION
  WHEN athlete_too_young THEN
    RAISE_APPLICATION_ERROR(-20000, 'Athlete must be older than 16');
  END;

Answer 2

您需要在所涉及的表上提供完整性约束的触发器，即Athlete和Competes。

为了使用触发器正确创建此验证，应创建一个过程以获取用户指定的锁，以便在多用户环境中正确地序列化验证。

PROCEDURE request_lock
  (p_lockname                     IN     VARCHAR2
  ,p_lockmode                     IN     INTEGER  DEFAULT dbms_lock.x_mode
  ,p_timeout                      IN     INTEGER  DEFAULT 60
  ,p_release_on_commit            IN     BOOLEAN  DEFAULT TRUE
  ,p_expiration_secs              IN     INTEGER  DEFAULT 600)
IS
  -- dbms_lock.allocate_unique issues implicit commit, so place in its own
  -- transaction so it does not affect the caller
  PRAGMA AUTONOMOUS_TRANSACTION;
  l_lockhandle                   VARCHAR2(128);
  l_return                       NUMBER;
BEGIN
  dbms_lock.allocate_unique
    (lockname                       => p_lockname
    ,lockhandle                     => p_lockhandle
    ,expiration_secs                => p_expiration_secs);
  l_return := dbms_lock.request
    (lockhandle                     => l_lockhandle
    ,lockmode                       => p_lockmode
    ,timeout                        => p_timeout
    ,release_on_commit              => p_release_on_commit);
  IF    (l_return not in (0,4)) THEN
    raise_application_error(-20001, 'dbms_lock.request Failed ' || l_return);
  END IF;
  -- Must COMMIT an autonomous transaction
  COMMIT;
END request_lock;

然后可以在每个表的触发器中使用此过程，例如

CREATE OR REPLACE TRIGGER competes_trg
AFTER INSERT OR UPDATE ON competes
FOR EACH ROW
DECLARE
  l_athlete_dob                  athlete.athlete_dob%TYPE; 
BEGIN
  request_lock('ATHLETE_AGE_' || :new.athlete_no);
  SELECT athelete_dob
  INTO l_athlete_dob
  FROM athlete
  WHERE athlete_no = :new.athlete_no;
  IF (  :new.discipline_code = 'BASKETBALL'
     AND (  l_athlete_dob IS NULL
         OR months_between(trunc(sysdate), l_athlete_dob)/12 < 18))
  THEN
    raise_application_error(-20000, 'Athlete must be 18 or over for Basketball');
  END IF;
END;

和

CREATE OR REPLACE TRIGGER athlete_trg
AFTER INSERT OR UPDATE ON athlete
FOR EACH ROW
DECLARE
  CURSOR csr_competes
  IS
  SELECT discipline_code
  FROM competes
  WHERE athlete_no = :new.athlete_no;
BEGIN
  request_lock('ATHLETE_AGE_' || :new.athlete_no);
  FOR r_compete IN csr_competes LOOP
    IF (  r_compete.discipline_code = 'BASKETBALL'
       AND (  :new.athlete_dob IS NULL
           OR months_between(trunc(sysdate), :new.athlete_dob)/12 < 18))
    THEN
      raise_application_error(-20000, 'Athlete must be 18 or over for Basketball');
    END IF;
  END IF;
END;

您可以扩展IF条件以检查不同学科的不同年龄。

SQL：在插入或更新之前的条件触发器

2 个答案: