Question

我如何为学生分配用户名，使用他们的首字母后跟增加的数字？我不确定我的数据库中有多少学生，我希望他们的用户名看起来像“例如AC001，JD003。而且，如果有类似的首字母，我希望用户名继续按顺序递增。例如“AC001”和“AC002”

Answer 1

您需要在BEFORE INSERT事件和序列上使用触发器来实现此目的。

我假设您的表格如下：

TABLE user
( userid     VARCHAR2(100) -- PRIMARY KEY COLUMN
, firstname VARCHAR2(100)
, lastname    VARCHAR2(100)
, .... -- Other columns
);

按如下方式创建序列：

CREATE SEQUENCE sq_userid;

您将userid列设置为null的行插入。

INSERT INTO user VALUES (null, 'Jack', 'Daniels', ....);

然后，您的触发器应如下所示：

CREATE OR REPLACE TRIGGER trg_user
BEFORE INSERT ON user
REFERENCING new AS new old AS old
FOR EACH ROW
BEGIN
    IF :new.userid IS NULL THEN
        :new.userid := UPPER(LEFT(firstname, 1))
                      || UPPER(LEFT(lastname, 1))
                      || TO_CHAR(sq_userid.nextval, '099');
    END IF;
END;
/

触发器将'JD001'作为此实例中userid的值。

有关详细信息，请Coding triggers，sequences和to_char。

Answer 2

我认为这也会奏效 1st创建序列user_seq;

insert into user values('user_name'||user_seq.nextval);

您可以根据自己的要求修改上述查询。

Answer 3

我摆弄了一个解决方案，但它在MySQL中。我相信你可以得到一般的想法并将其转换为Oracle（SQL Fiddle本身有一个Oracle 11g选项）：http://sqlfiddle.com/#!2/e8ed5/1

<强>架构：

CREATE TABLE ALPHA_ROLL (
  ALPHA1 CHAR(1),
  ALPHA2 CHAR(1),
  ROLL INTEGER,
  PRIMARY KEY(ALPHA1, ALPHA2)
  )//

CREATE TABLE user (
  USERID VARCHAR(5),
  FIRSTNAME VARCHAR(100),
  LASTNAME VARCHAR(100),
  PRIMARY KEY (USERID)
  )//

CREATE TRIGGER trg_user
BEFORE INSERT ON user
FOR EACH ROW
BEGIN
  SET @gen_user_id = 
    (SELECT CONCAT(ALPHA1,ALPHA2,LPAD((ROLL+1), 3, '0'))
    FROM ALPHA_ROLL
    WHERE ALPHA1 = UPPER(LEFT(NEW.firstname, 1))
    AND ALPHA2 = UPPER(LEFT(NEW.lastname, 1))
    LIMIT 1);

  IF (@gen_user_id IS NULL) THEN
    INSERT INTO ALPHA_ROLL (ALPHA1, ALPHA2, ROLL)
    VALUES (UPPER(LEFT(new.firstname, 1)), UPPER(LEFT(new.lastname, 1)), 1);
    SET @GEN_USER_ID =
      CONCAT(UPPER(LEFT(new.firstname, 1)),
             UPPER(LEFT(new.lastname, 1)),
             '001');
  ELSE
    UPDATE ALPHA_ROLL SET ROLL = ROLL + 1
    WHERE ALPHA1 = UPPER(LEFT(new.firstname, 1))
    AND ALPHA2 = UPPER(LEFT(new.lastname, 1));
  END IF;

  SET new.userid = @GEN_USER_ID;
END//

<强> SQL：

INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Johnnie', 'Walker');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Jason', 'Mraz');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Mariah', 'Carrie');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Justin', 'Morg');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Matthew', 'Congoman');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Jack', 'Waltson');
INSERT INTO USER (FIRSTNAME, LASTNAME) VALUES ('Jojo', 'Wonderful');

SELECT * FROM USER;
SELECT * FROM ALPHA_ROLL;

<强>结果：

USERID  FIRSTNAME LASTNAME
JM001   Jason     Mraz
JM002   Justin    Morg
JW001   Johnnie   Walker
JW002   Jack      Waltson
JW003   Jojo      Wonderful
MC001   Mariah    Carrie
MC002   Matthew   Congoman

ALPHA1  ALPHA2  ROLL
J       M       2
J       W       3
M       C       2

Oracle如何分配用户名

3 个答案: