连接多个表的多个列值

Question

我需要连接多个表中多个列的值

前

userid        username         answeredquestion1 answeredquestion2
1                aa                       1             1
2                bb                       1              0

我需要结果

userid          username        question name           response
1                 aa             answertoquestion1         1   
2                 bb             answertoquestion2         0

如果值为null，则不应从第一个表中复制数据

我使用了以下命令，但它不起作用

INSERT ALL
WHEN AnswerToQuestion1 > 0 --and userid not in  (Select Userid from b) --and AnswerToQuestion1 not in (Select AnswerToQuestion from b) 
THEN
INTO b (userid, username, AnswerToQuestion) VALUES (UserID, UserName, AnswerToQuestion1)
WHEN AnswerToQuestion2 > 0 --and userid not in  (Select Userid from b) --and AnswerToQuestion2 not in (Select AnswerToQuestion from b) 
THEN
INTO b (userid, username, AnswerToQuestion) VALUES (UserID, UserName, AnswerToQuestion2) 
WHEN AnswerToQuestion3 > 0 --and userid not in  (Select Userid from b) --and AnswerToQuestion3 not in (Select AnswerToQuestion from b) 
THEN
INTO b (userid, username, AnswerToQuestion) VALUES (UserID, UserName, AnswerToQuestion3) 
SELECT UserID, UserName, AnswerToQuestion1, AnswerToQuestion2, AnswerToQuestion3 
FROM a
where not exists (SELECT userid, ANSWERTOQUESTION  FROM b where b.userid=a.userid and 
a.ANSWERTOQUESTION2 = b.ANSWERTOQUESTION) 

（或）

insert into b 
(select userID,username,AnswerToQuestion2 as AnswerToQuestion from a  where 
union all
select userID,username,AnswerToQuestion1 as AnswerToQuestion from a)

这将重复数据，这意味着重复值重复

我需要满足的条件是需要检查第一个表中的 4 列和第二个表中的 3 列。 谁能给我建议解决方案

提前致谢

Answer 1

在 Oracle 中，您可以在 USING 子查询中使用 UNPIVOT 语句来使用 MERGE：

SQL Fiddle

Oracle 11g R2 架构设置：

CREATE TABLE A (
  userid            INTEGER,
  username          VARCHAR2(20),
  answeredquestion1 NUMBER(1,0),
  answeredquestion2 NUMBER(1,0)
);

INSERT INTO A
SELECT 1, 'aa', 1, 1 FROM DUAL UNION ALL
SELECT 2, 'bb', 1, 0 FROM DUAL;

CREATE TABLE B (
  userid        INTEGER,
  username      VARCHAR2(20),
  question_name VARCHAR2(20),
  response      NUMBER(1,0)
);

MERGE INTO B dst
USING (
  SELECT userid, username, question_name, response
  FROM   A
  UNPIVOT (
    response
    FOR question_name IN (
      answeredquestion1 AS 'answertoquestion1',
      answeredquestion2 AS 'answertoquestion2'
    )
  )
) src
ON ( src.userid = dst.userid AND src.question_name = dst.question_name )
WHEN NOT MATCHED THEN
  INSERT ( userid, username, question_name, response )
  VALUES ( src.userid, src.username, src.question_name, src.response );

查询 1：

SELECT *
FROM   B

Results：

| USERID | USERNAME |     QUESTION_NAME | RESPONSE |
|--------|----------|-------------------|----------|
|      2 |       bb | answertoquestion1 |        1 |
|      2 |       bb | answertoquestion2 |        0 |
|      1 |       aa | answertoquestion1 |        1 |
|      1 |       aa | answertoquestion2 |        1 |