如何通过将一个表中的 id 与 bigquery 中另一表的多个列中的 id 连接来获取记录？

Question

I have two tables emp and prj. Columns and data types of tables are as follows Emp has EmpNo(INT), EmpITPrj(STR), EmpFinPrj(STR), EmpHRPrj(STR), EmpIntPrj(STR), EmpDate(STR) and prj has PrjID(STR), PrjStartDate(STR), PrjEndDate(STR). The goal is to display all records that match the condition prj.PrjID is in one of the columns of emp.EmpITPrj, emp.EmpFinPrj, emp.EmpHRPrj or emp.EmpIntPrj AND emp.Date falls on or between the prj.PrjStartDate, prj.PrjEndDate.

EmpNo   EmpITPrj    EmpFinPrj   EmpHRPrj    EmpIntPrj   Date
1         IT101       null        null         null     2019-09-01
2         null        Fin101      null         null     2001-06-05
3         null        Fin102      null         null     2005-11-25
4         null        null        null         Int501   2010-10-15
5         null        null        null         Int105   2019-01-10
6         null        null        null         Int444   2015-12-03
7         null        null        HR110        null     2012-08-19
8         IT101       null        null         null     2011-04-24
9         null        null        HR105        null     2005-02-09
10        IT102       null        null         null     2006-07-11



PrjID   PrjStartDate    PrjEndDate
Fin102  10/14/2005      12/14/2005
IT102   07/11/2006      10/30/2006
IT110   11/15/2010      01/31/2011
Int101  01/01/2015      03/31/2015
HR110   05/19/2012      08/19/2012
Int444  01/01/2015      03/01/2015

End Result:
EmpNo   EmpITPrj    EmpFinPrj   EmpHRPrj    EmpIntPrj   EmpDate     PrjID   PrjStartDate    PrjEndDate
3       null        Fin102      null        null        2005-11-25  Fin102  10/14/2005      12/14/2005
10      IT102       null        null        null        2006-07-11  IT102   07/11/2006      10/30/2006
7       null        null        HR110       null        2012-08-19  HR110   05/19/2012      08/19/2012

The current query I am trying doesn't yield any results. Can anyone suggest how should I proceed with this query?

SELECT
 *
FROM
  `bigquery-project-123.emp` AS t1,
  `bigquery-project-123.prj` t2
WHERE
  (t1.EmpITPrj = t2.PrjID
    OR t1.EmpFinPrj = t2.PrjID
    OR t1.EmpHRPrj = t2.PrjID
    OR t1.EmpIntPrj = t2.PrjID
  AND SAFE.PARSE_DATE("%Y%m%d", t1.Date) >= SAFE.PARSE_DATE("%Y%m%d",t2.PrjStartDate)
    AND SAFE.PARSE_DATE("%Y%m%d", t1.Date) <= SAFE.PARSE_DATE("%Y%m%d",t2.PrjEndDate)

Answer 1

Below is for BigQuery Standard SQL

#standardSQL
WITH `bigquery-project-123.emp` AS (
  SELECT 1 EmpNo, 'IT101' EmpITPrj, NULL EmpFinPrj, NULL EmpHRPrj, NULL EmpIntPrj, '2019-09-01' EmpDate union all
  SELECT 2, NULL, 'Fin101', NULL, NULL, '2001-06-05' union all
  SELECT 3, NULL, 'Fin102', NULL, NULL, '2005-11-25' union all
  SELECT 4, NULL, NULL, NULL, 'Int501', '2010-10-15' union all
  SELECT 5, NULL, NULL, NULL, 'Int105', '2019-01-10' union all
  SELECT 6, NULL, NULL, NULL, 'Int444', '2015-12-03' union all
  SELECT 7, NULL, NULL, 'HR110', NULL, '2012-08-19' union all
  SELECT 8, 'IT101', NULL, NULL, NULL, '2011-04-24' union all
  SELECT 9, NULL, NULL, 'HR105', NULL, '2005-02-09' union all
  SELECT 10, 'IT102', NULL, NULL, NULL, '2006-07-11' 
), `bigquery-project-123.prj` AS (
  SELECT 'Fin102' PrjID, '10/14/2005' PrjStartDate, '12/14/2005' PrjEndDate union all
  SELECT 'IT102', '07/11/2006', '10/30/2006' union all
  SELECT 'IT110', '11/15/2010', '01/31/2011' union all
  SELECT 'Int101', '01/01/2015', '03/31/2015' union all
  SELECT 'HR110', '05/19/2012', '08/19/2012' union all
  SELECT 'Int444', '01/01/2015', '03/01/2015' 
)
SELECT *
FROM `bigquery-project-123.emp` AS t1
JOIN `bigquery-project-123.prj` t2 
ON t2.PrjID IN (t1.EmpITPrj,t1.EmpFinPrj,t1.EmpHRPrj,t1.EmpIntPrj)
AND SAFE.PARSE_DATE("%Y-%m-%d", t1.EmpDate) BETWEEN 
SAFE.PARSE_DATE("%m/%d/%Y",t2.PrjStartDate) AND SAFE.PARSE_DATE("%m/%d/%Y",t2.PrjEndDate) 

with result

Row EmpNo   EmpITPrj    EmpFinPrj   EmpHRPrj    EmpIntPrj   EmpDate     PrjID   PrjStartDate    PrjEndDate   
1   3       null        Fin102      null        null        2005-11-25  Fin102  10/14/2005      12/14/2005   
2   7       null        null        HR110       null        2012-08-19  HR110   05/19/2012      08/19/2012   
3   10      IT102       null        null        null        2006-07-11  IT102   07/11/2006      10/30/2006   

Answer 2

group your or conditions into 1. I suggest to use newer way of joining a table.

SELECT
 *
FROM
  `bigquery-project-123.emp` AS t1
LEFT JOIN `bigquery-project-123.prj` t2
    ON (t1.EmpITPrj = t2.PrjID
        OR t1.EmpFinPrj = t2.PrjID
        OR t1.EmpHRPrj = t2.PrjID
        OR t1.EmpIntPrj = t2.PrjID)
WHERE 
  SAFE.PARSE_DATE("%Y%m%d", t1.Date) >= SAFE.PARSE_DATE("%Y%m%d",t2.PrjStartDate)
    AND SAFE.PARSE_DATE("%Y%m%d", t1.Date) <= SAFE.PARSE_DATE("%Y%m%d",t2.PrjEndDate)