有人告诉我针对以下情况提出解决方案。
我需要基于“ EmployeeID”返回“最后更新日期”和“最后更新者”列。该查询必须在父表和所有子表中搜索最新条目,并返回按ID分组的列。我正在寻找一种不使用UNION ALL来连接父表和子表的解决方案,并且要解决这样一种情况,即两个不同的用户可以在不同表的同一EmployeeID(外键或主键)上输入最新记录。
例如,Jim今天更新了Employee表的EmployeeID 1,Paul也更新了EmployeeID 1的Employee_Address表。基于该EmployeeID 1,有两条记录是今天的最后更新日期,由不同用户输入。
请参阅架构和联合所有脚本,在其中我无法弄清其中的“上次更新者”部分。
CREATE TABLE EMPLOYEE
(
EMPLOYEE_ID INT,
NAME VARCHAR(100),
LAST_UPDATED_BY VARCHAR(200),
LAST_UPDATED_DT DATE
)
CREATE TABLE EMPLOYEE_AWARD
(
AWARD_ID INT,
EMPLOYEE_ID INT,
AWARD_NAME VARCHAR(100),
LAST_UPDATED_BY VARCHAR(200),
LAST_UPDATED_DT DATE
)
CREATE TABLE EMPLOYEE_ADDRESS
(
ADDRESS_ID INT,
EMPLOYEE_ID INT,
"ADDRESS" VARCHAR(100),
LAST_UPDATED_BY VARCHAR(200),
LAST_UPDATED_DT DATE
)
INSERT INTO EMPLOYEE
VALUES (1,'Paul Smith', 'GomesR', '6/22/2015'),
(2,'Francis Jones', 'KellyR', '5/20/2013'),
(3,'Paul Bo', 'GomesR', '11/09/2015'),
(4,'Ed Li', 'TurnerR', '1/19/2012')
INSERT INTO EMPLOYEE_AWARD
VALUES (10,1,'Employee of the Month', 'GomesR', '6/22/2015'),
(20,3,'Employee of the Month', 'KellyR', '5/20/2013'),
(30,1,'Employee of the Quater', 'GomesR', '11/09/2015'),
(40,3,'Employee of the Month', 'TurnerR', '1/19/2012'),
(50,2,'Employee of the Month', 'KellyR', '11/11/2011')
INSERT INTO EMPLOYEE_ADDRESS
VALUES (100,1,'Address 1','GomesR', '6/25/2015'),
(200,2,'Address 2','TurnerR', '5/28/2015'),
(300,3,'Address 3','TurnerR', '11/20/2015'),
(400,4,'Address 4','GomesR', '6/14/2014')
SELECT D.EMPLOYEE_ID, Max(D.LAST_UPDATED_DT) LAST_UPDATED_DT--, D.LAST_UPDATED_BY
FROM EMPLOYEE A
INNER JOIN ( SELECT EMPLOYEE_ID, LAST_UPDATED_DT, LAST_UPDATED_BY
FROM EMPLOYEE
UNION ALL
SELECT EMPLOYEE_ID, LAST_UPDATED_DT, LAST_UPDATED_BY
FROM EMPLOYEE_AWARD
UNION ALL
SELECT EMPLOYEE_ID, LAST_UPDATED_DT, LAST_UPDATED_BY
FROM EMPLOYEE_ADDRESS
) AS D
ON A.EMPLOYEE_ID = D.EMPLOYEE_ID
GROUP BY D.EMPLOYEE_ID
如果在2个不同的表上2个不同的用户在同一天根据需要更新了一个雇员,则将为同一雇员返回2行。
select employee_id,
last_updated_dt,
last_updated_by
from (select x.*,
max(last_updated_dt) over(partition by employee_id) as max_last_updated_dt
from (select employee_id,
last_updated_dt,
last_updated_by
from employee
union all
select employee_id,
last_updated_dt,
last_updated_by
from employee_award
union all
select employee_id,
last_updated_dt,
last_updated_by
from employee_address) x) x
where last_updated_dt = max_last_updated_dt
小提琴:http ://sqlfiddle.com/#!3/a4503c/1/0
您不应该避免使用union all
。数据位于三个不同的表中,因此这是的适当应用union all
。
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