I need a help with a small query.
Table A:- status and the contents of it are below.
status_id status_descrip
1 held
2 release
3 WIP
Table B:- Entry is another table which has some 30 fields. Out of which 2 fields are referring to Table A-> status table. For simplicity i am skipping other fields and jotting down only the fields related with status.
entry_id design_status stress_status
1 3 1
2 1 2
3 NULL 2
4 3 3
5 NULL 1
6 NULL NULL
7 NULL 2
I can't change the structure of Entry to split into 2 tables one as design_status and other as stress_status.
Now i want the entries from entry table replace the status with their descriptions. so the output will be
entry_id design_status_descrip stress_status_descrip
1 WIP held
2 held release
3 NULL release
4 WIP WIP.
5 NULL 开发者_运维问答 held
6 NULL NULL
7 NULL release
Thanks in advance!
EDIT:-
Question is edited with Entries.
Thankyou for all your responses!
and the query finally working for me is,
SELECT b.entry_id, design_status_descrip = d.status_descrip,
stress_status_descrip = s.status_descrip FROM entry AS b
LEFT OUTER JOIN status AS d ON b.design_status = d.status_id
LEFT OUTER JOIN status AS s ON b.stress_status = s.status_id
do let me know, if i can improve this query.
The simplest way would be to join against the status table twice. I've used INNER JOIN assuming that the design_status and stress_status columns in your schema have proper constraints. Edited for changed requirements.
DECLARE @status TABLE
(
status_id INT PRIMARY KEY,
status_descrip VARCHAR(32) NOT NULL UNIQUE
);
INSERT @status SELECT 1,'held' UNION SELECT 2,'release' UNION SELECT 3,'WIP';
DECLARE @b TABLE
(
entry_id INT PRIMARY KEY,
design_status INT,
stress_status INT
);
INSERT @b SELECT 1,3,1
UNION SELECT 2,1,2
UNION SELECT 3,NULL,2
UNION SELECT 4,3,3
UNION SELECT 5,NULL,1
UNION SELECT 6,NULL,NULL
UNION SELECT 7,NULL,2;
SELECT
b.entry_id,
design_status_descrip = d.status_descrip,
stress_status_descrip = s.status_descrip
FROM
@b AS b
LEFT OUTER JOIN @status AS d
ON b.design_status = d.status_id
LEFT OUTER JOIN @status AS s
ON b.stress_status = s.status_id;
just join twice to the status table
From
Entry e
Inner join status ds
On e. design_status_id = ds.status_id
Inner join status ss
On e.stress_status_id = ss.status_id
SELECT
e.entry_id,
s1.status_descrip as design_status_descrip,
s2.status_descrip as stress_status_descrip
FROM entry e, status s1, status s2
WHERE
e.design_status = s1.status_id
AND e.stress_status = s2.status_id
Couple of approaches, first is the most efficient.
SELECT
e.entry_id
, MAX(CASE WHEN e.design_status = s.status_id THEN s.status_descrip END) AS design_status_descrip
, MAX(CASE WHEN e.stress_status = s.status_id THEN s.status_descrip END) AS stress_status_descrip
FROM
dbo.[Entry] e
LEFT OUTER JOIN
dbo.[Status] s
ON s.status_id = e.design_status
OR s.status_id = e.stress_status
GROUP BY
entry_id
SELECT e.entry_id , ds.status_descrip AS design_status_descrip , ss.status_descrip AS stress_status_descrip FROM dbo.[Entry] e LEFT OUTER JOIN dbo.[status] ds ON ds.status_id = e.design_status LEFT OUTER JOIN dbo.[status] ss ON ss.status_id = e.stress_status
I notice you have NULL
's in your data, in which case ignore all the answers using INNER JOIN
as this will effectively filter out any row with a null in either column. Instead use a left join.
SELECT
e.entry_id,
ds.status_description,
ss.ststua_description
FROM entry e
LEFT JOIN status ds
ON e.design_status = ds.status_id
LEFT JOIN status ss
ON e.stress_status = ss.status_id
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