Sql query to get data which has same id in multiple rows with different state

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Not an expert in SQL yet. :) Let us assume we have the below table:

Table A (id1 and id2 are primary keys)

Columns:

id1      id2   status
 1        1    true // values entry
 1        2    false
 3        4    true
 3        5    false

Now while getting data for id1, I want to make sure the status is true in both the rows. What would be the efficient way to get this?

In the example, I want to return empty result since id1 has false state in at least 1 entry.

SQL

Select id1 from A where status = true

What I have tried:

I tried, however it does not check if same id is available in other rows.

SQL

SELECT DISTINCT id1 FROM A WHERE status = 1

Do we need to add sub query for this then using IN or Exists? Will really appreciate it if any of you guys point me in the right direction. :)

SQL

SELECT DISTINCT id1 FROM A WHERE status = 1 and not exist in (SELECT DISTINCT id1 FROM A WHERE status = 0)

??

Posted 30-Aug-23 19:51pm

Member 11314626

Updated 13-Sep-23 3:54am

Deeksha Shenoy

v5

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2 solutions

Solution 1

DISTINCT isn't what you want: you need a GROUP BY[^] clause.
If you GROUP BY id1 with a WHERE selecting for true entries only, the COUNT method will return 1 for each id value - which means you aren't interested in it.

So try this:

SQL

SELECT id1 FROM MyTable GROUP BY id1 WHERE status = 1 HAVING COUNT(id1) = 2

Posted 30-Aug-23 20:39pm

OriginalGriff

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Richard Deeming · Accepted Answer · 2023-08-30T21:07:00

Solution 2

Griff's answer works if you only have two entries for each id1. But there's nothing in your question to suggest such a limitation. :)

A correlated sub-query with a Not Exists is probably the clearest solution:

SQL

SELECT DISTINCT id1
FROM A As A1
WHERE Not Exists
(
    SELECT 1
    FROM A As A2
    WHERE A2.id1 = A1.id1
    And A2.status = 0
)

Alternatively, you could use EXCEPT:

SQL

SELECT id1 FROM A WHERE status = 1
EXCEPT
SELECT id1 FROM A WHERE status = 0

EXCEPT and INTERSECT (Transact-SQL) - SQL Server | Microsoft Learn[^]

Posted 30-Aug-23 21:07pm

Richard Deeming

Comments

OriginalGriff 31-Aug-23 4:56am

"I want to make sure the status is true in both the rows."
Hence a "two row per ID" solution :D

Richard Deeming 31-Aug-23 4:58am

Agreed, the question isn't entirely clear. The sample data only shows two rows for each id1 value, but there's no indication that there couldn't be more (or less) than two. :)

Member 11314626 31-Aug-23 6:20am

Yes, I realised after seeing answer from OriginalGriff. Thank you both :)! Played with Not Exists and Except, both worked.