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I need to remove values that has null result (second row)
Your query that you posted uses correlated sub queries to get the results that could easily achieved with a left join. Changing that left join into an inner join will get rid of the nulls as long as you do not have nulls in the name column of the emp table.
select e.empno,e.ename,mngr.name
from emp e
inner join emp mngr on e.mgr=mngr.empno
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I need help regarding SQL joins, i am trying join two tables as shown in below images
I guess you can try the below query to get the desired result -
SELECT CASE WHEN CT.partner2 IS NULL
THEN C.partner_id
ELSE CT.partner1
END Partner1,
CT.partner2,
C.Type,
C.Company_name,
C.First_name,
CT.city,
CT.Phone,
CT.Email
FROM CUSTOMER C
LEFT JOIN CONTACTS CT ON C.partner_id = CT.partner2
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Inner joining tables A and B returns 50 rows. Left join B to A returns 125 rows. What's going on here?
Left join can be bigger than inner join, and contain the same data + more data from table A.
Look at the following chart for reference:
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Permission to ask, why is this the error? I try
select user_idea.idea_id,user_idea.title, idea_events.events, idea_categories.category_name AS category
from user_idea
LEFT join idea_events
on user_idea.idea_id=idea_events.idea_id
LEFT JOIN idea_categories
ON user_idea.idea_categories=idea_categories.category_id;
The result is sqliteonline like this:
I want to combine Dewasa and Anak events because of the same idea. For category why is the result NULL for values 1;2 not read in the idea_category table which should be Mudah; Sedang.
For table:
Output expected:
select user_idea.idea_id,user_idea.title,
(SELECT GROUP_CONCAT(events,';') FROM idea_events Where user_idea.idea_id=idea_events.idea_id) as events,
(SELECT GROUP_CONCAT(category_name ,';') FROM idea_categories Where user_idea.idea_categories=idea_categories.category_id) AS category
from user_idea;
1:2 idea_categories in user_idea is not considered as relevant to join so when joined it cannot find the data in other table here so data is null
reminder
before doing join just analyse the data anomalies like not having common data and properly formatted
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How do I write a query in sql to update the salary of each instructor to 10,000 times the number of course sections they have taught given the schema below?
Here is the schema of the database:
Query:
UPDATE instructor
SET salary = 10000 *
(SELECT COUNT(*) FROM section s
JOIN teaches t ON s.sec_id = t.sec_id
JOIN instructor i ON t.id = i.id
WHERE i.id = instructor.id);
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How can I write a SQL query that will replace the "ComputerID" and "PartID" with the "UnitNumber". The ComputerID's and PartID's are in the same column under InventoryID. The InventoryID's are unique but the UnitNumber (sticker label/name) doesn't have this requirement.
Here are the tables and how they relate.
Let's call your tables Object and Inventory
If you use a couple of joins then this should work:
select o.ObjectID as ObjectID, a.UnitNumber as Computer, b.UnitNumber as Part,
o.InputID from Object o
join Inventory a on a.InventoryID=o.CombputerID
join Inventory b on b.InventoryID=o.PartID