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I am just starting to learn SQL. Can someone explain what ON means in the example?
SELECT title, imdb_score
FROM films
JOIN reviews
ON films.id = reviews.film_id
WHERE title = 'To Kill a Mockingbird';
ON films.id = reviews.film_id
To specify JOIN condition. With ON clause you specify exactly on which column you want to match both table records. You can as well specify extra conditions like
ON films.id = reviews.film_id
AND <more condition>
'ON' shows the connection between tables. For your example, the main table is 'films' and you want to bring data from table 'reviews'. If you dont tell computer how to connect data it cant know which movie has which reviews. You are saying that id's are the same for both of this table when you use 'ON'
It's a join condition.
In your example you will get title and imdb_score from those rows from films and reviews, which have the same id and film_id.
https://www.geeksforgeeks.org/sql-on-clause/
I would add for better readability, the ON right next to the table name you want to join
SELECT title, imdb_score
FROM films
JOIN reviews ON films.id = reviews.film_id
WHERE title = 'To Kill a Mockingbird';
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I have this SQL statement:
select
v.venue_id, v.name
from
venues v
where
not exists (select e.vid
from events e
where e.vid = v.venue_id);
Here is the result of the query:
It works fine but the last row in the result is null, how do I remove that? Been trying for a bit now with no luck
I think this might be what you're experiencing
Why does SQL workbench always return a row full of null values in every query?
Looks like that's normal behavior
The null row is per design, disregard it. i thought you were firstly referring to a column.
on your where statement <field> is not null
So:
select v.venue_id, v.name
from venues v
where not exists (
select e.vid
from events e
where e.vid = v.venue_id
and name is not null
);
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I have a table SQL server with two joining or bridging tables because of the many-to-many relationship.
I wonder if anyone can write the query to retrieve data or perform CRUD operations for this table that updates all these three tables.
Please check the attached Diagram particularly the table (Case, Violence_type, and Referral table in the middle where it has a bridging table).
Click to see DB diagram
Yours, omer
So you're trying to link e.g. Case to Referral via the association table Case_Referral? So what's the issue you're facing?
This is a pretty simple, straightforward SQL statement - SELECT from Case, join on Case_Referral via the case_id key, then join to Referral using the referral_id, and specify which columns from each table you need:
SELECT
c.user_name, c.date as CaseDate, c.priority, c.case_status,
r.date AS ReferralDate, r.referral_name
FROM
dbo.Case c
INNER JOIN
dbo.Case_Referral cr ON c.case_ID = cr.case_ID
INNER JOIN
dbo.Referral r ON cr.referral_ID = r.referral_ID
So what is the issue / problem you're not understanding?
You can use the same "technique" to join the other m:n relationships.
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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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Ok, basically I've got a lot of temp tables I've created and I'm trying to create Validation for the ProvDiff table.
DROP TABLE #ProvDiff;
IF OBJECT_ID ('temp.dbo.#ProvDiff') IS NOT NULL
DROP TABLE #ProvDiff;
SELECT *
INTO #ProvDiff
FROM
(SELECT DISTINCT *
FROM #finalclaimswithflags f
WHERE f.[Pay-To Prov NPI] <> f.[Rendering Prov NPI]) ProvDiff;
SELECT DISTINCT COUNT(DISTINCT ???) AS 'Unique EI NPIS'
FROM #ProvDiff
In my head it seems like the differences should be able to produce a result and I should be able to do a count on that. But for the life of me I can't figure out how to do that. If I do a count on rendering or pay to then those numbers wouldn't necessarily reflect the value for what are above. I know how many of each are produced for above validation.
Any help would be greatly appreciated
Is this what you want?
SELECT COUNT(*)
FROM (SELECT DISTINCT *
FROM #finalclaimswithflags f
WHERE f.[Pay-To Prov NPI] <> f.[Rendering Prov NPI]
) ProvDiff;
I don't see why a temporary table would be used for this.
For better or worse, SQL Server does not support select count(distinct *), so you pretty much need a subquery.
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Let me make it clear -
I have a table with information such as CourseID, Semester, GPA
I need to find all the CourseID's that have the same GPA(and some more fields) as CourseID='999'
I would also like a solution with AND without nested SELECT
Thanks!
So I have to find all the courseCode that has the same GPA and FailPerc as (Code 999, Year 2011, Sem B, Date 2)
Hope it's more clean now
this might work...
select c1.*
from course c1
inner join course c2 on c1.pga= c2.pga
where c2.courseid = 999
and c1.courseid <> c2.courseid
with subselects
select c1.*
from couser c1
where pga = (select pga
from course c2
where c2.courseid=999)
and c1.courseid <> 999
Before you run any query you need to somehow retrieve the data for the original data row. Unless you're writing your SQL for something like MS Access and can use domain functions like DLOOKUP(), I don't see any other way how you can get this information. This means, you need at least 2 SELECT queries and they must be nested.