Linked Questions

Question 1

I was just writing a query when I thought of this. My query will yield exactly the same result using either inner join or left join, since I'm joining tables on a foreign key relationship, selecting ...

Question 2

Suppose I have 2 tables, Products and ProductCategories. Both tables have relationship on CategoryId. And this is the query. SELECT p.ProductId, p.Name, c.CategoryId, c.Name AS Category FROM Products ...

Question 3

Many experienced developers recommend against using Django multi-table inheritance because of its poor performance: Django gotcha: concrete inheritance by Jacob Kaplan-Moss, a core contributor of ...

Question 4

I would like to know which one is best regarding performance between the 2 queries stated below or do they perform identically? First one: [without WHERE clause, just AND with ON] SELECT ...

Question 5

I have a table (MainTable) with a bit over 600,000 records. It joins onto itself via a 2nd table (JoinTable) in a parent/child type relationship: SELECT Child.ID, Parent.ID FROM MainTable AS ...

Question 6

If both inner join and left join can achieve the same result, which one is faster and has better performance (especially on large data)? inner join: SELECT * FROM Table_A A INNER JOIN Table_B B ON A....

Question 7

I have two postgres tables: worker_details_verification (verification_id BIGSERIAL, worker_id BIGINT, state TEXT, proofs TEXT[]) worker_details(worker_id BIGINT, name TEXT) Now I want to get `...

Question 8

Is there any difference between left join and inner join regarding performance? I use SQL Server 2012.

Question 9

Is there a performance difference in the following? SELECT person.id FROM person LEFT JOIN address ON person.id = address.personID WHERE address.personID IS NOT NULL vs SELECT person.id FROM person ...

Question 10

I have two tables Table X: millions or records |-----|-----|-----|-----| | a | b | c | d | |-----|-----|-----|-----| Table Y: only a few records |-----|-----| | e | f | |-----|-----| X....

Question 11

I have always thought that Inner Join performs better than Outer JOIN, but I've experienced several cases now where this simply isn't true... The other day I was creating a query with a series of ...

Question 12

Do the queries do the same? What is the standard? Will I lose performance if I change one of these ways of write the query? Query 1 SELECT a.*, b.id AS b_id FROM table_a AS a LEFT JOIN ...

Question 13

By experimentation and surprisingly, I have found out that LEFT JOINING a point-table is much faster on large tables then a simple assigning of a single value to a column. By a point-table I mean a ...

Question 14

I have two tables: sk_accounts //details of user acnt_user_id acnt_fname //first name acnt_lname acnt_profile_picture acnt_member_class so on........ sk_following //table containing ...

Question 15

I have a database with 20 tables inside it. I want to fetch records from 10 related tables at a time, and I am using Hibernate. What is the best solution: to write a single query using join with ...

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