If classes ‘Math’ or ‘Biology’ have flag is NULL or = 0, we need to left join with the first appeared (according to the date) classes ‘Literature’ or ‘English Literature’ from the below. If classes ‘Math’ or ‘Biology’ have flag = 1 then we need to left join with the most recent (according to the date) classes ‘Literature’ or ‘English
Tag: left-join
How to differentiate between no rows and foreign key reference not existing?
My users table contains Alice, Bob and Charles. Alice and Bob have a 3 and 2 fruits respectively. Charles has none. A relationship is established using a foreign key constraint foreign key (user_id) references users (id) and a unique (user_id, name) constraint, allowing zero or one fruit per user. Charles does not have an orange, so there is no resulting
expected that this query will not output 0 values, but it does [closed]
Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed last month. Improve this question I expected that this query will not output 0 values, but it does. I thought that and (…) > 0 will not output 0 values. So
Join count query into one
I have two very simple count queries that I would like to join into one. To clarify the situation I will add the tables I got: Book isbn author 1111 GB 2222 DC 3333 RL Author code Name GB George B. KL Kyle L. DC Donald C. RL Roland L. Coauthor name isbn KL 1111 GB 2222 GB 3333 And
What will be the output of the left join? [closed]
Closed. This question needs debugging details. It is not currently accepting answers. Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question. Closed 8 months ago. Improve this question I have 2 tables A and B. Table A has 3 rows and
In Postgresql, how do I use joins with multiple conditions including >= and <=
I have table A and table B. Each row in table A represents every time a user sends a message. Each row in table B represents every time a user buys a gift. Goal: for each time a user sends a message, calculate how many gifts they’ve purchased within 7 days before the timestamp they sent the message. Some users
COUNT to return NULL as 0 in same table in SAS PROC SQL with GROUP BY
I am having a task where I have 1 table. There is a unique ID for transactions, transaction dates, and store names. My task would be to count the number of transactions every store made during March. This, in itself, is simple: This would lead to a table where a store is present only if it had a transaction in
Getting null data for left join on same table twice
I have some tables like this: Employee: Teams: TeamMember: I am trying to get list of employees with info regarding who they are : Team Member or Team Leader or Individual. Current output: Expected output: Query: Only issue here is that I am getting TeamId and TeamName as blank for “Team Leader” data as shown below: Current output: Can anyone
MySQL – category with product count not showing all results
I am trying to display the count of products along with the category name in the category list. I was able to achieve this with JOIN, but not all categories are displayed. I mean the categories with 0 products were not displayed, but I changed the JOIN to LEFT JOIN which displayed only one category with 0 products. There are
SQL: JOIN vs LEFT OUTER JOIN?
I have multiple SQL queries that look similar where one uses JOIN and another LEFT OUTER JOIN. I played around with SQL and found that it the same results are returned. The codebase uses JOIN and LEFT OUTER JOIN interchangeably. While LEFT JOIN seems to be interchangeable with LEFT OUTER JOIN, I cannot I cannot seem to find any information