database week1 #21
database week1 #21
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Good job in general and would just want you to remember always use the same format. A table or column naming should always be in the same format(where you use lower case, & upper case like task, and STATUS but will expect the table names to be made as task, status, etc) for good practice & minimize errors.
This might only not be a doubt when it comes to OS.
In MySQL, the default behavior regarding case-sensitivity depends on the underlying operating system. On Windows, table and column names are not case-sensitive by default, while on Unix/Linux platforms, they are case-sensitive.
You can merge it & pay extra attention in the issues mentioned above.
| SELECT * | ||
| FROM task | ||
| WHERE status_id = ( | ||
| SELECT id | ||
| FROM STATUS | ||
| WHERE NAME = 'done' | ||
| ); | ||
|
|
||
| SELECT * | ||
| FROM task | ||
| WHERE status_id != ( | ||
| SELECT id | ||
| FROM STATUS | ||
| WHERE NAME = 'done' | ||
| ); |
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Here I can't see in which status a task is as I (any external viewer) will not understand (not easily if at least) what status_id=3 meant. We don't even have a status name in the table task. So we need to get some information from other related tables (by joining).
Check this if it can help---
SELECT task.id,title,due_date, status.name
FROM task
JOIN status ON task.status_id=status.id
WHERE status.name="Done";
-- Find all the tasks that are not marked as not done
SELECT task.id,title,due_date, status.name
FROM task
JOIN status ON task.status_id=status.id
WHERE status.name!="Done";
| SELECT title | ||
| ,( | ||
| SELECT NAME | ||
| FROM STATUS | ||
| WHERE id = task.status_id | ||
| ) AS status_text | ||
| FROM task; |
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