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database week1 #21

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database week1 #21

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56 changes: 56 additions & 0 deletions databases/week1/database1-week1.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
SELECT COUNT(*)
FROM task;

SELECT COUNT(*)
FROM task
WHERE due_date IS NULL;

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'
);
Comment on lines +8 to +22
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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 *
FROM task
ORDER BY created DESC;

SELECT *
FROM task
ORDER BY created DESC LIMIT 1;

SELECT title
,due_date
FROM task
WHERE title LIKE '%database%'
OR description LIKE '%database%';

SELECT title
,(
SELECT NAME
FROM STATUS
WHERE id = task.status_id
) AS status_text
FROM task;
Comment on lines +38 to +44
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Very good here,thx.


SELECT STATUS.NAME
,COUNT(*) AS count
FROM task
INNER JOIN STATUS ON task.status_id = STATUS.id
GROUP BY STATUS.id;

SELECT STATUS.NAME
FROM task
INNER JOIN STATUS ON task.status_id = STATUS.id
GROUP BY STATUS.id
ORDER BY COUNT(*) DESC;