I have a table like
ID | ParentID |Children| Name | Address
----------------------------------------
1 | Null | | Xyz | Home
2 | 1 | | ABC | Home
3 | 2 | | DEF | Home
4 | 3 | | GHI | Home
5 | 3 | | GHI | Home
6 | 1 | | GHI | Home
I need to fill the Children with a query, these are immediate children. For example children for 1 will be 2 and children for 3 will be 4,5
So the table after query should look like
ID | ParentID |Children| Name | Address
----------------------------------------
1 | Null | 2,6 | Xyz | Home
2 | 1 | 3 | ABC | Home
3 | 2 | 4,5 | DEF | Home
4 | 3 | Null | GHI | Home
5 | 3 | Null | GHI | Home
6 | 1 | Null | GHI | Home
I know I can use group_concat function with update query but not getting the exact query. How can I do this with a MySQL query?
You can create a subquery which concatenate the ID for its children and join it with the table itself.
UPDATE tableName a
INNER JOIN
(
SELECT a.ID, GROUP_CONCAT(b.ID) Children
FROM tableName a
INNER JOIN tableName b
ON a.ID = b.ParentID
GROUP BY a.ID
) b ON a.ID = b.ID
SET a.Children = b.Children
Related
so what I am trying to do is having 3 tables (pictures, collections, and bridge) with the following columns:
Collections Table:
| id | name |
------------------
| 1 | coll1 |
| 2 | coll2 |
------------------
Pictures Table: (timestamps are unix timestamps)
| id | name | timestamp |
-------------------------
| 5 | Pic5 | 1 |
| 6 | Pic6 | 19 |
| 7 | Pic7 | 3 |
| 8 | Pic8 | 892 |
| 9 | Pic9 | 4 |
-------------------------
Bridge Table:
| id | collection | picture |
-----------------------------
| 1 | 1 | 5 |
| 2 | 1 | 6 |
| 3 | 1 | 7 |
| 4 | 1 | 8 |
| 5 | 2 | 5 |
| 6 | 2 | 9 |
| 7 | 2 | 7 |
-----------------------------
And the result should look like this:
| collection_name | picture_count | newest_picture |
----------------------------------------------------
| coll1 | 4 | 8 |
| coll2 | 3 | 9 |
----------------------------------------------------
newest_picture should always be the picture with the heighest timestamp in that collection and I also want to sort the result by it. picture_count is obviously the count of picture in that collection.
Can this be done in a single statement with table joins and if yes:
how can I do this the best way?
A simple method uses correlated subqueries:
select c.*,
(select count(*)
from bridge b
where b.collection = c.id
) as pic_count,
(select p.id
from bridge b join
pictures p
on b.picture = b.id
where b.collection = c.id
order by p.timestamp desc
limit 1
) as most_recent_picture
from collections c;
A more common approach would use window functions:
select c.id, c.name, count(bp.collection), bp.most_recent_picture
from collections c left join
(select b.*,
first_value(p.id) over (partition by b.collection order by p.timestamp desc) as most_recent_picture
from bridge b join
pictures p
on b.picture = p.id
) bp
on bp.collection = c.id
group by c.id, c.name, bp.most_recent_picture;
I have the following table named Booking_tbl:
+-----------+---------+----------+
| BookingId | ClassId | UserName |
+-----------+---------+----------+
| 1 | 6 | Student1 |
| 2 | 6 | Student2 |
| 3 | 6 | Student3 |
| 4 | 6 | Student4 |
| 5 | 3 | Student5 |
| 6 | 4 | Student4 |
| 7 | 5 | Student3 |
| 8 | 6 | Student2 |
+-----------+---------+----------+
I also have this table named Class_tbl:
+---------+------------+
| ClassId | ClassLimit |
+---------+------------+
| 1 | 57 |
| 2 | 3 |
| 3 | 43 |
| 4 | 34 |
| 5 | 5 |
| 6 | 3 |
+---------+------------+
I want to be able to write an SQL statement that returns all the classId's in which the booking limit has not been met. Since the booking table does not contain the class limit, I am unsure on how I can make this work. I have heard about sub queries, but do not know how to use them. I have this so for.
SELECT ClassId,
IF((SELECT COUNT(*) FROM Booking_tbl WHERE ClassId = 3)<
(SELECT ClassLimit FROM Class_tbl WHERE ClassId = 3),
'true','false') AS "TRUE/FALSE"
FROM Class_tbl WHERE ClassId = 3;
I don't know how to make this into a query whose result will give me a list of all the classId's whose limit is not yet reached.
Try with sub query as:
SELECT c.ClassId
FROM class_tbl as c
LEFT JOIN(SELECT class_tb.ClassId, COUNT(Booking_tbl.ClassId) as total_booked
FROM class_tbl
LEFT JOIN Booking_tbl on class_tbl.ClassId=Booking_tbl.ClassId
GROUP BY class_tbl.ClassId) as b ON b.ClassId = c.ClassId
WHERE c.ClassLimit > total_booked
My database looks like this, I have client accounts which are assigned to specific profiles, and I have profiles which are assigned to specific categories, like in this schema:
| categories | | profiles | | categories_map |
--------------- ------------- ----------------------------
| ID | name | | ID | name | | ID | profile_id | cat_id |
--------------- ------------- ----------------------------
| 1 | cat1 | | 1 | p1 | | 1 | 1 | 1 |
| 2 | cat2 | | 2 | p2 | | 2 | 2 | 1 |
| 3 | cat3 | | 3 | p3 | | 3 | 3 | 1 |
| 4 | p4 | | 4 | 1 | 2 |
| 5 | 3 | 2 |
| 6 | 4 | 3 |
| profiles_map |
-----------------------------
| ID | profile_id | acc_id |
-----------------------------
| 1 | 1 | 1 |
| 2 | 3 | 1 |
| 3 | 4 | 1 |
I need to get categories assigned to accounts - which means when I want to get categories for acc_id = 1, I should get categories with ID 2 and 3 ( category with ID 2 doesn't fit because it contains profile with ID 2 which isn't assigned to this account). I tried this query but it doesn't work
select cats.id from profiles_map map
right join categories_map catm on catm.profile_id = map.profile_id
right join categories cats on cats.id = catm.cat_id
where catm.profile_id in (select profile_id from profiles_map where acc_id = 1)
and map.acc_id = 1 group by cats.id;
Could anybody help me with this question?
Can you try this one?
SELECT DISTINCT C.ID
FROM profiles_map PM
INNER JOIN categories_map CM ON CM.profile_id = PM.profile_id
INNER JOIN categories C ON C.ID = CM.cat_id
WHERE PM.acc_id= 1
If you want to get only category id, Please try following query:
SELECT DISTINCT cm.cat_id FROM categories_map cm
WHERE cm.profile_id in
(SELECT profile_id FROM profiles_map WHERE acc_id = 1)
Or if want to get category name and id then , use following query:
SELECT cat.id,cat.name FROM categories cm
WHERE cat.id in (SELECT DISTINCT cm.cat_id FROM categories_map cm
WHERE cm.profile_id in
(SELECT pm.profile_id FROM profiles_map pm WHERE pm.acc_id = 1))
I would like to join two tables and select from two columns the first one if it is not null, of the other if the first is null. As an example imagine that we have the following tables:
names companies_to_names
-------------------------------- -----------------------------
|id_name | name | nickname | | id | id_name | id_company |
-------------------------------- -----------------------------
| 1 | NULL | manu | | 1 | 1 | 1 |
| 2 | Joe A. | NULL | | 2 | 2 | 1 |
| 3 | Bob B. | NULL | | 3 | 3 | 1 |
| 4 | NULL | alice | | 4 | 4 | 1 |
| 5 | NULL | other | | 5 | 5 | 2 |
-------------------------------- -----------------------------
And we want to show either the name, or the nickname of the guys who work for the company with id=1. Then, I want the following result:
--------------------
|id_name | username|
--------------------
| 1 | manu |
| 2 | Joe A. |
| 3 | Bob B. |
| 4 | alice |
--------------------
I was thinking in SELECT CASE WHEN, but I don't know how to do it. Something like:
SELECT NAMES.id_name CASE username
WHEN NAMES.name IS NULL THEN NAMES.nickname
WHEN NAMES.name IS NOT NULL THEN NAMES.name
END
FROM NAMES INNER JOIN COMPANIES_TO_NAMES ON NAMES.id_name = COMPANIES_TO_NAMES.id_name;
Am I right?
Here is a query that shows you how to solve your problem:
SELECT N.id_name
,IFNULL(N.name, N.nickname) AS [username]
,CASE
WHEN N.name IS NOT NULL THEN 'name'
ELSE 'nickname'
END AS [username_source]
FROM NAMES N
INNER JOIN companies_to_names C ON C.id_name = N.id_name
AND C.id = 1
Hope this will help you.
I have five mysql tables. shops
+----+--------------+--------------+
| id | name | address |
+----+--------------+--------------+
| 1 | Shop1 | Street1 |
| 2 | Shop2 | Street2 |
| 3 | Shop3 | Street3 |
| 4 | Shop4 | Street4 |
+----+--------------+--------------+
fruits
+----+--------------+--------------+
| id | fruit | price |
+----+--------------+--------------+
| 1 | Bannana | 2.5 |
| 2 | Apple | 2.1 |
| 3 | Orange | 1.8 |
| 4 | Plum | 2.2 |
+----+--------------+--------------+
availability
+----+--------------+--------------+
| id | shop_id | fruit_id |
+----+--------------+--------------+
| 1 | 1 | 2 |
| 2 | 2 | 2 |
| 3 | 1 | 3 |
| 4 | 2 | 1 |
+----+--------------+--------------+
shop_activity
+----+--------------+--------------+--------------+
| id | shop_id | user_id | status |
+----+--------------+--------------+--------------+
| 1 | 2 | 1 | 1 |
| 2 | 3 | 2 | 1 |
| 3 | 1 | 2 | 2 |
| 4 | 2 | 2 | 1 |
+----+--------------+--------------+--------------+
users
+----+--------------+
| id | name |
+----+--------------+
| 1 | Peter |
| 2 | John |
+----+--------------+
I have query
SELECT
availability.shop_id,
shops.name
FROM availability
LEFT JOIN shops
ON availability.shop_id=shops.id
WHERE
fruit_id = 2
As a result I get name list of shops where fruit with id 2 (apple) is available.
What should I do so that I can include shop_activity table in query to get user's status if users.id = 1 beside proper shop. Something like this...
Shop1, NULL
Shop2, status: 1
You could try something like this:
SELECT
availability.shop_id,
shops.name,
shop_activity.status
FROM availability
LEFT JOIN shops
ON availability.shop_id=shops.id
LEFT JOIN shop_activity
ON shop_activity.shop_id = availability.shop_id
and shop_activity.user_id = 1
WHERE
fruit_id = 2
SELECT
availability.shop_id,
shops.name
FROM shops
LEFT JOIN availability ON availability.shop_id=shops.id
LEFT JOIN shop_activity ON shop_activity .shop_id=shops.id
WHERE
fruit_id = 2
and users.id=1
try making shops as the first table in left join
Try the following:
SELECT shops.name, shop_activity.status
FROM shops
INNER JOIN availability ON availability.shop_id = shops.id
AND availability.fruit_id = 2
LEFT JOIN shop_activity ON shops.shop_id = shop_activity.shop_id
AND shop_activity.user_id = 1
This should give you a row for every shop with apples, but the status will show as null for shops where the user has no activity, otherwise shows the status of that user.