I have two tables 'property' and 'bookings'. I want to find out property for city, checkin and checkout when bookings table is empty.
when bookings table empty, for city = 'bali' and checkin = '2020-07-20' and checkout = '2020-07-30', expected output is property id 1 and 2.
when bookings table not empty, for city = 'bali' and checkin = '2020-07-20' and checkout = '2020-07-30', expected output is property id 1.
Query should work both when bookings table is empty / not empty.
property:
+----+---------+------+
| id | city | type |
+----+---------+------+
| 1 | bali | 1 |
| 2 | bali | 1 |
| 3 | bangkok | 1 |
+----+---------+------+
bookings:
+----+-------------+------------+------------+
| id | property_id | checkin | checkout |
+----+-------------+------------+------------+
| 1 | 1 | 2020-07-18 | 2020-07-19 |
| 2 | 2 | 2020-07-20 | 2020-07-25 |
| 3 | 3 | 2020-07-20 | 2020-07-30 |
+----+-------------+------------+------------+
What will be best approach subquery or left join? I tried both approach but unable to get the expected result.
As #Strawberry suggested, I am able to make it work:
SELECT property.id FROM property
LEFT JOIN bookings
ON bookings.checkin < '2020-08-30'
AND bookings.checkout > '2020-08-20'
AND bookings.property_id = property.id
WHERE city = 'bali'
AND bookings.id IS NULL
Try this:
SELECT *
FROM property
LEFT JOIN bookings ON bookings.property_id = property.id
WHERE city='bali'
AND IF(bookings.id IS NULL, 1, bookings.checkin = '2020-07-18')
AND IF(bookings.id IS NULL, 1, bookings.checkout = '2020-07-19')
If there doesn't exists any record in the bookings table then simply apply the filter on the city only otherwise filter will be applied ont eh checkin and checkout as well.
Related
I have two tables and need to get all rows from the first one and then check which values from the second table match the first table.
My goal is to get all so called 'achievements' and then check which one the user has reached.
achievements
+---------------+-------------+
| achievementID | description |
+---------------+-------------+
| 1 | goal1 |
| 2 | goal2 |
| 3 | goal3 |
+---------------+-------------+
achievement_user
+---------------------+---------------+--------+
| achievementRecordID | achievementID | userID |
+---------------------+---------------+--------+
| 1 | 1 | 1 |
| 2 | 1 | 3 |
| 3 | 4 | 2 |
| 4 | 3 | 1 |
+---------------------+---------------+--------+
My desired result for a query where I check the results for userID = 1 would be something like
+---------------+---------------+--------------+
| achievementID | description | solvedByUser |
+---------------+---------------+--------------+
| 1 | goal1 | true |
| 2 | goal2 | false |
| 3 | goal3 | true |
+---------------+---------------+--------------+
The new column solvedByUser could be basically any datatype (boolean, int, ...).
I just need a list of all available achievements and then see which one the user has reached.
You can left join the achievments table with achievement_user:
select a.*, (au.userID is not null) solvedByUser
from achievements a
left join achievement_user au
on au.achievementID = a.achievementID
and au.userID = 1
solvedByUser is a 0/1 flag that indicates whether the given achievement was reached by the given user.
I think you need a left join -
SELECT A.achievementID, A.description, CASE WHEN AU.userID IS NOT NULL THEN 'true' ELSE 'false' solvedByUser
FROM achievements A
LEFT JOIN achievement_user AU ON A.achievementID = AU.achievementID
AND userID = 1; -- YOUR INPUT ID
You need a left join:
select a.*,
case when u.achievementID is null then 'false' else 'true' end solvedByUser
from achievements a left join achievement_user u
on u.achievementID = a.achievementID and u.userid = 1
I need to retrieve rows from a mysql database as follows: I have a contract table, a contract line item table, and another table called udac. I need all contracts which DO NOT have a line item record with criteria based on a relationship between contract line item and udac. If there is a better way to state this question, let me know.
Table Structures
----contract--------------------- ---contractlineitem-----------
| id | customer_id | entry_date | | id | contract_id | udac_id |
--------------------------------- ------------------------------
| 1 | 1234 | 2010-01-01 | | 1 | 1 | 5 |
| 2 | 2345 | 2016-01-31 | | 2 | 1 | 2 |
--------------------------------- | 3 | 1 | 1 |
| 4 | 2 | 4 |
| 5 | 2 | 2 |
------------------------------
---udac----------
| id | udaccode |
-----------------
| 1 | SWBL/R |
| 2 | SWBL |
| 3 | ABL/R |
| 4 | ABL |
| 5 | XRS/F |
-----------------
Given the above data, contract 2 would show up but contract 1 would not, because it has contractlineitems that point to udacs that end in /F or /R.
Here's what i have so far, but it's not correct.
SELECT c.*
FROM contract c
JOIN contractlineitem cli
ON c.id = cli.contract_id
WHERE c.entry_timestamp > '2016-01-01 00:00:00'
AND NOT EXISTS (
SELECT cli.id
FROM contractlineitem cli_i
JOIN udac u
ON cli_i.udac_id = u.id
WHERE u.udaccode LIKE '%/F' OR u.udaccode LIKE '%/R'
AND cli_i.contract_id = cli.contract_id);
Tom's comment that your WHERE clause is wrong may be the problem you are chasing. Plus, using a correlated subquery may be problematic for performance if the optimizer can't figure out a better way to do it.
Here is the better way to do it using an OUTER JOIN:
SELECT c.*
FROM contract c
JOIN contractlineitem cli
ON c.id = cli.contract_id
LEFT OUTER JOIN udac u
ON ( u.id = cli.udac_id
AND ( u.udaccode LIKE '%/F' OR u.udaccode LIKE '%/R' ) )
WHERE c.entry_timestamp > '2016-01-01 00:00:00'
AND u.id IS NULL
Try that out and see if it does what you want. The query essentially does what you stated: It tries to join to udac where the code ends in '/F' or '/R', but then it only accepts the ones where it can't find a match (u.id IS NULL).
If the same row is returned multiple times incorrectly, throw a distinct on the front.
I have a basic table:
+-----+--------+------+------+
| id, | name, | cat, | time |
+-----+--------+------+------+
| 1 | jamie | 1 | 100 |
| 2 | jamie | 2 | 100 |
| 3 | jamie | 1 | 50 |
| 4 | jamie | 2 | 150 |
| 5 | bob | 1 | 100 |
| 6 | tim | 1 | 300 |
| 7 | alice | 4 | 100 |
+-----+--------+------+------+
I tried using the "Left Joining with self, tweaking join conditions and filters" part of this answer: SQL Select only rows with Max Value on a Column but some reason when there are records with a value of 0 it breaks, and it also doesn't return every unique answer for some reason.
When doing the query on this table I'd like to receive the following values:
+-----+--------+------+------+
| id, | name, | cat, | time |
+-----+--------+------+------+
| 1 | jamie | 1 | 100 |
| 4 | jamie | 2 | 150 |
| 5 | bob | 1 | 100 |
| 6 | tim | 1 | 300 |
| 7 | alice | 4 | 100 |
+-----+--------+------+------+
Because they are unique on name and cat and have the highest time value.
The query I adapted from the answer above is:
SELECT a.name, a.cat, a.id, a.time
FROM data A
INNER JOIN (
SELECT name, cat, id, MAX(time) as time
FROM data
WHERE extra_column = 1
GROUP BY name, cat
) b ON a.id = b.id AND a.time = b.time
The issue here is that ID is unique per row you can't get the unique value when getting the max; you have to join on the grouped values instead.
SELECT a.name, a.cat, a.id, a.time
FROM data A
INNER JOIN (
SELECT name, cat, MAX(time) as time
FROM data
WHERE extra_column = 1
GROUP BY name, cat
) b ON A.Cat = B.cat and A.Name = B.Name AND a.time = b.time
Think about it... So what ID is mySQL returning form the Inline view? It could be 1 or 3 and 2 or 4 for jamie. Hows does the engine know to pick the one with the max ID? it is "free to choose any value from each group, so unless they are the same, the values chosen are indeterminate. " it could pick the wrong one resulting in incorrect results. So you can't use it to join on.
https://dev.mysql.com/doc/refman/5.0/en/group-by-handling.html
If you want to use a self join, you could use this query:
SELECT
d1.*
FROM
date d1 LEFT JOIN date d2
ON d1.name=d2.name
AND d1.cat=d2.cat
AND d1.time<d2.time
WHERE
d2.time IS NULL
It is very simple
SELECT MAX(TIME),name,cat FROM table name group by cat
I don't know if a similar question have been asked, but I looked fow more than hour on mysql in stackoverflow
My problem is, i have multiple tables and I need to join them with both left join and inner join in mysql
Entity table :
id (key) | entityName
1 | john
2 | harris
3 | henry
4 | mark
5 | dom
Activity table
id (key) | entityID | status
1 | 1 | 1
2 | 2 | 0
3 | 4 | 1
Geodata table
id (key) | entityID | moment (timestamps when the entry was done)
1 | 1 | 1429542320 (smaller)
2 | 1 | 1429542331 (bigger)
3 | 2 | 1429542320 (smaller)
4 | 2 | 1429542331 (biger)
5 | 4 | 1429542331 (bigger)
Info table
id (key) | entityID | infos | date
1 | 1 | xxx | today
2 | 1 | xxx | yesterday
3 | 2 | xxx | today
4 | 2 | xxx | yesterday
5 | 3 | xxx | yesterday
6 | 5 | xxx | today
7 | 5 | xxx | yesterday
8 | 5 | xxx | tomorrow
So basically, I need every Entities that has an info for today
Moreover, if their status is true (or 1) (from activity table), show me their date in geodata table.
So this is what i've got :
SELECT e.id,
e.entityName,
i.infos,
a.status,
MAX(g.moment) -- but the max only if status =1
FROM entities AS e
LEFT JOIN activity AS a ON a.entityID = e.id
LEFT JOIN geodata AS g ON g.entityID = e.id
INNER JOIN infos AS i ON e.id = i.entityID
WHERE i.date = 'today'
GROUP BY e.id
I want every entities that has an info about today, but some of them have activity too, so i want to show it (if it doesn't just let the left join put NULL) If the status is 0, I don't need the moment, but if its true, I only need the bigger one (its numbers, so Max() should do it but it breaks)
The expected results is :
id (key) | entityName | infos | status | MAX(moment) | ..other columns
1 | john | xxx | 1 | 1429542331 (the bigger one)
2 | harris | xxx | 0 | NULL
5 | dom | xxx | NULL | NULL
If someone can help me, I'll be very thankful :)
PS.: Sorry for my english, it isn't my first language
You could change the
MAX(g.moment)
to
IF(a.status<>1, NULL, MAX(g.moment))
or alternately change LEFT JOIN geodata AS g ON g.entityID = e.id to LEFT JOIN geodata AS g ON a.entityID = e.id AND a.status = 1
Which one is faster will probably depend on your actual data; the second may be faster as less records are joined, but the more complicated join condition it uses might slow down the joining.
I have table A
| id | Name |
_________________________
| 1 | ABC |
_________________________
| 2 | BCD |
_________________________
Table B
| id | a_id | Status | timestamp |
__________________________________________________________
| 1 | 1 | 1 | timestamp |
__________________________________________________________
| 2 | 1 | 2 | timestamp |
__________________________________________________________
| 3 | 1 | 3 | timestamp |
__________________________________________________________
| 4 | 2 | 1 | timestamp |
__________________________________________________________
In above example I only want to pick
| name | a_id | Status | timestamp |
__________________________________________________________
| BCD | 2 | 1 | timestamp |
So with any record that has ONLY and ONLY latest STATUS as 1, I want to pick that record.. If the LATEST STATUS is 2 or 3, I don't want ot pick them...
If possible I don't want to use sub-query because I am using Codeigniter which doesn't really like subqueries.
Please help
So that will be:
SELECT
A.name,
B.*
FROM
(SELECT
a_id,
MAX(`timestamp`) AS max_timestamp
FROM B
GROUP BY a_id) AS latest
LEFT JOIN B
ON
B.a_id=latest.a_id
AND
B.`timestamp`=latest.max_timestamp
LEFT JOIN A
ON B.a_id=A.id
WHERE
B.status=1
As for subquery - I doubt you can retrieve desired information without that in single query. That is because you need to use row set, which is a result of grouping by one column, in reference to another column. And so you need to group that first, and then apply JOIN to result row set.
Thanks to #Strawberry for pointing to this article, I figured a way to do it for this example.
select a.name
,b1.a_id
,b1.status
,b1.`timestamp` AS b1Time
FROM TableA a
JOIN TableB b1 ON b1.a_id = a.id
LEFT JOIN TableB b2 ON b2.a_id = b1.a_id AND b1.`timestamp` < b2.`timestamp`
WHERE b2.`timestamp` IS NULL
AND b1.status = 1
See this Fiddle.