I have a table with data stored vertically, I have shown a simplified example below which has a record for each city a customer has lived in:
| CUSTOMER | CITY |
------------------------------
| John | London |
| John | Manchester |
| Sarah | Cardiff |
| Sarah | Edinburgh |
| Sarah | Liverpool |
| Craig | Manchester |
| Craig | London |
I am trying to come up with an SQL query that will return all unique combinations of cities so in the example above, John and Craig have both lived in London and Manchester but Sarah has lived in different cities (Cardiff, Edinburgh and Liverpool) so I would like an output as below (which can handle any amount of cities)
| CITY1 | CITY2 | CITY3 |
--------------------------------------------
| London | Manchester | |
| Cardiff | Edinburgh | Liverpool |
I have tried using a crosstab query to view the data horizontally like this:
TRANSFORM Max(City)
SELECT Customer
FROM tblCities
GROUP BY Customer
PIVOT City
but it is just returning a field for all cities for every customer. Does anyone know if this is possible using SQL?
p.s Ideally it will ignore the order of cities
This was a nice challenge! The query below gets the groupings per customer. It doesn't discard the duplicates where multiple customers have lived in the same combination of cities ... I'll let you or others find a way to handle that.
TRANSFORM Min(OrderedList.City) AS MinOfCity
SELECT OrderedList.Customer
FROM (SELECT CustomerCities.Customer, CustomerCities.City, Count(1) AS CityNo
FROM CustomerCities INNER JOIN CustomerCities AS CustomerCities_1 ON CustomerCities.Customer = CustomerCities_1.Customer
WHERE (((CustomerCities.City)>=[CustomerCities_1].[City]))
GROUP BY CustomerCities.Customer, CustomerCities.City) OrderedList
GROUP BY OrderedList.Customer
PIVOT "CITY" & [CityNo];
Is this what you want?
select distinct c1.city, c2.city
from tblCities as c1 inner join
tblCities as c2
on c1.customer = c2.customer and c1.city < c2.city;
This returns all pairs of cities that appear for any single customer.
Here is a query which might work assuming each customer is only associated with two cities:
SELECT DISTINCT t.city_1, t.city_2
FROM
(
SELECT MIN(CITY) AS city_1, MAX(CITY) AS city_2
FROM tblCities
GROUP BY CUSTOMER
) t
Related
I currently have a dataset that looks like this:
Personid | Question | Response
1 | Name | Daniel
1 | Gender | Male
1 | Address | New York, NY
2 | Name | Susan
2 | Gender | Female
2 | Address | Boston, MA
3 | Name | Leonard
3 | Gender | Male
3 | Address | New York, NY
I also have another table that looks like this (just the person id):
Personid
1
1
1
2
2
2
3
3
3
I want to write a query to return something like this:
Personid | Name | Gender | Address
1 |Daniel | Male | New York, NY
2 | Susan | Female | Boston, MA
3 |Leonard | Male | New York, NY
I think it's a mix of some sort of "transpose" (not sure if it's even available in SQL) and conditional statement on just the gender, but I'm having issues with getting the end result. Could anyone offer any advice?
Easiest way is just to link to the question table three times with different aliases.
select
p.person_id,
n.response as name,
g.response as gender,
a.response as address
from
person p
join question n
on n.personid = p.personid and n.question = 'Name'
join question g
on g.personid = p.personid and g.question = 'Gender'
join question a
on a.personid = p.personid and a.question = 'Address'
I'm assuming that your person table only has 3 rows not the 9 you've listed. if there are really 9, then just do a select distinct.
This is a textbook example of a pivot table. In postgresql it is implemented by the CROSSTAB function, which is available from the TABLEFUNC additional extension module.
If your need is really as simple as the provided MCVE, multiple JOIN’s might be enough, but in more complicated situations CROSSTAB is really the way to go, and worth the pain of installing an additional module, if it is not installed by default by your distro. In short, if your initial table is called dataset, and personid is an INT:
-- To execute as superuser. Be sure you have installed the extension
-- package. Execute once to install, it will stay in your database
-- ever since.
CREATE EXTENSION TABLEFUNC;
-- As normal user
SELECT * FROM CROSSTAB($$
SELECT personid, question, response FROM dataset
$$) AS ct(person INT, name TEXT, gender TEXT, address TEXT);
person | name | gender | address
--------+----------+---------+---------------
1 | Daniel | Male | New York, NY
2 | Susan | Female | Boston, MA
3 | Leonard | Male | New York, NY
(3 rows)
You can add WHERE clauses, JOIN with other tables, etc., according to your needs.
Here are the two tables i have: [all columns in both tables are of type "text"], Table name and the column names are in bold fonts.
Names
--------------------------------
Name | DoB | Team |
--------------------------------
Harry | 3/12/85 | England
Kevin | 8/07/86 | England
James | 5/05/89 | England
Scores
------------------------
ScoreName | Score
------------------------
James-1 | 120
Harry-1 | 30
Harry-2 | 40
James-2 | 56
End result i need is a table that has the following
NameScores
---------------------------------------------
Name | DoB | Team | ScoreData
---------------------------------------------
Harry | 3/12/85 | England | "{"ScoreName":"Harry-1", "Score":"30"}, {"ScoreName":"Harry-2", "Score":"40"}"
Kevin | 8/07/86 | England | null
James | 5/05/89 | England | "{"ScoreName":"James-1", "Score":"120"}, {"ScoreName":"James-2", "Score":"56"}"
I need to do this using a single SQL command which i will use to create a materialized view.
I have gotten as far as realising that it will involve a combination of string_agg, JOIN and JSON, but haven't been able to crack it fully. Please help :)
I don't think the join is tricky. The complication is building the JSON object:
select n.name, n.dob, n.team,
json_agg(json_build_object('ScoreName', s.name,
'Score', s.score)) as ScoreData
from names n left join
scores s
ons.name like concat(s.name, '-', '%')
group by n.name, n.dob, n.team;
Note: json_build_object() was introduced in Postgres 9.4.
EDIT:
I think you can add a case statement to get the simple NULL:
(case when s.name is null then NULL
else json_agg(json_build_object('ScoreName', s.name,
'Score', s.score))
end) as ScoreData
Use json_agg() with row_to_json() to aggregate scores data into a json value:
select n.*, json_agg(row_to_json(s)) "ScoreData"
from "Names" n
left join "Scores" s
on n."Name" = regexp_replace(s."ScoreName", '(.*)-.*', '\1')
group by 1, 2, 3;
Name | DoB | Team | ScoreData
-------+---------+---------+---------------------------------------------------------------------------
Harry | 3/12/85 | England | [{"ScoreName":"Harry-1","Score":30}, {"ScoreName":"Harry-2","Score":40}]
James | 5/05/89 | England | [{"ScoreName":"James-1","Score":120}, {"ScoreName":"James-2","Score":56}]
Kevin | 8/07/86 | England | [null]
(3 rows)
Apologies if a similar problem is posted earlier, I couldn't find the same.
Problem: I need to join two tables based a conditional look up in the second table.
Tables: Below are the two tables which have a subset of the total fields.
+-------------------------------------------------------+
| Persons |
+----------+------------+---------------+---------------+
| PersonID | PersonName | HomeAddressID | WorkAddressID |
+----------+------------+---------------+---------------+
| P1 | Doe, John | HA1 | WA1 |
+----------+------------+---------------+---------------+
| P2 | Doe, Jane | HA2 | WA2 |
+----------+------------+---------------+---------------+
| P3 | Doe, Jane | | WA3 |
+----------+------------+---------------+---------------+
+-----------------------------------+
| Addresses |
+-----------+--------+------+-------+
| AddressID | Street | City | State |
+-----------+--------+------+-------+
| HA1 | 123 | A | B |
+-----------+--------+------+-------+
| WA1 | 456 | C | D |
+-----------+--------+------+-------+
| HA2 | 111 | | |
+-----------+--------+------+-------+
| WA2 | 101 | G | H |
+-----------+--------+------+-------+
| WA3 | 333 | I | J |
+-----------+--------+------+-------+
Current Scenario: The SELECT query in a view fetches PersonName from first table and work address fields from second table. (Join is on WorkAddressID)
Expected Result: The SELECT query should fetch PersonName field from first table and address fields from second table conditions being:
If state for home address is available then display Street, City and State for home address.
If state for home address is NULL/blank then display Street, City and State for work address.
Notes:
Many rows in Persons table do not have HomeAddressID but all do have WorkAddressID.
Many rows in Addresses table do not have City and State information for Home addresses.
While this may look like a design flaw, I'm not in a position to re-engineer the database as there are hundreds of objects and sub-objects depending on the original view.
There are 3 million+ rows in the Persons table so performance needs to be acceptable.
The current query has joins to at least 5 other views.
Please advise as to how I can address this problem.
Many thanks,
-V
Here's a MySQL solution:
SELECT PersonName,
IF(h.State = '' OR h.State IS NULL, w.Street, h.Street) AS Street,
IF(h.State = '' OR h.State IS NULL, w.City, h.City) AS City,
IF(h.State = '' OR h.State IS NULL, w.State, h.State) AS State
FROM Persons AS p
JOIN Addresses AS w ON w.AddressID = p.WorkAddressID
LEFT JOIN Addresses as h ON h.AddressID = p.HomeAddressID
A self join would handle this:
select
p.personname,
case when ha.state is null then wa.street else ha.street end as street,
case when ha.state is null then wa.city else ha.city end as city,
case when ha.state is null then wa.state else ha.state end as state
from
Persons p
inner join addresses wa on p.workaddressid = wa.addressid
left join addresses ha on p.homeaddressid = ha.addressid
This syntax would be for MSSQL
Edit: changed the home to a left join because of the criterion Many rows in Persons table do not have HomeAddressID
I have three tables like this:
Person table:
person_id | name | dob
--------------------------------
1 | Naveed | 1988
2 | Ali | 1985
3 | Khan | 1987
4 | Rizwan | 1984
Address table:
address_id | street | city | state | country
----------------------------------------------------
1 | MAJ Road | Karachi | Sindh | Pakistan
2 | ABC Road | Multan | Punjab | Pakistan
3 | XYZ Road | Riyadh | SA | SA
Person_Address table:
person_id | address_id
----------------------
1 | 1
2 | 2
3 | 3
Now I want to get all records of Person_Address table but also with their person and address records like this by one query:
person_id| name | dob | address_id | street | city | state | country
----------------------------------------------------------------------------------
1 | Naveed | 1988 | 1 | MAJ Road | Karachi | Sindh | Pakistan
2 | Ali | 1985 | 2 | ABC Road | Multan | Punjab | Pakistan
3 | Khan | 1987 | 3 | XYZ Road | Riyadh | SA | SA
How it is possible using zend? Thanks
The reference guide is the best starting point to learn about Zend_Db_Select. Along with my example below, of course:
//$db is an instance of Zend_Db_Adapter_Abstract
$select = $db->select();
$select->from(array('p' => 'person'), array('person_id', 'name', 'dob'))
->join(array('pa' => 'Person_Address'), 'pa.person_id = p.person_id', array())
->join(array('a' => 'Address'), 'a.address_id = pa.address_id', array('address_id', 'street', 'city', 'state', 'country'));
It's then as simple as this to fetch a row:
$db->fetchRow($select);
In debugging Zend_Db_Select there's a clever trick you can use - simply print the select object, which in turn invokes the toString method to produce SQl:
echo $select; //prints SQL
I'm not sure if you're looking for SQL to do the above, or code using Zend's facilities. Given the presence of "sql" and "joins" in the tags, here's the SQL you'd need:
SELECT p.person_id, p.name, p.dob, a.address_id, street, city, state, country
FROM person p
INNER JOIN Person_Address pa ON pa.person_id = p.person_id
INNER JOIN Address a ON a.address_id = pa.address_id
Bear in mind that the Person_Address tells us that there's a many-to-many relationship between a Person and an Address. Many Persons may share an Address, and a Person may have more than one address.
The SQL above will show ALL such relationships. So if Naveed has two Address records, you will have two rows in the result set with person_id = 1.
Consider the following table structure with data -
AdjusterID | CompanyID | FirstName | LastName | EmailID
============================================================
1001 | Sterling | Jane | Stewart | janexxx#sterlin.com
1002 | Sterling | David | Boon | dav#sterlin.com
1003 | PHH | Irfan | Ahmed | irfan#phh.com
1004 | PHH | Rahul | Khanna | rahul#phh.com
============================================================
Where AdjusterID is the primary key. There are no. of adjusters for a company.
I need to have a query that will list single adjuster per company. i.e. I need to get the result as -
========================================================
1001 | Sterling | Jane | Stewart | janexxx#sterlin.com
1003 | PHH | Irfan | Ahmed | irfan#phh.com
========================================================
If any one could help me that will be great.
One way:
SELECT * FROM Adjusters
WHERE AdjusterID IN(SELECT min(AdjusterID)
FROM Adjusters GROUP BY CompanyID)
There are a handful of other ways involving unions and iteration, but this one is simple enough to get you started.
Edit: this assumes you want the adjuster with the lowest ID, as per your example
I know the answer from Jeremy is a valid one, so I will not repeat it. But you may try another one using a so called tie-breaker:
--//using a tie-breaker. Should be very fast on the PK field
--// but it would be good to have an index on CompanyID
SELECT t.*
FROM MyTable t
WHERE t.AdjusterID = (SELECT TOP 1 x.AdjusterID FROM MyTable x WHERE x.CompanyID = t.CompanyID ORDER BY AdjusterID)
It could be better performance-wise. But even more useful it is if you had another column in the table and you wanted to select not just one for each company but the best for each company using some other column ranking as a criteria. So instead of ORDER BY AdjusterID, you would order by that other column(s).