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).
Related
I am using Microsoft Access and in it, I have a table with data that is sometimes repeated. I'm not able to create an SQL query that removes duplicate data, leaving only distinct data in the table. Can someone help me?
My current table:
Date | Level | Name
---------+--------+--------
12/25/2021 | 2 | Jack
12/25/2021 | 2 | Jack
12/10/2021 | 3 | Ana
12/01/2021 | 1 | Lenon
12/01/2021 | 1 | Lenon
12/30/2021 | 3 | Ana
Expected result:
Date | Level | Name
---------+--------+--------
12/25/2021 | 2 | Jack
12/10/2021 | 3 | Ana
12/01/2021 | 1 | Lenon
12/30/2021 | 3 | Ana
PS: Ana appears twice in the expected result table because the dates of the two rows referring to Ana are different, so they are not duplicated values.
Just use select distinct:
select distinct t.*
from t;
I would add that tables should not have duplicate rows. Something is wrong with the table generation if you are getting duplicates -- either the query being used or the process for inserting rows into the table.
You can do a group by of the Date, Level and Name columns.
Use this query:
SELECT Date
,Level
,Name
FROM <TableName>
GROUP BY Date, Level, Name
EDIT
I've edited this question to make it a little more concise, if you see my edit history you will see my effort and 'what I've tried' but it was adding a lot of unnecessary noise and causing confusion so here is a summary of input and output:
People:
ID | FullName
--------------------
1 | Jimmy
2 | John
3 | Becky
PeopleJobRequirements:
ID | PersonId | Title
--------------------
1 | 1 | Some Requirement
2 | 1 | Another Requirement
3 | 2 | Some Requirement
4 | 3 | Another Requirement
Output:
FullName | RequirementTitle
---------------------------
Jimmy | Some Requirement
Jimmy | Another Requirement
John | Some Requirement
John | null
Becky | null
Becky | Another Requirement
Each person has 2 records, because that's how many distinct requirements there are in the table (distinct based on 'Title').
Assume there is no third table - the 'PeopleJobRequirements' is unique to each person (one person to many requirements), but there will be duplicate Titles in there (some people have the same job requirements).
Sincere apologies for any confusion caused by the recent updates.
CROSS JOIN to get equal record for each person and LEFT JOIN for matching records.
Following query should work in your scenario
select p.Id, p.FullName,r.Title
FROM People p
cross join (select distinct title from PeopleJobRequirements ) pj
left join PeopleJobRequirements r on p.id=r.personid and pj.Title=r.Title
order by fullname
Online Demo
Output
+----+----------+---------------------+
| Id | FullName | Title |
+----+----------+---------------------+
| 3 | Becky | Another Requirement |
+----+----------+---------------------+
| 3 | Becky | NULL |
+----+----------+---------------------+
| 1 | Jimmy | Some Requirement |
+----+----------+---------------------+
| 1 | Jimmy | Another Requirement |
+----+----------+---------------------+
| 2 | John | NULL |
+----+----------+---------------------+
| 2 | John | Some Requirement |
+----+----------+---------------------+
use left join, no need any subquery
select p.*,jr.*,jrr.*
from People p left join
PeopleJobRequirements jr on p.Id=jrPersonId
left join JobRoleRequirements jrr p.id=jrr.PersonId
according the explanation, People and PeopleJobRequirements tables have many to many relationship (n to n).
so first of all you'll need another table to relate these to table.
first do this and then a full join will make it right.
I am currently trying to SELECT the DISTINCT FirstNames in a GROUP, using Microsoft Access 2010.
The simplified relevant columns of my table looks like this:
+----+-------------+-----------+
| ID | GroupNumber | FirstName |
+----+-------------+-----------+
| 1 | 1 | Peter |
| 2 | 1 | Bob |
| 3 | 1 | Peter |
| 4 | 2 | Rosemary |
| 5 | 2 | Jamie |
| 6 | 3 | Peter |
+----+-------------+-----------+
My actual table contains two columns to which I want to apply this process (separately), but I should be able to simply repeat the process for the other column. The column group number is a simplification, my table actually groups all rows in a ten day interval together, but I've already solved that problem.
And I would like it to return this:
+-------------+------------+
| GroupNumber | FirstNames |
+-------------+------------+
| 1 | Peter |
| 1 | Bob |
| 2 | Rosemary |
| 2 | Jamie |
| 3 | Peter |
+-------------+------------+
This means that I want all Distinct FirstNames for each Group.
A regular DISTINCT would ignore group boundaries and only mention Peter once. All aggregate functions reduce my output to only one value or don't work on strings at all. Access also doesn't support SELECTing columns that are not aggregates or in the GROUP BY statement.
All other answers I've found either want an aggregate, are not applicable to MS Access or are solved by working around the data in ways not applicable to my case. (Standardized languages are a nice thing, aren't they?)
My current (invalid) query looks like this:
SELECT GroupNumber,
DISTINCT FirstNames -- This is illegal, distinct applies to all
-- columns and doesn't respect groups.
FROM Example AS b
-- Complicated stuff to make the groups
GROUP BY GroupNumber;
This query is a one time thing and is used to analyze a 58000 row excel spreadsheet exported from another Database (not my fault), so optimizing for runtime is not necessary.
I would like to achieve this purely through SQL and without VBA if at all possible.
This should work:
SELECT DISTINCT GroupNumber, FirstNames
FROM Example AS b
A solution for this problem would be group by the columns GroupNumber and FirstNames at the same time. The query is presented below:
Select GroupNumber, FirstNames
From input
Group By GroupNumber, FirstNames
(Standardized languages are a nice thing, aren't they?)
My specific use case is that I want to sort a list of users by name; first name, last name. The user has a preferred name and a legal name. I want to order by the preferred name if it is present, but the legal name as fall back.
For example, given the follow table:
id | first_name | last_name | preferred_first_name | preferred_last_name
----+------------+-----------+----------------------+---------------------
9 | Ryan | Bently | Alan |
10 | Ryan | Do | Billy | Baxter
11 | Olga | Clancierz | |
12 | Anurag | Plaxty | | Henderson
13 | Sander | Cliff | Billy |
I want to sort like this:
Alan Bently
Anurag Henderson
Billy Baxter
Billy Cliff
Olga Clancierz
Normally, with just one name set of name fields I would just do this:
SELECT * from users ORDER BY users.first_name, users.last_name
What is the best way to order by preferred name fields when present, but fall back to other name fields when they are not present?
Try
ORDER BY COALESCE(users.preferred_first_name,users.first_name), users.last_name
I guess this query is a little basic and I should know more about SQL but haven't done much with joins yet which I guess is the solution here.
What I have is a table of people and a table of job roles they hold. A person can have multiple jobs and I wish to have one set of results with a row per person containing their details and their job roles.
Two example tables (people and job_roles) are below so you can understand the question easier.
People
id | name | email_address | phone_number
1 | paul | paul#example.com | 123456
2 | bob | bob#example.com | 567891
3 | bart | bart#example.com | 987561
job_roles
id | person_id | job_title | department
1 | 1 | secretary | hr
2 | 1 | assistant | media
3 | 2 | manager | IT
4 | 3 | finance clerk | finance
4 | 3 | manager | IT
so that I can output each person and their roles like such
Name: paul
Email Address: paul#example.com
Phone: 123456
Job Roles:
Secretary for HR department
Assistant for media department
_______
Name: bob
Email address: bob#example.com
Phone: 567891
Job roles:
Manager for IT department
So how would I get each persons information (from the people table) along with their job details (from the job_roles table) to output like the example above. I guess it would be some kind of way of merging their jobs and their relevant departments into a jobs column that can be split up for output, but maybe there is a better way and what would the sql look like?
Thanks
Paul
PS it would be a mySQL database if that makes any difference
It looks like a straight-forward join:
SELECT p.*, j.*
FROM People AS p INNER JOIN Roles AS r ON p.id = r.person_id
ORDER BY p.name;
The remainder of the work is formatting; that's best done by a report package.
Thanks for the quick response, that seems a good start but you get multiple rows per person like (you have to imagine this is a table as you don't seem to be able to format in comments):
id | Name | email_address | phone_number | job_role | department
1 | paul | paul#example.com | 123456 | secretary | HR
1 | paul | paul#example.com | 123456 | assistant | media
2 | bob | bob#example.com | 567891 | manager | IT
I would like one row per person ideally with all their job roles in it if that's possible?
It depends on your DBMS, but most available ones do not support RVAs - relation-valued attributes. What you'd like is to have the job role and department part of the result like a table associated with the user:
+----+------+------------------+--------------+------------------------+
| id | Name | email_address | phone_number | dept_role |
+----+------+------------------+--------------+------------------------+
| | | | | +--------------------+ |
| | | | | | job_role | dept | |
| 1 | paul | paul#example.com | 123456 | | secretary | HR | |
| | | | | | assistant | media | |
| | | | | +--------------------+ |
+----+------+------------------+--------------+------------------------+
| | | | | +--------------------+ |
| | | | | | job_role | dept | |
| 2 | bob | bob#example.com | 567891 | | manager | IT | |
| | | | | +--------------------+ |
+----+------+------------------+--------------+------------------------+
This accurately represents the information you want, but is not usually an option.
So, what happens next depends on your report generation tool. Using the one I'm most familiar with, (Informix ACE, part of Informix SQL, available from IBM for use with the Informix DBMSs), you would simply ensure that the data is sorted and then print the name, email address and phone number in the 'BEFORE GROUP OF id' section of the report, and in the 'ON EVERY ROW' section you would process (print) just the role and department information.
It is often a good idea to separate the report formatting from the data retrieval operations; this is an example of where it is necessary unless your DBMS has unusual features to help with the formatting of selected data.
Oh dear that sounds very complicated and not something I could run easily on a mySQL database in a PHP page?
The RVA stuff - you're right, that is not for MySQL and PHP.
On the other hand, there are millions of reports (meaning results from queries that are formatted for presentation to a user) that do roughly this. The technical term for them is 'Control-Break Report', but the basic idea is not hard.
You keep a record of the 'id' number you last processed - you can initialize that to -1 or 0.
When the current record has a different id number from the previous number, then you have a new user and you need to start a new set of output lines for the new user and print the name, email address and phone number (and change the last processed id number). When the current record has the same id number, then all you do is process the job role and department information (not the name, email address and phone number). The 'break' occurs when the id number changes. With a single level of control-break, it is not hard; if you have 4 or 5 levels, you have to do more work, and that's why there are reporting packages to handle it.
So, it is not hard - it just requires a little care.
RE:
I was hoping SQL could do something
clever and join the rows together
nicely so I had essentially a jobs
column with that persons jobs in it.
You can get fairly close with
SELECT p.id, p.name, p.email_address, p.phone_number,
group_concat(concat(job_title, ' for ', department, ' department') SEPARATOR '\n') AS JobRoles
FROM People AS p
INNER JOIN job_roles AS r ON p.id = r.person_id
GROUP BY p.id, p.name, p.email_address, p.phone_number
ORDER BY p.name;
Doing it the way you're wanting would mean the result set arrays could have infinite columns, which would be very messy. for example, you could left join the jobs table 10 times and get job1, job2, .. job10.
I would do a single join, then use PHP to check if the name ID is the same from 1 row to the next.
One way might be to left outer join the tables and then load them up into an array using
$people_array =array();
while($row1=mysql_fetch_assoc($extract1)){
$people_array[] = $row1;
}
and then loop through using
for ($x=0;$x<=sizeof($people_array;)
{
echo $people_array[$x][id];
echo $people_array[$x][name];
for($y=0;$y<=$number_of_roles;$y++)
{
echo $people_array[$x][email_address];
echo $people_array[$x][phone_number];
$x++;
}
}
You might have to play with the query a bit and the loops but it should do generally what you want.For it to work as above every person would have to have the same number of roles, but you may be able to fill in the blanks in your table