I have 2 tables in the following way
Table 1:
e_id e_name e_salary e_age e_gender e_dept
---------------------------------------------------
1 sam 95000 45 male operations
2 bob 80000 21 male support
3 ann 125000 25 female analyst
Table 2:
d_salary d_age d_gender e_dept
----------------------------------
34000 25 male Admin
56000 41 female Tech
77000 35 female HR
I want the output something like this:
e_id e_name e_salary e_age e_gender e_dept d_salary d_age d_gender e_dept
1 sam 95000 45 male operations 34000 25 male Admin
2 bob 80000 21 male support 56000 41 female Tech
3 ann 125000 25 female analysts 77000 35 female HR
There is no dependency between the tables. No common columns. No primary or foreign key.
I tried using cross join that results in duplicate rows because it works on M X N
I am new to this SQL thing. Can someone help me, please? Thanks in advance
Though I didn't get the reason behind your desired output but you can get that with below query:
select a.e_id ,a.e_name ,a.e_salary ,a.e_age ,a.e_gender ,a.e_dept,b.d_salary ,b.d_age ,b.d_gender ,b.e_dept
from
(select e_id ,e_name ,e_salary ,e_age ,e_gender ,e_dept, row_number()over(order by e_id)rn
from table1)a
inner join
(select d_salary d_age d_gender e_dept,row_number()over(order by d_salary) rn
from table 2) b
on a.rn=b.rn
Generally you can create a row count using the row_number() window function on both tables and use this as join criterion. But this requires a certain order for both tables, which means that you have explicitly tell the query why is the Admin record ordered first and must be joined on the first record of table 1:
SELECT
*
FROM (
SELECT
*,
row_number() OVER (ORDER BY e_id) as row_count -- assuming e_id is your order criterion
FROM table1
) t1
JOIN (
SELECT
*,
row_number() OVER (ORDER BY /*whatever you expect to be ordered*/) as row_count
FROM table2
) t2
ON t1.row_count = t2.row_count
Related
i'm introducing you the problem with DISTINCT values by column condition i have dealt with and can't provide
any idea how i can solve it.
So. The problem is i have two Stephen here declared , but i don't want duplicates:
**
The problem:
**
id vehicle_id worker_id user_type user_fullname
9 1 NULL external_users John Dalton
10 1 16 employees Mike
11 1 1 employees Stephen
12 2 173 employee Nicholas
13 2 1 employee Stephen
14 1 NULL external_users Peter
**
The desired output:**
id vehicle_id worker_id user_type user_fullname
9 1 NULL external_users John Dalton
10 1 16 employees Mike
12 2 173 employee Nicholas
13 2 1 employee Stephen
14 1 NULL external_users Peter
I have tried CASE statements but without success. When i group by it by worker_id,
it removes another duplicates, so i figured out it needs to be grouped by some special condition?
If anyone can provide me some hint how i can solve this problem , i will be very grateful.
Thank's!
There are no duplicate rows in this table. Just because Stephen appears twice doesn't make them duplicates because the ID, VEHICLE_ID, and USER_TYPE are different.
What you need to do is decide how you want to identify the Stephen record you wish to see in the output. Is it the one with the highest VEHICLE_ID? The "latest" record, i.e. the one with the highest ID?
You will use that rule in a window function to order the rows within your criteria, and then use that row number to filter down to the results you want. Something like this:
select id, vehicle_id, worker_id, user_type, user_fullname
from (
select id, vehicle_id, worker_id, user_type, user_fullname,
row_number() over (partition by worker_id, user_fullname order by id desc) n
from user_vehicle
) t
where t.n = 1
So, i have an task in uni to get max stipend in each faculty from a table with stipends.
Faculty table is:
ID_FACULTY FACULTY_NAME DEAN TELEPHON
---------- ------------------------------ -------------------- --------
10 Informacijas tehnologiju Vitols 63023095
11 Lauksaimniecibas Gaile 63022584
12 Tehniska Dukulis 53020762
13 Partikas tehnologijas Sabovics 63021075
Money table is:
ID_PAYOUT STUDENT_ID PAYOUT_DA STIPEND COMPENSATION
---------- ---------- --------- ---------- ------------
100 1 24-SEP-20 45.25 15
101 7 20-SEP-20 149.99 0
102 3 18-SEP-20 100 0
103 17 02-SEP-20 90.85 20
104 9 03-SEP-20 85 20
105 19 09-SEP-20 70.75 0
106 25 15-SEP-20 55 15
107 17 17-SEP-20 105.54 0
108 15 22-SEP-20 94 0
109 27 28-SEP-20 100 20
And the student table is:
ID_STUDENT SURNAME NAME COURSE_YEAR FACULTY_ID BIRTHDATE
---------- ------------------------- -------------------- ----------- ---------- ---------
1 Lapa Juris 4 13 27-SEP-96
3 Vilkauss Fredis 2 10 17-MAY-99
5 Karlsone Rasa 1 11 13-MAR-00
7 Grozitis Guntars 3 12 16-APR-97
9 Sonciks Jurgis 2 10 17-MAR-99
11 Berzajs Olafs 3 10 14-FEB-97
13 Vike Ilvija 2 13 14-MAY-99
15 Baure Inga 3 11 12-APR-97
17 Viskers Zigmunds 2 13 15-AUG-99
19 Talmanis Harijs 3 13 15-JUL-97
21 Livmanis Indulis 1 10 19-JAN-00
23 Shaveja Uva 2 13 18-FEB-98
25 Lacis Guntis 4 10 17-SEP-96
27 Liepa Guna 4 11 18-AUG-96
29 Klava Juris 2 10 19-MAY-98
I have tried many variations of queries, i think that I even tried all the possible combinations of joins, but i cannot achieve the neccessary result.
One of my queries looked like this:
SQL> SELECT ROW_NUMBER() OVER (ORDER BY surname) "Nr.",
f.faculty_name,
s.surname,
s.name,
MAX(m.stipend)
FROM faculty f, student s INNER JOIN money m ON s.id_student = m.student_id
WHERE s.faculty_id = f.id_faculty
GROUP BY f.faculty_name, s.surname, s.name
ORDER BY s.surname;
Which returned me the following result:
Nr. FACULTY_NAME SURNAME NAME MAX(M.STIPEND)
---------- ------------------------------ ------------------------- -------------------- --------------
1 Lauksaimniecibas Baure Inga 94
2 Tehniska Grozitis Guntars 149.99
3 Informacijas tehnologiju Lacis Guntis 55
4 Partikas tehnologijas Lapa Juris 45.25
5 Lauksaimniecibas Liepa Guna 100
6 Informacijas tehnologiju Sonciks Jurgis 85
7 Partikas tehnologijas Talmanis Harijs 70.75
8 Informacijas tehnologiju Vilkauss Fredis 100
9 Partikas tehnologijas Viskers Zigmunds 105.54
9 rows selected.
So the goal of this task is to retrieve the maximum amount of stipend granted to a student in a certain faculty.
Can someone please tell what am I doing wrong here?
Just max amount per faculty:
SELECT
f.faculty_name,
MAX(m.stipend)
FROM
faculty f
INNER JOIN student s ON s.faculty_id = f.id_faculty
INNER JOIN money m ON s.id_student = m.student_id
GROUP BY f.faculty_name
Max amount and all other details too:
SELECT * FROM
(
SELECT
ROW_NUMBER() OVER (PARTITION BY f.faculty_name ORDER BY m.stipend desc) rn,
f.*,
s.*,
m.*
FROM
faculty f
INNER JOIN student s ON s.faculty_id = f.id_faculty
INNER JOIN money m ON s.id_student = m.student_id
) x
WHERE x.rn = 1
Points of note:
Do not use old style joins; if you ever write one table_name, other_table_name in a FROM block, you're using old style joins. Don't do it; they became bad news about 30 years ago
When you have a max-n-per-group, you specify how finely detailed the group is. If you GROUP BY s.first_name, s.last_name, f.faculty_name then your groups are "every unique combination of firstname/lastname/faculty, so the only way you'll get multiple items in your group is if there are two John Smiths in Mathematics. If the group is to be the whole of mathematics, then the faculty name (and anything else that is uniquely related 1:1 to it, like the faculty ID) is all that you can put in your group. Anything not in a group must be in an aggregation, like MAX
When you want other details too, you either group and max the data and then join this groupmaxed data back to the original data to use it as a filter, or you use an approach like here where you use a row_number or rank, with a partition (which is like an autojoined grouped summary). There is no group here; the row numbering acts like a group because it restarts from 1 every different faculty and proceeds incrementally as stipend decreses. This means that the highest stipend is always in row number 1.
Unlike using a groupmax that you join back to get the detail, the row_number route does not produce duplicate rows with tied-for-highest stipends
I have one database and time to time i change some part of query as per requirement.
i want to keep record of results of both before and after result of these queries in one table and want to show queries which generate difference.
For Example,
Consider following table
emp_id country salary
---------------------
1 usa 1000
2 uk 2500
3 uk 1200
4 usa 3500
5 usa 4000
6 uk 1100
Now, my before query is :
Before Query:
select count(emp_id) as count,country from table where salary>2000 group by country;
Before Result:
count country
2 usa
1 uk
After Query:
select count(emp_id) as count,country from table where salary<2000 group by country;
After Query Result:
count country
2 uk
1 usa
My Final Result or Table I want is:
column 1 | column 2 | column 3 | column 4 |
2 usa 2 uk
1 uk 1 usa
...... but if query results are same than it shouldn't show in this table.
Thanks in advance.
I believe that you can use the same approach as here.
select t1.*, t2.* -- if you need specific columns without rn than you have to list them here
from
(
select t.*, row_number() over (order by count) rn
from
(
-- query #1
select count(emp_id) as count,country from table where salary>2000 group by country;
) t
) t1
full join
(
select t.*, row_number() over (order by count) rn
from
(
-- query #2
select count(emp_id) as count,country from table where salary<2000 group by country;
) t
) t2 on t1.rn = t2.rn
I am working with duplicating multiple records in table 1 with primary key which has a reference with table 2 (foreign key)
Consider table employee with columns (eid(primary key),ename,dept,dept_code).
Table 2 employee_address with columns (eaid(primary key), eid(foreign key), city, country)
Now the task is the table 1 (ie. employee) may have number of values with different department codes.
Suppose dept_code may be 1 or 2 like so and so.
Now with both the table with some data look like this
EMPLOYEE table
Eid(pk) ename dept Dept_code
100 Sss Cse 1
101 Aaa Cse 1
102 Bbb Cse 1
103 Ccc Eee 2
104 ddd it 3
EMPLOYEE ADDRESS table
Eaid (pk) Eid (fk) city country
1 100 NY Us
2 100 NY Us
3 100 NY Us
4 101 CALIF Us
5 102 DC Us
6 102 DC Us
7 103 NJ Us
now the thing is i have to duplicate all the records in employee table where dept_code=1 and duplicate records dept_code should be = 5.
And the foreign key referencing to employee address table (ie. here in the current document 100,101,102) in the table 2 has to be duplicated number of times those foreign key value present in table 2.
I have to get the output like this
Employee table
Eid(pk) ename dept Dept_code
100 Sss Cse 1
101 Aaa Cse 1
102 Bbb Cse 1
103 Ccc Eee 2
104 ddd it 3
**105 sss cse 5
106 aaa cse 5
107 bbb cse 5**
Employee Address table
Eaid (pk) Eid (fk) city country
1 100 NY Us
2 100 NY Us
3 100 NY Us
4 101 CALIF Us
5 102 DC Us
6 102 DC Us
7 103 NJ Us
**8 105 NY Us
9 105 NY Us
10 105 Ny Us
11 106 CALIF Us
12 107 DC Us
13 107 DC Us**
Now I have to get the output like this.
Conditions for this task is,
no for loop
hitting a database should be as minimal as possible
can use java or if posssible in sql query itself.
I tried with various ideas nothing worked out.
Help me out in this.
If I understand your question, these two queries will work. They use tSql window functions, if you are not using Sql Server then you will need to find the equivalent.
Edited to answer comment from OP-
If you want to create new tables:
Select * Into EmployeeNew From (
Select *
From Employee E
Union All
Select Row_Number() Over (Order By eid) + (Select Max(eid) From Employee),
ename, dept, 5 dept_code
From Employee
Where Dept_Code = 1) A
Select * Into EmployeeAddressNew From (
Select A.*
From Employee E
Join EmployeeAddress A On A.eid = E.eid
Union All
Select A.eaid + (Select Max(eaid) From EmployeeAddress),
Dense_Rank() Over (Order By E.eid) + (Select Max(eid) From Employee),
City, Country
From Employee E
Join EmployeeAddress A On A.eid = E.eid
Where E.Dept_Code = 1) A
If you only want to insert 'new' records into the original tables:
Insert Employee
Select Row_Number() Over (Order By eid) + (Select Max(eid) From Employee),
ename, dept, 5 dept_code
From Employee
Where Dept_Code = 1
Insert EmployeeAddress
Select A.eaid + (Select Max(eaid) From EmployeeAddress),
Dense_Rank() Over (Order By E.eid) + (Select Max(eid) From Employee),
City, Country
From Employee E
Join EmployeeAddress A On A.eid = E.eid
Where E.Dept_Code = 1
I have a requirement in such a way that it should join two tables with more than 100k records in one table and just 5 records in another table as shown below
Employee Dept Result
id Name deptid deptid Name Name deptid Name
1 Jane 1 1 Science Jane 1 Science
2 Jack 2 2 Maths Dane 1 Science
3 Dane 1 3 Biology Jack 2 Maths
4 Drack 3 4 Social Drack 3 Biology
5 Drim 5 Zoology Kery 4 Social
6 Drum 5 Drum 5 Zoology
7 Krack
8 Kery 4
.
.
100k
Which join need to be used to get the query in an better way to perform to get the result as shown.
I just want the query to join with other table from employee table only which has dept which i thought of below query but wanted to know is there any better way to do it.
Select e.name,d.deptid,d.Name from
(Select deptid,Name from Employee where deptid IS NOT NULL) A
and dept d where A.deptid=d.deptid;
Firstly not sure why you are performing your query the way you are. Should be more like
SELECT A.name, D.deptid,D.Name
FROM Employee A
INNER JOIN dept D
ON A.deptid = D.deptid
No need of the IS NOT NULL statement.
If this is a ONE TIME or OCCASIONAL thing and performance is key (not a permanent query in your DB) you can leave out the join altogether and do it using CASE:
SELECT
A.name, A.deptid,
CASE
WHEN A.deptid = 1 THEN "Science"
WHEN A.deptid = 2 THEN "Maths"
...[etc for the other 3 departments]...
END as Name
FROM Employee A
If this is to be permanent and performance is key, simply try applying an INDEX on the foreign key deptid in the Employee table and use my first query above.