I have a staff database table containing staff members, with user_no and user_name columns. I have another, department, table containing the departments which staff can be members of, with dept_no and dept_name as columns.
Because staff can be members of multiple departments, I have a third, staff_dept, table with a user_no column and a dept_no column, which are the primary keys of those other two tables. This table shows which departments each member of staff belongs to and contains one row for each user/department intersection.
I would like to have an output in the form of a spreadsheet (CSV file, whatever; I'll be fine mangling the results into a usable form after I've got them) with one column for each department, and one row for each user, with an X appearing at each intersection, as defined in staff_dept.
Can I write a single SQL query which will achieve this result? or will I have to do some "real" programming (because it's not a "real" program until you've nested three or four for loops, obviously) to collect and format this data?
This can be done with a PIVOT table (using SQL Server):
SELECT user_name, [dept1name], [dept2name], [dept3name], ...
FROM
(SELECT s.user_name, d.dept_name,
case when sd.user_no is not null then 'X' else '' end as matches
from staff s
cross join department d
left join staff_dept sd on s.user_no = sd.user_no and d.dept_no = sd.dept_no
) AS s
PIVOT
(
min(matches)
FOR dept_name IN ([dept1name], [dept2name], [dept3name], ...)
) AS pvt
order by user_name
Demo: http://www.sqlfiddle.com/#!3/c136d/5
Edit: To generate the PIVOT query dynamically from the list of departments in the table, you would make use of dynamic SQL, i.e., generate the code into a variable and use sp_executesql helper stored procedure. Here's an example: http://www.sqlfiddle.com/#!3/c136d/14
In SQL Server (if you're using SQL Server), I would start with a full outer join (to include all staff and departments, not just those involved in the relation), drop that into a pivot statement to pivot all departments into columns, and then build a short script to generate and dynamically execute that SELECT statement (because the columns created by a pivot statement must be hard-coded, they can't be dynamically generated at run time).
Here's a sample -- it's an unpivot statement, but the concept is pretty much the same.
Related
To create a many-to-many relationship, I have three tables:
tblEmployee, contains employees
tlkpPermission, contains 11 different possible permission groups an employee can be part of
tblEmployeeXPermission, combines the EmployeeID with one or more PermissionID
What I’m trying to create is a query that shows what permission groups an employee is NOT part of.
So, if EmployeeID 12345 is associated with PermissionID 1,2,3,4,5, but NOT 6,7,8,9,10,11 (in the EmployeeXPermission table) then I want the query to show EmployeeID 12345 is not part of PermissionID 6,7,8,9,10,11.
Of all the JOINs and query options, I can only get a query to show which PermissionIDs an employee is associated with, but not the PermissionIDs the employee is not associated with.
Any help would be appreciated.
Thanks
You need to start with all combinations of employees and permissions, and this type of join is CROSS JOIN, but MsAccess SQL does not have it in the new SQL syntax. You can use the old syntax of listing your tables in the FROM clause, comma separated, and provide the join condition, if any, in the WHERE clause:
SELECT
EmployeeId,
PermissionID
FROM
tblEmployee as E,
tlkpPermission as P
where not exists (
select 1
from tblEmployeeXPermission X
where X.EmployeeId=E.EmployeeId
and X.PermissionId=P.PermissionId
)
Here the part up to the WHERE clause would give you all employee - permission combinations, and the WHERE clause removes those occuring in the tblEmployeeXPermission, leaving you with the ones you want.
I have two different tables with records I need to join together in a way I can't quite figure out how to make work. My data looks like this.
Table A
Columns: Employee_ID, Employee_Department, Employee_Team, Manager_ID, Is_a_Manager ... many other columns
Sample Values:
12345 Department1 Team1 67890 Yes/No
.
.
.
One employee per row, several thousand rows comprising the entire company
Table B
Employee_ID, Manager_ID ... other columns
The exact same data set as Table A
Currently I'm combining those two tables (and three others) with a simple join on Employee_ID, which I'm then using as a data source in Tableau to visualize the data.
What I'd like to do with a SQL script is as follows:
Check to see whether an employee in Table A is a manager or not based on the Is_a_Manager column
If they are, find an employee in Table B who is one of their direct reports by matching the employee ID in Table A to the Manager ID in Table B.
Lookup that direct report's department and team in Table A by matching the Employee_ID in Table B to Employee_ID in Table A and displaying the Employee_Department and Employee_Team columns.
Add the direct report's department and team to two new columns in the original manager's Table A row
I'd like the final output in Table A to be something like
Employee_ID, Employee_Department, Employee_Team, Manager_ID, Is_a_Manager? ... Direct_Report_Department, Direct_Report_Team
Also, an important point is that some managers will have employees who are on different teams, so values in the Direct_Report_Department and Direct_Report_Team are not distinct. I only actually need any one employee's Department and Team to display, it doesn't matter which employee's it is.
Finally, I am able to do step 1 fairly easily in Tableau, so if the SQL script could do steps 2-4 and simply return a null value if the employee was not a manager, that would work for me as well.
Any ideas on how to accomplish this would be greatly appreciated. Thank you!
This should work based on the requirement provided. You don’t have to do any of the steps in Tableau and can simply export the output from the SQL as your data source
Select Tb1.Employee_ID, Tb1.Employee_Department, Tb1.Employee_Team, Tb1.Manager_ID, Tb1.Is_a_Manager, Tb3. Direct_Report_Department, Tb3. Direct_Report_Team
from Table_A Tb1
join (Select Manager_id, max(Employee_id) as emp_id from Table_B group by Manager_id) Tb2
on Tb1.Employee_id = Tb2.Manager_id
left join (Select Employee_ID, Employee_Department as Direct_Report_Department, Employee_Team as Direct_Report_Team from Table_A group by Employee_ID, Employee_Department, Employee_Team) Tb3
on Tb2.emp_id = Tb3.Employee_ID
where Tb1.Is_a_Manager = 'Yes';
Hi i am using oracle sqlplus on the sample HR database tables.
I have 2 tables, employees and jobs in which i have job_id in both of them.
I want to be able to enter the input of the job_ID and then it displays the first_name, last_name (which is inside employees table)
I am new to sql and learning. Thanks in advance
When you want to query data out of an SQL Database, you need the SELECT Statement. In your case, that would be:
SELECT first_name, last_name FROM Employees WHERE job_ID=:job_ID;
SELECT ... Keyword of "SELECT" Statements
firstname, lastname ... Columns you want the query to return
FROM Employees ... Keyword + Tablename you want to query on
WHERE job_ID=:job_ID ... Condition which will be used to select specific rows
:job_ID ... Your input of which job_ID you want to get
Your searched Query was the userinput mixed with the Jobs:
SELECT first_name, last_name FROM Employees JOIN Jobs ON Employees.job_ID=Jobs.job_ID WHERE Jobs.min_salary=&min_salary AND Jobs.max_salary=&max_salary;
JOIN Combines the rows of each table to one bigger table, there are many different types of them, this is just the basic one
ON Gives the JOIN the parameter to check whether this column is the same in two rows of each table. If yes, they will be merged
I am trying to display employee properties using C# WPF view.
I have data in '2' different oracle tables in my database:
Those tables structure at high-level is...
Employee table (EMP) - columns:
ID, Name, Organisation
Employee properties table (EMPPR) - columns
ID, PropertyName, PropertyValue
The user will input 'List of Employee Name' and I need to display Employee properties using data in those '2' tables.
Each employee has properties from 40-80 i.e. 40-80 rows per employee in EMPPR table. In this case, which approach is more efficient?
Approach #1 - single query data retrieval:
SELECT Pr.PropertyName, Pr.PropertyValue
FROM EMP Emp, EMPPR Pr
WHERE Emp.ID = Pr.ID
AND Emp.Name IN (<List of Names entered>)
Approach #2 - get IDs list using one query and Get properties using that ID in the second query
Query #1:
SELECT ID
FROM EMP
WHERE Name IN (<List of Names entered>)
Query #2:
SELECT PropertyName, PropertyValue
FROM EMPPR
WHERE ID IN (<List of IDs got from Query#1>)
I need to retrieve ~10K employee details at once where each employee has 40-80 properties.
Which approach is good?
Which query is faster?
The first one, which uses a single query to fetch your results.
Why? much of the elapsed time handling queries, especially ones with modestly sized rows like yours, is consumed going back and forth from the client to the database server.
Plus, the construct WHERE something IN (val, val, val, val ... ... val) can throw an error when you have too many values. So the first query is more robust.
Pro tip: Come on into the 21st century and use the new JOIN syntax.
SELECT Pr.PropertyName, Pr.PropertyValue
FROM EMP Emp
JOIN EMPPR Pr ON Emp.ID = Pr.ID
WHERE Emp.Name IN (<List of Names Inputted>)
Use first approach of join between two tables which is far better than using where clause two times.
I am still learning the ropes of SQL so I have run into my first obstacle. I am to create an SQL query that retrieves employee.firstname, employee.lastname, dependents.depname, and dependents.birthday from the two tables employees and dependents.
I am only supposed to show an employee if he or she has a dependent.
My primary table (employee; only the first 43 rows): employee table
My secondary table (dependents): dependents table
This is what I have so far:
SELECT
employee.firstname, employee.lastname,
dependents.depname, dependents.birthday
FROM
employee
INNER JOIN
dependents ON employee.id = dependents.empid
This works fine however I run into many duplicate rows of data:
Original Query
This is not the full query result but I think it provides sufficient evidence of my problem.
I used the DISTINCT keyword with my SELECT statement, but it only retrieved a small number of my dependents.
Adding DISTINCT
Have you already any duplicates in one of the tables employee or dependents? The second result looks correct. With select distinct the database removes all duplicates from the result set.