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
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';
so I've been struggling with some of the select statements on multiple tables:
Employee table
Employee_ID
First_Name
Last_Name
Assignment table
Assignment_ID
Employee_ID
Host_Country_arrival_Date
Host_Country_departure_Date
Scheduled_End_Date
I'm being asked to display query to display employee full name, number of days between the host country arrival date and host country departure date, number of days between today's date and the assignment scheduled end date and the results sorted according to host country arrival date with the oldest date on top.
also, I'm not familiar with the sort function in SQL server..
Here's my query and I've been getting syntax errors:
SELECT
First_Name
Last_Name
FROM Employee
SELECT
Host_Country_Arrival_Date
Host_Country_Departure_Date
FROM Assignment;
So, Basically what your code is doing is 2 different queries. The first getting all the employees names, and the second one getting the dates of the assignments.
What you'll want to do here is take advantage of the relationship between the tables using a JOIN. That is basically saying "Give me all employees and all of HIS/HERS assignments". So, for each assignment that the employee has, it will bring a row in the result with his name and the assignment info.
To get the difference between days you use DATEDIFF passing 3 parameters, the timespan in which to calculate the difference, the first and the second date. It will then Subtract the first one from the second one and give you the result in the selected timespan.
And finnaly the sorting: Just add 'ORDER BY' followed by each column that you want to use for ordering and then specify if you want it ascending (ASC) or descending (DESC).
You can check how I would answer the if that question was proposed to me in a coding challenge.
SELECT
CONCAT(E.First_Name,' ', E.Last_Name) FullName,
DATEDIFF(DAY,Scheduled_End_Date,getdate()) DaysTillScheduledDate,
DATEDIFF(DAY,Host_Country_Arrival_Date,Host_Country_Departure_Date) DaysTillScheduledDate
FROM Employee As E --Is nice to add aliases
Inner Join
Assignment As A
on E.Employee_ID = A.Employee_ID -- Read a little bit about joins, there are a lot of material availabel an its going to be really necessary moving forward with SQL
order by Host_Country_Arrival_Date DESC -- Just put the field that you want to order by here, desc indicates that it should be descending
You should use a JOIN to link the tables together on Employee_ID:
SELECT
First_Name,
Last_Name,
Host_Country_Arrival_Date,
Host_Country_Departure_Date
FROM Employee
JOIN Assignment ON Assignment.Employee_ID = Employee.Employee_ID;
What this is saying basically is that for each employee, go out to the assignments table and add the assignments for that employee. If there are multiple assignments, the employee columns will be repeated on each row with the assignment columns for the assignment.
You need to look for the join and group by. Please find this link for reference tutorial
For now you may try this...
SELECT
CONCAT(Emp.First_Name,' ', Emp.Last_Name) FullName,
DATEDIFF(DAY,Scheduled_End_Date,getdate()) DaysTillScheduledDate,
DATEDIFF(DAY,Host_Country_Arrival_Date,Host_Country_Departure_Date) DaysTillScheduledDate
FROM Employee As Emp Inner Join Assignment As Assign on Emp.Employee_ID = Assign.Employee_ID
order by Host_Country_Arrival_Date DESC
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.
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.