I have created 2 tables as follows :
CREATE TABLE emp_bio(name VARCHAR2(15) NOT NULL ,id NUMBER, DOB DATE,PRIMARY KEY(id));
CREATE TABLE emp_sal(id NUMBER REFERENCES emp_bio(id), salary NUMBER,PRIMARY KEY(id));
Now, when I query as,
SELECT emp_sal.salary,emp_bio.name
FROM emp_sal right join emp_bio on emp_sal.id=emp_sal;
I get duplicate values in the output. Can anyone help me to remove that duplicate values !? Thank you.
You want to do a JOIN on both tables using both tables' id columns, since they're the ones relating both tables:
SELECT
eb.name,
es.salary
FROM emp_bio AS eb
INNER JOIN emp_sal AS es
ON es.id = eb.id
Related
I am learning SQL (postgres) and am trying to insert a record into a table that references records from two other tables, as foreign keys.
Below is the syntax I am using for creating the tables and records:
-- Create a person table + insert single row
CREATE TABLE person (
pname VARCHAR(255) NOT NULL,
PRIMARY KEY (pname)
);
INSERT INTO person VALUES ('personOne');
-- Create a city table + insert single row
CREATE TABLE city (
cname VARCHAR(255) NOT NULL,
PRIMARY KEY (cname)
);
INSERT INTO city VALUES ('cityOne');
-- Create a employee table w/ForeignKey reference
CREATE TABLE employee (
ename VARCHAR(255) REFERENCES person(pname) NOT NULL,
ecity VARCHAR(255) REFERENCES city(cname) NOT NULL,
PRIMARY KEY(ename, ecity)
);
-- create employee entry referencing existing records
INSERT INTO employee VALUES(
SELECT pname FROM person
WHERE pname='personOne' AND <-- ISSUE
SELECT cname FROM city
WHERE cname='cityOne
);
Notice in the last block of code, where I'm doing an INSERT into the employee table, I don't know how to string together multiple SELECT sub-queries to get both the existing records from the person and city table such that I can create a new employee entry with attributes as such:
ename='personOne'
ecity='cityOne'
The textbook I have for class doesn't dive into sub-queries like this and I can't find any examples similar enough to mine such that I can understand how to adapt them for this use case.
Insight will be much appreciated.
There doesn’t appear to be any obvious relationship between city and person which will make your life hard
The general pattern for turning a select that has two base tables giving info, into an insert is:
INSERT INTO table(column,list,here)
SELECT column,list,here
FROM
a
JOIN b ON a.x = b.y
In your case there isn’t really anything to join on because your one-column tables have no column in common. Provide eg a cityname in Person (because it seems more likely that one city has many person) then you can do
INSERT INTO employee(personname,cityname)
SELECT p.pname, c.cname
FROM
person p
JOIN city c ON p.cityname = c.cname
But even then, the tables are related between themselves and don’t need the third table so it’s perhaps something of an academic exercise only, not something you’d do in the real world
If you just want to mix every person with every city you can do:
INSERT INTO employee(personname,cityname)
SELECT pname, cname
FROM
person p
CROSS JOIN city c
But be warned, two people and two cities will cause 4 rows to be inserted, and so on (20 people and 40 cities, 800 rows. Fairly useless imho)
However, I trust that the general pattern shown first will suffice for your learning; write a SELECT that shows the data you want to insert, then simply write INSERT INTO table(columns) above it. The number of columns inserted to must match the number of columns selected. Don’t forget that you can select fixed values if no column from the query has the info (INSERT INTO X(p,c,age) SELECT personname, cityname, 23 FROM ...)
The following will work for you:
INSERT INTO employee
SELECT pname, cname FROM person, city
WHERE pname='personOne' AND cname='cityOne';
This is a cross join producing a cartesian product of the two tables (since there is nothing to link the two). It reads slightly oddly, given that you could just as easily have inserted the values directly. But I assume this is because it is a learning exercise.
Please note that there is a typo in your create employee. You are missing a comma before the primary key.
I have four tables
create table emp (emp_ss int, emp_name nvarchar(20));
create table comp(comp_name nvarchar(20), comp_address nvarchar(20));
create table works (emp_ss int, comp_name nvarchar(20));
create table supervises (spv_ss int, emp_ss int );
Here SUPRVISER_SS and EMP_SS are subset of SS. Now I have to find:
the name of all the companies who have more than 4 supervisors
I have made a query for the above problem but not sure whether it is correct or not
SELECT COMP_NAME , COUNT(EMP_SS) FROM WORKS
WHERE EMP_SS IN (SELECT DISTINCT SPV_SS FROM supervises)
GROUP BY COMP_NAME
HAVING COUNT(EMP_SS) > 4;
the name of supervisors who have the largest number of employees
but unable to get the required result of the above condition
SELECT SPV_SS, COUNT(*) max_ FROM supervises GROUP BY SPV_SS
You don't need to have a seperate table for supervisors unless they come with extra information that doesn't belong in the employee table, just add an extra field (foreign key) in Employee table that links to the primary key in the same table.
First question: select company just use a group by companyid clause and then check if the count of supervisors is larger than 4 for.
Second question: select count(empid) and supervisor, use group by supervisor clause and add order by clause on the count column
I explained the logic, as for the actual sql code, you're gonna have to figure that out yourself.
I need to make a really simple DB in an android application (I'm using SQLite) and have no idea how to make this query.
Let's say I have these two tables, linked together with the locationid from the first:
CREATE TABLE locations
(
locationid INTEGER PRIMARY KEY AUTO_INCREMENT,
floor INTEGER,
room INTEGER
);
CREATE TABLE entries
(
entryid INTEGER PRIMARY KEY AUTO_INCREMENT,
title TEXT,
summary TEXT,
date DATE,
FOREIGN KEY(location) REFERENCES locations(locationid)
);
How do I construct the following query: get all rows from table "entries" for room 308, floor 3?
SELECT *
FROM entries
WHERE locations = (SELECT locationid
FROM locations
WHERE room=308
AND floor=3)
Alternatively:
SELECT e.*
FROM entries e
JOIN locations l ON e.locations = l.locationid
WHERE l.room = 308
AND l.floor = 3
SELECT e.*
FROM locations l INNER JOIN entries e
ON l.locationid = e.location
WHERE l.floor = 3
AND l.room = 308
It's a simple JOIN statement :
select
locations.*, -- suppress this if only entries table are needed
entries.* -- you can select only date and title instead of everything
from locations
join entries
on entries.location=locations.locationid -- using your foreign key
where
locations.room=308 -- first condition
and locations.floor=3 -- second condition
;
You could use LEFT JOIN instead of JOIN if you want to retrieve informations on the room (for example) even if no data are linked within entries table.
Final word : I'm pretty sure the answer was already here on stackoverflow and on the web too.
I need to collect the values from the column "EmployeeID" of the table "Employees" and insert them into the column "EmployeeID" of the table "Incident".
At the end, the Values in the rows of the column "EmployeeID" should be arranged randomly.
More precisely;
I created 10 employees with their ID's, counting from 1 up to 10.
Those Employees, in fact the ID's, should receive random Incidents to work on.
So ... there are 10 ID's to spread on all Incidents - which might be 1000s.
How do i do this?
It's just for personal exercise on the local maschine.
I googled, but didn't find an explicit answer to my problem.
Should be simple to solve for you champs. :)
May anyone help me, please?
NOTES:
1) I've already created a column called "EmployeeID" in the table "Incident", therefore I'll need an update statement, won't I?
2) Schema:
[dbo].[EmployeeType]
[dbo].[Company]
[dbo].[Division]
[dbo].[Team]
[dbo].[sysdiagrams]
[dbo].[Incident]
[dbo].[Employees]
3) 1. Pre-solution:
CREATE TABLE IncidentToEmployee
(
IncidentToEmployeeID BIGINT IDENTITY(1,1) NOT NULL,
EmployeeID BIGINT NULL,
Incident FLOAT NULL
PRIMARY KEY CLUSTERED (IncidentToEmployeeID)
)
INSERT INTO IncidentToEmployee
SELECT
EmployeeID,
Incident
FROM dbo.Employees,
dbo.Incident
ORDER BY NEWID()
SELECT * FROM IncidentToEmployee
GO
3) 2. Output by INNER JOIN ON
In case you are wondering about the "Alias" column;
Nobody really knows which persons are behind the ID's - that's why I used an Alias column.
SELECT Employees.Alias,
IncidentToEmployee.Incident
FROM Employees
INNER JOIN
IncidentToEmployee ON
Employees.EmployeeID = IncidentToEmployee.EmployeeID
ORDER BY Alias
4) Final Solution
As I mentioned, I added at first a column called "EmployeeID" already to my "Incident" table. That's why I couldn't use an INSERT INTO statement at first and had to use an UPDATE statement. I found the most suitable solution now - without creating a new table as I did as a pre-solution.
Take a look at the following code:
ALTER Table Incident
ADD EmployeeID BIGINT NULL
UPDATE Incident
SET Incident.EmployeeID = EmployeeID
FROM Incident INNER JOIN Employees
ON Incident = EmployeeID
SELECT
EmployeeID,
Incident
FROM dbo.Employees,
dbo.Incident
ORDER BY NEWID()
Thank you all for your help - It took way longer to find a solution as I thought it would take; but I finally made it. Thanks!
UPDATE
I think you need to allocate different task to different user, a better approach will be to create a new table let's say EmployeeIncidents having columns Id(primary) , EmployeeID and IncidentID .
Now you can insert random EmployeesID and random IncidentID to new table, this way you will be able to keep records also ,
Updating Incident table will not be a smart choice.
INSERT INTO EmployeeIncidents
SELECT TOP ( 10 )
EmployeesID ,
IncidentID
FROM dbo.Employees,
dbo.Incident
ORDER BY NEWID()
Written by hand, so may need to tweak syntax, but something like this should do it. The Rand() function will give the same value unless seeded, so you can see with something like date to get randomness.
Insert Into Incidents
Select Top 10
EmployeeID
From Employees
Order By
Rand(GetDate())
I need some T-SQL help. We have an application which tracks Training Requirements assigned to each employee (such as CPR, First Aid, etc.). There are certain minimum Training Requirements which all employees must be assigned and my HR department wants me to give them the ability to assign those minimum Training Requirements to all personnel with the click of a button. So I have created a table called TrainingRequirementsForAllEmployees which has the TrainingRequirementID's of those identified minimum TrainingRequirements.
I want to insert rows into table Employee_X_TrainingRequirements for every employee in the Employees table joined with every row from TrainingRequirementsForAllEmployees.
I will add abbreviated table schema for clarity.
First table is Employees:
EmployeeNumber PK char(6)
EmployeeName varchar(50)
Second Table is TrainingRequirementsForAllEmployees:
TrainingRequirementID PK int
Third table (the one I need to Insert Into) is Employee_X_TrainingRequirements:
TrainingRequirementID PK int
EmployeeNumber PK char(6)
I don't know what the Stored Procedure should look like to achieve the results I need. Thanks for any help.
cross join operator is suitable when cartesian product of two sets of data is needed. So in the body of your stored procedure you should have something like:
insert into Employee_X_TrainingRequirements (TrainingRequirementID, EmployeeNumber)
select r.TrainingRequirementID, e.EmployeeNumber
from Employees e
cross join TrainingRequirementsForAllEmployees r
where not exists (
select 1 from Employee_X_TrainingRequirements
where TrainingRequirementID = r.TrainingRequirementID
and EmployeeNumber = e.EmployeeNumber
)