I am building a Hospital Management System and I wanted to make a table in the database that contains all the hospitals. Each hospital has another table that contains info about its employees.
If I wanted to add a new record (a new Hospital) in the hospital table after the system is released, can the system generate a new table for that new hospital's employees?
It would have a standard form and the system would ask the user to fill it (through GUI, or any other way).
Is it technically possible? And if not is there other ways to do it?
Why would you need to create a seperate table for each hospital? Add Hospital_ID as a column to the Employee table and then you can tell, from that one table, what hospital an mployee works for.
SQLFiddle
First you should read about Table relationships. It's really important that you understand how it works before desgnining your database.
Now as for your question, tables don't contain tables. This is why you should review you design.
You should have a those tables :
Hospital
---------------------------------------------------
| ID | Name | Address | Phone |
---------------------------------------------------
| 1 | SomeName | 13 Mercy Street | 555-555-5555 |
---------------------------------------------------
Employee
-------------------------
| ID | Hospital_ID | Name |
-------------------------
| 01 | 1 | John |
-------------------------
This way every employee is associated with an hospital. We now know John works in the SomeName hospital.
To help in your research,
Hospital.ID is a PRIMARY KEY
Employee.ID is a PRIMARY KEY
Employee.Hospital_ID is a FOREIGN KEY
Related
How can we auto generate column/fields in microsoft access table ?
Scenario......
I have a table with personal details of my employee (EmployDetails)
I wants to put their everyday attendance in an another table.
Rather using separate records for everyday, I want to use a single record for an employ..
Eg : I wants to create a table with fields like below
EmployID, 01Jan2020, 02Jan2020, 03Jan2020,.........25May2020 and so on.......
It means everyday I have to generate a column automatically...
Can anybody help me ?
Generally you would define columns manually (whether that is through a UI or SQL).
With the information given I think the proper solution is to have two tables.
You have your "EmployDetails" which you would put their general info (name, contact information etc), and the key which would be the employee ID (unique, can be autogenerated or manual, just needs to be unique)
You would have a second table with a foreign key to the empployee ID in "EmployDetails" with a column called Date, and another called details (or whatever you are trying to capture in your date column idea).
Then you simply add rows for each day. Then you do a join query between the tables to look up all the "days" for an employee. This is called normalisation and how relational databases (such as Access) are designed to be used.
Employee Table:
EmpID | NAME | CONTACT
----------------------
1 | Jim | 222-2222
2 | Jan | 555-5555
Detail table:
DetailID | EmpID (foreign key) | Date | Hours_worked | Notes
-------------------------------------------------------------
10231 | 1 | 01Jan2020| 5 | Lazy Jim took off early
10233 | 2 | 02Jan2020| 8 | Jan is a hard worker
10240 | 1 | 02Jan2020| 7.5 | Finally he stays a full day
To find what Jim worked you do a join:
SELECT Employee.EmpID, Employee.Name, Details.Date, Details.Hours_worked, Details.Notes
FROM Employee
JOIN Details ON Employee.EmpID=Details.EmpID;
Of course this will give you a normalised result (which is generally what's wanted so you can iterate over it):
EmpID | NAME | Date | Hours_worked | Notes
-----------------------------------------------
1 | Jim | 01Jan2020 | 5 | ......
1 | Jim | 02Jan2020 | 7 | .......
If you want the results denormalised you'll have to look into pivot tables.
See more on creating foreign keys
I have three tables with foreign key relationship with each other.
The table school will be uploaded manually. A student will login to the website and check their marks
The entire data is to be uploaded to another new database of different instance
The Login Id(stud_id) of the student in DB1 is 10 and Login Id(stud_id) of the student in DB2 is 1 in another instance.
For retaining the data of student_marks table, I intend to do the following steps,
1. Dump student_marks table from DB1
2. Copy it to DB2
NOTE: stud_id would be different for both the databases
Is there any way to do the above.
Refer the table below,
school:
id | name| place
-----+-------------
1 | sch1 | test
student:
id | school_id| stud_name
-----+-------------
1 | 1 | stud1
student_marks:
id | stud_id| subj1 | subj2
-----+-----------------------
1 | 1 | 30 | 30
Thanks in advance!
First Disable the foreign key constraint, then dump the data and after that again enable the foreign key constraint or you can put foreign key constraint after migrating the data.
Consider the following postgres (version 9.4) database:
testbase=# select * from employee;
id | name
----+----------------------------------
1 | johnson, jack
2 | jackson, john
(2 rows)
testbase=# select * from worklog;
id | activity | employee | time
----+----------------------------------+----------+----------------------------
1 | department alpha | 1 | 2018-01-27 20:32:16.512677
2 | department beta | 1 | 2018-01-27 20:32:18.112356
5 | break | 1 | 2018-01-27 20:32:22.255563
3 | department gamma | 2 | 2018-01-27 20:32:20.073173
4 | department gamma | 2 | 2018-01-27 20:32:21.05962
(5 rows)
The column 'name' in table 'employee' is of type character(32) and unique, the column 'employee' in 'worklog' references 'id' from the table 'employee'. The column 'id' is the primary key in either table.
I can see all activities from a certain employee by issuing:
testbase=# select * from worklog where employee=(select id from employee where name='johnson, jack');
id | activity | employee | time
----+----------------------------------+----------+----------------------------
1 | department alpha | 1 | 2018-01-27 20:32:16.512677
2 | department beta | 1 | 2018-01-27 20:32:18.112356
5 | break | 1 | 2018-01-27 20:32:22.255563
(3 rows)
I would rather like to simplify the query to
testbase=# select * from worklog where employee='johnson, jack';
For this I would change 'employee' to type character(32) in 'worklog' and declare 'name' as primary key in table 'employee'. Column 'employee' in 'worklog' would, of course, reference 'name' from table 'employee'.
My question:
Will every new row in 'worklog' require additional 32 bytes for name of the 'employee' or will postgres internally just keep a pointer to the foreign field without duplicating the name for every new row?
I suppose that the answer for my question is somewhere in the documentation but I could not find it. It would be very helpful if someone could provide an according link.
PS: I did find this thread, however, there was no link to some official documentation. The behaviour might also have changed, since the thread is now over seven years old.
Postgres will store the data that you tell it to store. There are some new databases that will do compression under the hood -- and Postgres might have features to enable that (I do not know all Postgres features).
But, you shouldn't do this. Integer primary keys are more efficient than strings for three reasons:
They are fixed length in bytes.
They are shorter.
Collations are not an issue.
Stick with your original query, but write it using a join:
select wl.*
from worklog wl join
employee e
on wl.employee = e.id
where e.name = 'johnson, jack';
I suggest this because this is more consistent with how SQL works and makes it easier to choose multiple employees.
If you want to see the name and not the id, create a view (say v_worklog) and add in the employee name.
I'm trying to build a database with multiple tables for a study/research. This is the first time I'm designing database of this magnitude; the database grows by 100-200 records a day, and so far I have the data since 2010. Out of all the data, Generic Sequence Number, Product Name and the Strength of a drug (prescription) is slightly bothering me. This is what I have done so far:
Generic Seq number is unique to the strength of drug (product name). So, I have a table that contains id, generic seq no, and strength. Another table is for prod_id and product name. Each Generic seq number may have one or more product name, and each product name may have different generic seq number based on the strength. So, I set it up as many-to-many relationship. I created another table for this relationship that contains rx_id, drug_id, and prod_id. Since many patients may be prescribed for the same drug, the drug_id and prod_id may repeat several times in the rx_table.
My first question is, is this design appropriate?
How should I insert the data into rx_table? Should I create new record every time for new data even if the drug_id and prod_id already exist in the rx_table, or should I look for the rx_id where the drug_id and prod_id sequence exist and insert the rx_id into the other main table (not shown) which contains other data.
Or is this question too vague?
Thank you for your help.
I don't know what exactly is your Generic Sequence Number so i'll just use a real life drug example. From your description i think it's pretty similar to your application. Lets say you have Paracetamol as an agent. Then your Generic Sequence Number table would be something like
drug_id | generic_seq_no | strength
--------+--------------------+----------
1 | Paracetamol-100 | 100
2 | Paracetamol-250 | 250
3 | Paracetamol-500 | 500
Your product table would contain the names of the trademarks:
prod_id | prod_name
----------+------------
1 | Tylenol
2 | Captin
3 | Panadol
the rx_table contains the combinations of trademark name, agent and strength:
rx_id | drug_id | prod_id
-------+----------+----------
1 | 1 | 1
2 | 1 | 2
3 | 1 | 3
4 | 2 | 1
5 | 2 | 2
6 | 3 | 2
7 | 3 | 3
So e.g. the first row would be Tylenol, containing 100 mg of Paracetamol. Now you have what can be prescribed by a doctor and that's what you already did so far. So as i said your approach is fine.
Now you need (or have?) another table with all your patients
patient_id | firstname | lastname
-----------+-----------+-----------
1 | John | Doe
2 | Jane | Doe
In the end, you must link your trademark/agent/strength combination to the patients. Since one patient may get different drugs and multiple patients may get the same drug you need another many-to-many-relation, let's call it prescription
prescription_id | patient_id | rx_id
----------------+------------+------
1 | 1 | 1
2 | 1 | 3
3 | 2 | 4
This means John Doe will get Tylenol and Panadol containing 100 mg Paracetamol each. Jane Doe will receive Tylenol with 250 mg Paracetamol. I think the table you will be inserting the most is the prescription table in this model.
I am trying to wrap my head around the correct way of connecting Employees to Projects but for some reason i am having a hard time with this. I have the following so far:
-------------------
| Employee |
-------------------
| EmployeeID | PK |
-------------------
| Name | |
-------------------
| Position | |
-------------------
--------------------
| Project |
--------------------
| ProjectID | PK |
--------------------
| Name | |
--------------------
| Description | |
--------------------
I am going to have many Employees and many Projects and each employee can be a part of many projects while each project would have many employees attached to it. I am having an issue with how to make the connection between the two. Can someone please help talk me through this? Thanks!
You need a joining table to create two one-to-many relationships:
employee
employee_id PK
Relates to:
employee_project
employee_id PK
project_id PK
With project also related to the above:
project
project_id PK
So your employees can be related to your employee_project table but your projects can be related to your employee_project table too.
Having two primary keys on a table is called a Composite Primary Key (two foreign keys in this case).
Create a Many-2-Many relationships Table like so.
--------------------------
| EmployeeProject |
--------------------------
| EmployeeID | PK |
-------------------
| ProjectID | PK |
--------------------------
Your PK on this table with be Combination of EmployeeID + ProjectID (called Composite Primary Key).
To get Employees that have Projects, your SQL will look like so.
SELECT emp.*
FROM Employee emp
INNER JOIN Project prj ON emp.EmployeeID = prj.EmployeeID
If you want to get Employees who *do not have any project*s assigned, your SQL will look like so.
SELECT emp.*
FROM Employee emp
LEFT JOIN Project prj ON emp.EmployeeID = prj.EmployeeID
WHERE prj,EmployeeID IS NULL
You need an intermediate table where you will store EmployeeID and ProjectID as foreign keys, thus making the connection between two. (M : N relation)
Create a third table and store EmployeeID and ProjectID in that table, so now you can query anything you want.
To do that you need a third table which contains EmployeeID and ProjectID. Mark both IDs as primary key. You have to do a double join if you want to select them though but it's the best way to handle it.