I'm trying to implement a very basic banking system.
the goal is to have different types of transactions ( deposit, withdraw, transfer ) inside a table and refer to them as IDs inside transaction tables.
CREATE TABLE transaction_types (
id INTEGER AUTO_INCREMENT PRIMARY KEY,
name VARCHAR UNIQUE NOT NULL
)
CREATE TABLE transactions (
id INTEGER AUTO_INCREMENT PRIMARY KEY,
type_id INTEGER NOT NULL,
amount FLOAT NOT NULL
)
What I'm trying to accomplish is:
When inserting into transactions table no record can have an invalid type_id ( type_id should exist in transaction_types table )
First of all get type_id from transaction_types table and then insert inside transactions table, with one query ( if it's possible, I'm fairly new )
I'm using Node.js/Typescript and PostgreSQL, any help is appreciated a lot.
For (1): modify Transactions table definition by adding REFERENCES transaction_types(id) to the end of the type_id column definition prior to the comma.
For (2), assuming you know the name of the transaction_type, you can accomplish this by:
INSERT INTO transactions(type_id, amount)
VALUES ((SELECT id from transaction_types WHERE name = 'Withdrawal'), 999.99)
By the way, my PostgreSQL requires SERIAL instead of INTEGER AUTOINCREMENT
Related
I'm trying to insert values from two tables into a new table, but I keep getting the 'column count does not match' when it does. This is what I have so far:
create table contribution (
contb_id integer primary key auto_increment,
cand_id varchar(12),
contbr_id varchar(12),
amount numeric(8,2),
date varchar(20),
election_type varchar(20),
tran_id varchar(20),
foreign key (cand_id) references candidate,
foreign key (contbr_id) references contributor
);
and to insert the values into it:
INSERT INTO contribution (cand_id, contbr_id, amount, date, election_type, tran_id)
SELECT (cand_id, cb.contbr_id, contb_receipt_amt, contb_receipt_dt, election_tp, tran_id)
FROM campaign, contributor cb
Any help would be greatly appreciated!
Essentially the answer is here: https://stackoverflow.com/a/5391390/12672179
For your case when you are inserting using select you should NOT have the brackets. Brackets in a select statement act very funky and essentially is making each column combine into 1 in its view. So to fix the column count issue in your INSERT statement just do this
INSERT INTO contribution (cand_id, contbr_id, amount, date, election_type, tran_id)
SELECT cand_id, cb.contbr_id, contb_receipt_amt, contb_receipt_dt, election_tp, tran_id
FROM campaign, contributor cb
Additionally this is still wrong as you cannot do two from tables in the same FROM instead you should JOIN the second table ON a value where the two tables match (In other words the foreign key field). I'm not going to tell you which type of JOIN to use as that depends on your data and if every single value has a link or not.
Finally you should also include a WHERE so sql knows which values to fetch if you only want to do specific and not all.
I'm trying to implement an Oracle SQL database, in one of my tables I must introduce a restriction which does not allow to have more than 4 people in the same group:
I've tried this:
CREATE TABLE PERSON (name VARCHAR (20) PRIMARY KEY, group VARCHAR (3), CHECK (COUNT (*) group FROM PERSON) <=4);
also this (among others):
CREATE TABLE PERSON (name VARCHAR (20) PRIMARY KEY, group VARCHAR (3), CHECK NOT EXISTS (Select COUNT(*) FROM PERSON GROUP BY group HAVING COUNT(*) > 4);
But I'm getting errors every time (ORA-00934: group function is not allowed here or ORA-02251: subquery not allowed here.
What is the correct way to do it?
You have multiple issues with this
CREATE TABLE PERSON (
name VARCHAR(20) PRIMARY KEY,
group VARCHAR(3),
CHECK (COUNT (*) group FROM PERSON) <=4);
);
Oracle explicitly prefers VARCHAR2() to VARCHAR().
GROUP is a really bad name for a column, because it is a keyword. Surely you can find something like group_name or whatever for the name.
CHECK constraints only work within a single row.
Probably the best way to handle this is:
Create a new table called groups -- or whatever. It should have a group_id as well as group_name and num_persons.
Add triggers to person to keep the counter up-to-date for inserts, deletes, and updates to person.
Add a check constraint to groups, say check (num_persons <= 4).
You need to create the table as following:
CREATE TABLE PERSON (
name VARCHAR2(20) PRIMARY KEY,
group_ VARCHAR2(3) -- added _ after column name
); -- used varchar2 as data type of column
Then create before insert trigger as following:
create trigger person_trg
before insert on person
for each row
declare
group_cnt number;
begin
select count(distinct name)
into group_cnt
from person
where group_ = :new.group_;
if group_cnt = 4 then
raise_application_error(-20001, 'more than 4 persons are not allowed in the group');
end if;
end;
/
I have used distinct person name as more than 4 distinct persons are not allowed in the group as per your requirement.
db<>fiddle demo
Cheers!!
I'm working on a database for my school project in which I have to produce a functional database by normalizing sample tables given to us.
One table I'm having trouble with is itineraries. I produce 3 tables from the normalization which are "Destinations", "Itineraries" and "Itinerary_Destinations".
The code for Destinations is:
create table Destinations
(
DestinationID varchar(5) primary key,
Name varchar(45)
);
The code for Itineraries is:
create table Itineraries
(
ItineraryID varchar(5),
Name varchar(45)
);
The code for the last table is:
create table Itinerary_Destinations
(
DI varchar(5) primary key,
ItineraryID varchar(5) foreign key references Itineraries(ItineraryID),
Itinerary_Name varchar(45),
DestinationID varchar(5) foreign key references Destinations(DestinationID),
Destination_Name varchar(45)
);
Data has already been inserted into all 3 tables with the exception of 'Destination_Name' and 'Itinerary_Name' columns. The code I'm attempting to use is returning as error. The code is shown below.
insert into Itinerary_Destinations (Itinerary_name)
select Name from Itineraries where
Itineraries.ItineraryID = ItineraryID;
The error it returns is
Msg 515, Level 16, State 2, Line 1 Cannot insert the value NULL into
column 'DI', table 'DDDAssignment.dbo.Itinerary_Destinations'; column
does not allow nulls. INSERT fails. The statement has been terminated.
Is there a method to accomplish the task of inserting the Destination_Name and Itinerary_Name without creating new records that require primary keys?
Or should I do it manually?
If you want to modify records which already exist, then you should be using an UPDATE rather than an INSERT:
UPDATE a
SET Itinerary_name = b.Name
FROM Itinerary_Destinations a
INNER JOIN Itinerary_name b
ON a.ItineraryID = b.ItineraryID;
But, if you do have some data which is not already logically associated with the Itinerary_Destinations table, then using an insert is appropriate.
use coalesce funtion in case null it will insert blank string, as your column does not allow null value thats why you got that error in your query
insert into Itinerary_Destinations (Itinerary_name)
select coalesce(Name,' ') from Itineraries where
Itineraries.ItineraryID = ItineraryID;
In SQL Server I have a table as RawTable (temp) which gets fed by a CVS, let's say it has 22 columns in it. Then, I need to copy existing records (ONLY FEW COLUMNs NOT ALL) into another table as Visitors which is not temporary table.
Visitor table has an ID column as INT and that is primary key and incremental.
RawData table
id PK, int not null
VisitorDate Varchar(10)
VisitorTime Varchar(11)
Visitors table
VisitorID, PK, big int, not null
VisitorDate, Varchar(10), null
VisitorTime Varchar(11), null
So I did:
insert into [dbo].[Visitors] ( [VisitorDate], [VisitorTime])
select [VisitorDate], [VisitorTime]
from RawTable /*this is temp table */
Seems SQL Server doesn't like this method so it throws
Msg 515, Level 16, State 2, Line 1
Cannot insert the value NULL into column 'VisitorID', table 'TS.dbo.Visitors'; column does not allow nulls. INSERT fails. The statement has been terminated.
How can I keep Sql Server not to complain about the primary key? this column as you know better will be fed by sql server itself.
Any idea?
Just because your visitors table has an ID column that is the primary key doesn't mean that the server will supply your ID values for you. if you want SQL to provide the ID's then you need to alter the table definition and make the visitorsId column an IDENTITY column.
Otherwise, you can psuedo-create these id's during the insert with the ROW_NUMBER function -
DECLARE #maxId INT;
SELECT #maxId = (SELECT MAX(visitorsId) FROM dbo.visitors);
INSERT INTO [dbo].[Visitors] ( [visitorsId],[VisitorDate], [VisitorTime])
SELECT #maxId + ROW_NUMBER() OVER (ORDER BY visitorDate), [VisitorDate], [VisitorTime]
from RawTable /*this is temp table */
I have only done databases without relations, but now I need to do something more serious and correct.
Here is my database design:
Kunde = Customer
Vare = Product
Ordre = Order (Read: I want to make an order)
VareGruppe = ehm..type? (Read: Car, chair, closet etc.)
VareOrdre = Product_Orders
Here is my SQL (SQLite) schema:
CREATE TABLE Post (
Postnr INTEGER NOT NULL PRIMARY KEY,
Bynavn VARCHAR(50) NOT NULL
);
CREATE TABLE Kunde (
CPR INTEGER NOT NULL PRIMARY KEY,
Navn VARCHAR(50) NOT NULL,
Tlf INTEGER NOT NULL,
Adresse VARCHAR(50) NOT NULL,
Postnr INTEGER NOT NULL
CONSTRAINT fk_postnr_post REFERENCES Post(Postnr)
);
CREATE TABLE Varegruppe (
VGnr INTEGER PRIMARY KEY,
Typenavn VARCHAR(50) NOT NULL
);
CREATE TABLE Vare (
Vnr INTEGER PRIMARY KEY,
Navn VARCHAR(50) NOT NULL,
Pris DEC NOT NULL,
Beholdning INTEGER NOT NULL,
VGnr INTEGER NOT NULL
CONSTRAINT fk_varegruppevgnr_vgnr REFERENCES Varegruppe(VGnr)
);
CREATE TABLE Ordre (
Onr INTEGER PRIMARY KEY,
CPR INTEGER NOT NULL
CONSTRAINT fk_kundecpr_cpr REFERENCES Kunde(CPR),
Dato DATETIME NOT NULL,
SamletPris DEC NOT NULL
);
CREATE TABLE VareOrdre (
VareOrdreID INTEGER PRIMARY KEY,
Onr INTEGER NOT NULL
CONSTRAINT fk_ordrenr_onr REFERENCES Ordre(Onr),
Vnr INTEGER NOT NULL
CONSTRAINT fk_varevnr_vnr REFERENCES Vare(Vnr),
Antal INTEGER NOT NULL
);
It should work correctly.
But I am confused about Product_Orders.
How do I create an order? For example, 2 products using SQL INSERT INTO?
I can get nothing to work.
So far:
Only when I manually insert products and data into Product_Orders and then add that data to Orders = which makes it complete. Or the other way around (create an order in with 1 SQL, then manually inserting products into Product_orders - 1 SQL for each entry)
You should first create an order and then insert products in the table Product_Orders. This is necessary because you need an actual order with an id to associate it with the table Product_Orders.
You always should create a record in the foreign-key table before being able to create one in your current table. That way you should create a "Post", customer, type, product, order and product_order.
Try this ...
first you have to insert a customer
insert into kunde values(1, 'navn', 1, 'adresse', 1)
then you insert a type
insert into VareGruppe values(1, 'Type1')
then you insert a product
insert into vare values(1, 'product1', '10.0', 1, 1)
then you add an order
insert into ordre values(1, 1, '20090101', '10.0')
then you insert a register to the product_orders table
insert into VareOrdre values (1, 1, 1, 1)
I think this is it. :-)
As the primary keys are autoincrement, don't add them to the insert and specify the columns like this
insert into vare(Nav, Pris, Beholdning, VGnr) values('product1', '10.0', 1, 1)
Use Select ##identity to see the onr value
I think you already have the hang of what needs to happen. But what I think you are getting at is how to ensure data integrity.
This is where Transactions become important.
http://www.sqlteam.com/article/introduction-to-transactions
Is it the SalesPrice (I'm guessing that's what SamletPris means) that's causing the issue? I can see that being a problem here. One common design solution is to have 2 tables: Order and OrderLine. The Order is a header table - it will have the foreign key relationship to the Customer table, and any other 'top level' data. The OrderLine table has FK relationships to the Order table and to the Product table, along with quantity, unit price, etc. that are unique to an order's line item. Now, to get the sales price for an order, you sum the (unit price * quantity) of the OrderLine table for that order. Storing the SalesPrice for a whole order is likely to cause big issues down the line.
A note just in case this is MySQL: If you're using MyISAM, the MySQL server ignores the foreign keys completely. You have to set the engine to InnoDB if you want any kind of integrity actually enforced on the database end instead of just in your logic. This isn't your question but it is something to be aware of.
fbinder got the question right :)