I am making a database with postgresql 9.1
Given tables:
CREATE TABLE rooms(
room_number int,
property_id int,
type character varying,
PRIMARY KEY (room_number, property_id)
);
Insert into rooms values (1,1,double),(2,1,double),(3,1,triple)
CREATE TABLE reservations(
reservation_ID int,
property_id int,
arrival date,
departure date,
room_num int,
PRIMARY KEY(reservation_ID,property_id)
FOREIGN KEY (room_number, property_id)
);
INSERT INTO orders VALUES (1,1,2013-9-27,2013-9-30,1),
(2,1,2013-9-27,2013-9-28,2),
(3,1,2013-9-29,2013-9-30,3);
I want to give 2 dates and check availability in between. So at the 1st column should apear:
all the dates between the given and
additional one column for every type of the room displaying the availability.
So my result, given 2013-9-27 & 2013-9-30 as input, must be sth like this:
I think the best solution would be use both generate_series() and crosstab() to create a dynamic table. Moreover you can use a left join from a CTE to your data tables so you get better information. Something like:
WITH daterange as (
SELECT s::date as day FROM generate_series(?, ?, '1 day')
)
SELECT dr.day, sum(case when r.type = 'double' then r.qty else 0) as room_double,
sum(case when r.type = 'triple' then r.qty else 0) as room_triple....
);
But note that crosstab would make the second query a little easier.
Related
I have a table where records have a (begin, end) time window of existence (for things like employement duration, birth and death, rent duration, ...)
begin IS NULL or end IS NULL if there is no bound.
CREATE TABLE mytable(
id int primary key,
value int, --UNIQUE at any point in time
begin datetime NULL,
end datetime NULL
);
I want column value to be unique at any point in time.
INSERT INTO mytable VALUES(1, 1, '2021-07-23', '2021-07-24'),(2, 1, '2021-07-25', NULL);
Is OK
Whereas
INSERT INTO mytable VALUES(1, 1, '2021-07-23', '2021-07-30'),(2, 1, '2021-07-25', NULL);
Is not OK, because both records have value=1 and overlapping time windows.
Is there a way to enforce such a constraint in SQL ?
You can't do this on the table, no, as there's nothing to make UNIQUE on.
What you could do, however, is use a VIEW to enforce it.
Firstly, let's create your table. I assume the columns datetime, should actually be begin and end; I recommend against these names as they are reserved keywords. As such I am calling them DateBegin and DateEnd. I am also assuming that they are date only (no time portion) values and so define them as a date not a datetime:
CREATE TABLE dbo.mytable(ID int primary key,
Value int,
[BeginDate] date NULL,
[EndEnd] date NULL);
And we'll INSERT your first 2 rows, as they are "ok":
INSERT INTO dbo.mytable (ID, Value, BeginDate, EndDate)
VALUES(1, 1, '20210723', '20210724'),
(2, 1, '20210725', NULL);
Now we need to make a VIEW, but we need one row per date. As such you'll want to create a Calendar Table. I'm not going to cover how to create one here, but there are literally 100's of articles, such as there on SQL Server Central: Bones of SQL - The Calendar Table, Calendar Tables in T-SQL.
Once you have your Calendar table, you can create the VIEW below, which JOINs the data in your table to the calendar table. We're going to make it so that the VIEW just returns the columns value and the date. WE're also going to schemabind it; this means we'll be able to add an UNIQUE INDEX to it:
CREATE VIEW dbo.MyView
WITH SCHEMABINDING
AS
SELECT MT.[Value],
CT.CalendarDate
FROM dbo.MyTable MT
JOIN dbo.CalendarTable CT ON MT.BeginDate <= CT.CalendarDate --I assume, despite your schema, MT.BeginDate can't be NULL
AND (MT.EndDate >= CT.CalendarDate OR MT.EndDate IS NULL);
Now we have a VIEW that has a row for each date, and for each value. This means we can now create our UNIQUE INDEX:
CREATE UNIQUE CLUSTERED INDEX MyIndex ON dbo.MyView ([Value], CalendarDate);
Now if we try to INSERT a row that is on the same date and value, we'll get an error:
INSERT INTO dbo.MyTable (ID, Value, BeginDate, EndDate)
VALUES(3, 1, '20210720', '20210723');
Cannot insert duplicate key row in object 'dbo.MyView' with unique index 'MyIndex'. The duplicate key value is (1, 2021-07-23).
I want to add the results of a query into a table. There are multiple values, being inserted into multiple rows that are currently NULLS.
I have the following tables:
CREATE TABLE CAR (
CarID INT NOT NULL PRIMARY KEY,
Make VARCHAR (30) NOT NULL,
Model VARCHAR (30) NOT NULL,
Type VARCHAR (30) NOT NULL,
YearModel INT NOT NULL,
Price VARCHAR (100) NOT NULL,
);
CREATE TABLE [TRANSACTION] (
tID INT NOT NULL PRIMARY KEY,
cID INT NOT NULL FOREIGN KEY REFERENCES CUSTOMER(CID),
CarID INT NOT NULL FOREIGN KEY REFERENCES CAR(CARID),
eID INT NOT NULL FOREIGN KEY REFERENCES EMPLOYEE(EID),
tDate DATE,
PickupDate DATE NOT NULL,
ReturnDate DATE NOT NULL
);
I then had to add a new column:
ALTER TABLE [TRANSACTION]
ADD Amount_Due int;
The following code gives me the results I need:
SELECT Price*DATEDIFF(DAY,PickupDate, ReturnDate)
FROM [TRANSACTION], CAR
WHERE [TRANSACTION].CarID = CAR.CarID
But I don't know how to insert all of the data into my Amount_Due column.
I have tried to use INSERT INTO, but it's telling me I have a syntax error near Amount_Due.
INSERT INTO [TRANSACTION] Amount_Due
SELECT Price*DATEDIFF(DAY,PickupDate, ReturnDate)
FROM CAR, [TRANSACTION]
WHERE CAR.CarID = [TRANSACTION].CarID
I have played around with INSERT INTO and UPDATE and I cannot wrap my head around what I'm doing wrong, or what I am missing.
I'm using SQL SMS 2018
Thank you for any help.
You are not inserting data you are updating existing rows, so you need to update:
update t set
t.Amount_Due = c.Price * DateDiff(day, c.PickupDate, c.ReturnDate)
from [transaction] t
join car c on c.carId=t.carId
Notes
Always use proper join syntax, avoid adding tables separated by
commas.
Also always alias your tables with meaningful short
aliases for readability.
Avoid using reserved words for objects eg
transaction - if your table contains more than 1 row then call it
transactions and avoid the need to always have to use [] to avoid
ambiguity.
SSMS is not SQL Server, SSMS is just an application used to access SQL Server. Use select ##version if you ever need to know your SQL Server version.
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 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
how to create date format yyyy-mm with postgresql11
CREATE TABLE public."ASSOL"
(
id integer NOT NULL,
"ind" character(50) ,
"s_R" character(50) ,
"R" character(50) ,
"th" character(50),
"C_O" character(50) ,
"ASSOL" numeric(11,3),
date date,
CONSTRAINT "ASSOL_pkey" PRIMARY KEY (id)
This is a variation of Kaushik's answer.
You should just use the date data type. There is no need to create another type for this. However, I would implement this use a check constraint:
CREATE TABLE public.ASSOL (
id serial primary key,
ind varchar(50) ,
s_R varchar(50) ,
R varchar(50) ,
th varchar(50),
C_O varchar(50) ,
ASSOL numeric(11,3),
yyyymm date,
constraint chk_assol_date check (date = date_trunc('month', date))
);
This only allows you to insert values that are the first day of the month. Other inserts will fail.
Additional notes:
Don't use double quotes when creating tables. You then have to refer to the columns/tables using double quotes, which just clutters queries. Your identifiers should be case-insensitive.
An integer primary key would normally be a serial column.
NOT NULL is redundant for a PRIMARY KEY column.
Use reasonable names for columns. If you want a column to represent a month, then yyyymm is more informative than date.
Postgres stores varchar() and char() in the same way, but for most databases, varchar() is preferred because trailing spaces actually occupy bytes on the data pages.
for year and month you can try like below
SELECT to_char(now(),'YYYY-MM') as year_month
year_month
2019-05
You cannot create a date datatype that stores only the year and month component. There's no such option available at the data type level.
If you want to to truncate the day component to default it to start of month, you may do it. This is as good as having only the month and year component as all the dates will have day = 1 and only the month and year would change as per the time of running insert.
For Eg:
create table t ( id int, col1 text,
"date" date default date_trunc('month',current_date) );
insert into t(id,col1) values ( 1, 'TEXT1');
select * from t
d col1 date
1 TEXT1 2019-05-01
If you do not want to store a default date, simply use the date_trunc('month,date) expression wherever needed, it could either be in group by or in a select query.