I've an issue with a n-n relationship while trying to insert in the "middle table".
The goal is to associate Commune and ZipCode (in France, a Commune is a city, and the city name can have multiple ZipCode because there are commune with the same name. But not in the same place)
And a ZipCode can handle multiple City, here is my n-n relationShip.
So here is the request i use :
INSERT INTO FR(IDCODEPOSTAL, IDCOM_SIM)
VALUES
('24209 CEDEX', (SELECT DISTINCT IDCOM_SIM FROM COMMUNE WHERE NCCENR='Creysse'));
But here the SELECT returns 2 rows. I've read much but I didn't find a way to deal with this.
I'm not sure what you are trying to achieve, but usually you'd use an INSERT ... SELECT (without the VALUES) to insert multiple rows with a single statement:
INSERT INTO FR
(IDCODEPOSTAL, IDCOM_SIM)
VALUES
SELECT '24209 CEDEX', IDCOM_SIM
FROM COMMUNE
WHERE NCCENR='Creysse';
If you however want to insert only a single row, you need to make sure the sub-select returns only one. This is usually done using an aggregate function such as max()
INSERT INTO FR
(
IDCODEPOSTAL,
IDCOM_SIM
)
VALUES
(
'24209 CEDEX',
(SELECT max(IDCOM_SIM) FROM COMMUNE WHERE NCCENR='Creysse')
);
Related
I have a table that has 3 columns ID(Primary Key), Name, City.
I need to import data from another table that has only Name and City.
I can write insert into table 1(Name, City) select Name, City from table2.
But then I need ID in table 1 which needs to be inserted using a sequence.
I tried this:
insert into table1(ID, Name,City) values(seq.nextval, select distinct name, city from table2). But I am receiving an error saying an insufficient number of values.
I am trying it in SQL Oracle. Can someone please help me with this?
You are mixing the insert ... values and insert ... select syntax.
You edited your question to include distinct, implying you have duplicate name/city pairs that you want to suppress; but neither version gets the error you reported. If you don't have duplicates then you can just do:
insert into table1(ID, Name,City)
select seq.nextval, name, city from table2;
If you do have duplicates then you can't just add the distinct keyword, but you can use a subquery:
insert into table1 (id, name, city)
select seq.nextval, name, city
from (
select distinct name, city
from table2
);
db<>fiddle
You could also set the ID via a trigger. If you we're on a recent version you could use an identity column instead - but you tagged the question with Oracle 11g, where those are not available.
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've got a table that has a text column and some other identifying features. I want to be able to group by one of the features and find out whether the text in the groups are similar or not. I want to use this to determine if there are multiple groups in my data or a single group (with some possible bad spelling) so that I can provide a rough "confidence" value showing if the aggregate represents a single group or not.
CREATE TABLE data_test (
Id serial primary key,
Name VARCHAR(70) NOT NULL,
Job VARCHAR(100) NOT NULL);
INSERT INTO data_test
(Name, Job)
VALUES
('John', 'Astronaut'),
('John', 'Astronaut'),
('Ann', 'Sales'),
('Jon', 'Astronaut'),
('Jason', 'Sales'),
('Pranav', 'Sales'),
('Todd', 'Sales'),
('John', 'Astronaut');
I'd like to run a query that was something like:
select
Job,
count(Name),
Similarity_Agg(Name)
from data_test
group by Job;
and receive
Job count Similarity
Sales 4 0.1
Astronaut 4 0.9
Basically showing that Astronaut names are very similar (or, more likely in my data, all the rows are referring to a single astronaut) and the Sales names aren't (more people working in sales than in space). I see there is a Postgres Module that can handle comparing two strings but it doesn't seem to have any aggregate functions in it.
Any ideas?
One option is a self-join:
select
d.job,
count(distinct d.id) cnt,
avg(similarly(d.name, d1.name)) avg_similarity
from data_test d
inner join data_test d1 on d1.job = d.job
group by d.job
I have a simple task to do, sadly I am stuck. I have two tables: Countries and Continents.
Countries has these columns:
CountryID, CountryName, ContinentID.
Continents has these columns :
ContinentID, ContinentName.
Now, I need to insert particular ContinentId into Countries.ContinentID i.e 1. Belgium 1.
I would like to write a INSERT INTO query, that will allow me to insert one value of ContinentID to multiple rows of CountryID. Is there a way to do that?
I think you need update statement:
update Countries set ContinentID = 1
--values (1,2,3,4,5,6) are just for example
where CountryID in (1,2,3,4,5,6)
I am not sure if I understand your question correctly
you can use SELECT in your insert statement
example:
INSERT INTO Countries (CountryID)
SELECT ContinentID FROM Continents GROUP BY ContinentName
I'm trying to normalize a mysql database....
I currently have a table that contains 11 columns for "categories". The first column is a user_id and the other 10 are category_id_1 - category_id_10. Some rows may only contain a category_id up to category_id_1 and the rest might be NULL.
I then have a table that has 2 columns, user_id and category_id...
What is the best way to transfer all of the data into separate rows in table 2 without adding a row for columns that are NULL in table 1?
thanks!
You can create a single query to do all the work, it just takes a bit of copy and pasting, and adjusting the column name:
INSERT INTO table2
SELECT * FROM (
SELECT user_id, category_id_1 AS category_id FROM table1
UNION ALL
SELECT user_id, category_id_2 FROM table1
UNION ALL
SELECT user_id, category_id_3 FROM table1
) AS T
WHERE category_id IS NOT NULL;
Since you only have to do this 10 times, and you can throw the code away when you are finished, I would think that this is the easiest way.
One table for users:
users(id, name, username, etc)
One for categories:
categories(id, category_name)
One to link the two, including any extra information you might want on that join.
categories_users(user_id, category_id)
-- or with extra information --
categories_users(user_id, category_id, date_created, notes)
To transfer the data across to the link table would be a case of writing a series of SQL INSERT statements. There's probably some awesome way to do it in one go, but since there's only 11 categories, just copy-and-paste IMO:
INSERT INTO categories_users
SELECT user_id, 1
FROM old_categories
WHERE category_1 IS NOT NULL