I'm trying to split data from Username column in a table like this:
Table1
ID Username
1 UserA,UserB,UserC
and I want to insert it to another table. the result will be like this:
Table2
ID Username
1 UserA
1 UserB
1 UserC
is this possible to do this in postgresql?
thanks in advance
You can split the value and then unnest it:
insert into table2 (id, username)
select t1.id, ut.username
from table1 t1
cross join unnest(string_to_array(t1.username), ',')) as ut(username)
Related
I have done similar task where I can insert a row into a table if data doesn't exists:
WITH
user_exists AS (
Select id from users where username='%s'
),
user_new AS (
INSERT INTO users (username)
SELECT w.username FROM (values ('%s')) w(username)
WHERE not exists
(SELECT 1 FROM users u WHERE u.username = w.username)
returning id
)
INSERT INTO feedbacks ('static_row', userid)
SELECT
'static_data',
(SELECT id FROM users_exists UNION ALL SELECT id FROM users_new) AS userid
Above works well when we insert a new row to feedbacks table. If user doesn't exists it inserts data in users table and returns id which is used for inserting data to feedbacks table.
But now my use case is, I have to insert multiple rows into the feedback table. Something like this:
user_variable = ['a','b', ...]
Insert into feedbacks ('static_row', userid)
VALUES
('sample_data', (Select if from users where username='a')),
('sample_data', (Select if from users where username='b')),
('sample_data', (Select if from users where username='c'))
For above case, how we can insert a new row to users table if username='b' doesn't exists.
Something like this might work for you:
Insert into feedbacks (username)
select distinct uname from
(values
('sample_data'),
('sample_data2'),
('sample_data3')
) s(uname)
where not exists(select 1 from feedbacks where username=uname);
I have two tables in postgresql
One table is of the form
Create table table1(
ID serial PRIMARY KEY,
Type []Text
)
Create table table2(
type text,
sellerID int
)
Now i want to get all the rows from table1 which are having type same that in table2 but the problem is that in table1 the type is an array.
In case the type in the table has an identifiable delimiter like ',' ,';' etc. you can rewrite the query as regexp_split_to_table(type,',') or versions later than 9.5 unnest function can be use too.
For eg.,
select * from
( select id ,regexp_split_to_table(type,',') from table1)table1
inner join
select * from table2
on trim(table1.type) = trim(table2.type)
Another good example can be found - https://www.dbrnd.com/2017/03/postgresql-regexp_split_to_array-to-split-string-using-different-delimiters/
SELECT
a[1] AS DiskInfo
,a[2] AS DiskNumber
,a[3] AS MessageKeyword
FROM (
SELECT regexp_split_to_array('Postgres Disk information , disk 2 , failed', ',')
) AS dt(a)
You can use the ANY operator in the JOIN condition:
select *
from table1 t1
join table2 t2 on t2.type = any (t1.type);
Note that if the types in the table1 match multiple rows in table2, you would get duplicates (from table1) because that's how a join works. Maybe you want an EXISTS condition instead:
select *
from table1 t1
where exists (select *
from table2 t2
where t2.type = any(t1.type));
The same name may appear in multiple rows of table1. I would like to enumerate all names in sequential order 1, 2, ... One way to do so is to
create new table with name as primary key and id as serial type.
Select name from table1 and insert it into table2 only when it doesn't exist
table1 (name vchar(50), ...)
table2 (name vchar(50) primary key, id serial)
insert into table2(name)
select name
from table1 limit 9
where not exists (select name from table2 where name = table1.name)
This doesn't work. How to fix it?
Just select distinct values:
insert into table2(name)
select distinct name
from table1
order by name;
I need advice on doing a JOIN with PostgreSQl. I want to take the sum (or number of times id 1 is entered) of a single id and place it into a new column in table b.
Table a
id username comment
1 Bob Hi
2 Sally Hello
1 Bob Bye
Table b
id something total_comments
1 null 2
Create a trigger for insert, update, delete on the Table a to select the sum and update in Table b
You could use SELECT INTO if table_b doesn't already exist.
SELECT
id
, NULL AS something
, COUNT(comment) AS total_comments
INTO table_B
FROM table_a
GROUP BY id
Or INSERT INTO if table_b does exist.
INSERT INTO table_b (id, something, total_comments)
SELECT
id
, NULL AS something
, COUNT(comment) AS total_comments
FROM table_a
GROUP BY id
I am using Postgresql and need to query two tables like this:
Table1
ID Bill
A 1
B 2
B 3
C 4
Table2
ID
A
B
I want a table with all the columns in Table1 but keeping only the records with IDs that are available in Table2 (A and B in this case). Also, Table2's ID is unique.
ID Bill
A 1
B 2
B 3
Which join I should use or if I can use WHERE statement?
Thanks!
SELECT Table1.*
FROM Table1
INNER JOIN Table2 USING (ID);
or
SELECT *
FROM Table1
WHERE ID IN (SELECT ID FROM Table2);
but the first one is better for performance reason.
SELECT *
FROM Table1
WHERE EXISTS (
SELECT 1 FROM Table2 WHERE Table2.ID = Table1.ID LIMIT 1
)