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Python and SQL Query

Hello I need help with Python and SQL.
I have 2 tables:
users_table:
userid | name |
tasks_table:
userid | name | date
What I need it's get users ids from 1st table:
SELECT userid FROM users_table
And use those userids to make SELECT from second table:
SELECT count(date) from tasks_table WHERE userid=xxx
How can I do it with python? I'm tried to use loop but it didn't work for some reason maybe I did something wrong.
I'll be grateful for any help.
Thanks!

SELECT U.USER_ID,COUNT(T.DATE)AS CNT
FROM USERS_TABLE AS U
LEFT JOIN TASKS_TABLE AS T ON U.USER_ID=T.USER_ID
GROUP BY U.USER_ID

How to create a filter in SQLite database across multiple tables?

I am looking for a way to create a number of filters across a few tables in my SQL database. The 2 tables I require the data from are Order and OrderDetails.
The Order table is like this:
------------------------------------
| OrderID | CustomerID | OrderDate |
------------------------------------
The OrderDetails table is like this:
----------------------------------
| OrderID | ProductID | Quantity |
----------------------------------
I want to make it so that it counts the number of instances a particular OrderID pops up in a single day. For example, it will choose an OrderID in Order and then match it to the OrderIDs in OrderDetails, counting the number of times it pops up in OrderDetails.
-----------------------------------------------------------
| OrderID | CustomerID | OrderDate | ProductID | Quantity |
-----------------------------------------------------------
The code I used is below here:
# Execute SQL Query (number of orders made on a particular day entered by a user)
cursor.execute("""
SELECT 'order.*', count('orderdetails.orderid') as 'NumberOfOrders'
from 'order'
left join 'order'
on ('order.orderid' = 'orderdetais.orderid')
group by
'order.orderid'
""")
print(cursor.fetchall())
Also, the current output that I get is this when I should get 3:
[('order.*', 830)]

Your immediate problem is that you are abusing the use of single quotes. If you need to quote an identifiers (table name, column name and the-like), then you should use double quotes in SQLite (this actually is the SQL standard). And an expression such as order.* should not be quoted at all. You are also self-joining the orders table, while you probably want to bring the orderdetails.
You seem to want:
select
o.orderID,
o.customerID,
o.orderDate,
count(*) number_of_orders
from "order" o
left join orderdetails od on od.orderid = o.orderid
group by o.orderID, o.customerID, o.orderDate
order is a language keyword, so I did quote it - that table would be better named orders, to avoid the conflicting name. Other identifiers do not need to be quoted here.
Since all you want from orderdetails is the count, you could also use a subquery instead of aggregation:
select
o.*,
(select count(*) from orderdetails od where od.orderid = o.oderid) number_of_orders
from "order" o

SQL - Possible to Auto Increment Number but with leading zeros?

Our IDs look something like this "CS0000001" which stands for Customer with the ID 1. Is this possible to to with SQL and Auto Increment or do i need to to that in my GUI ?
I need the leading zeroes but with auto incrementing to prevent double usage if am constructing the ID in Python and Insert them into the DB.
Is that possible?

You have few choices:
Construct the CustomerID in your code which inserts the data into
the Customer table (=application side, requires change in your code)
Create a view on top of the Customer-table that contains the logic
and use that when you need the CustomerID (=database side, requires change in your code)
Use a procedure to do the inserts and construct the CustomerID in
the procedure (=database side, requires change in your code)

Possible realization.
Create data table
CREATE TABLE data (id CHAR(9) NOT NULL DEFAULT '',
val TEXT,
PRIMARY KEY (id));
Create service table
CREATE TABLE ids (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
Create trigger which generates id value
CREATE TRIGGER tr_bi_data
BEFORE INSERT
ON data
FOR EACH ROW
BEGIN
INSERT INTO ids () VALUES ();
SET NEW.id = CONCAT('CS', LPAD(LAST_INSERT_ID(), 7, '0'));
DELETE FROM ids;
END
Create trigger which prohibits id value change
CREATE TRIGGER tr_bu_data
BEFORE UPDATE
ON data
FOR EACH ROW
BEGIN
SET NEW.id = OLD.id;
END
Insert some data, check result
INSERT INTO data (val) VALUES ('data-1'), ('data-2');
SELECT * FROM data;
id | val
:-------- | :-----
CS0000001 | data-1
CS0000002 | data-2
Try to update, ensure id change prohibited
UPDATE data SET id = 'CS0000100' WHERE val = 'data-1';
SELECT * FROM data;
id | val
:-------- | :-----
CS0000001 | data-1
CS0000002 | data-2
Insert one more data, ensure enumeration continues
INSERT INTO data (val) VALUES ('data-3'), ('data-4');
SELECT * FROM data;
id | val
:-------- | :-----
CS0000001 | data-1
CS0000002 | data-2
CS0000003 | data-3
CS0000004 | data-4
Check service table is successfully cleared
SELECT COUNT(*) FROM ids;
| COUNT(*) |
| -------: |
| 0 |
db<>fiddle here
Disadvantages:
Additional table needed.
Generated id value edition is disabled (copy and delete old record must be used instead, custom value cannot be set).

POSTGRES: Inner join with removing id prefix

I have two tables, one is an instrument_static table that looks like this
epic| name | Updated
-----------------------------------
ABC | Google |2017-02-03
The other table is market_data that looks like this
epic | name | Updated
-----------------------------------
MARKET:ABC | Google |2017-02-03
I want to join both tables using the epic but note the epic in market_data will always be prefixed with "MARKET:".Can someone kindly assist
I believe this query is identical to this one:
Sql Inner join with removing id prefix
However, as I am dealing with Postgress I have read charindex is not a supported function.
This is what I have managed to come up with so far which currently brings back an error:
SELECT * FROM instrument_static s
INNER JOIN market_data m ON
substring(m.epic, charindex(':', M.epic)+1, len(m.epic)) = s.epic

You can use string concatenation in the join clause:
select . . .
from instrument_static ins join
market_data md
on md.epic = 'MARKET:' || ins.epic and
md.name = ins.name and
md.updated = ins.updated;
There are similar methods to accomplish this using split(), like, regular expression matching, and so on.

I want make join 2 tables but on 2 things not the typical same, like slug and path , slug abc , and path /article

I have 2 tables one name log contains (path, and log id, etc)
second table name articles contain (slug, id, title)
I want to make a query make join on articles.slug on a log. path
(the problem there path = /articles/slug)
how I make this join
I found pattern called '% %' I tried to use it in join but I don't know how like join on log.path = '/article/' + log.slug
log.path log.count(path)view article.slug
-------------------------------------+- -------|--------------------
/ | 479121 |
/article/candidate-is-jerk | 338647 | candidate-is-jerk
/article/bears-love-berries | 253801 | bears-love-berries
/article/bad-things-gone | 170098 | bad-things-gone
I need make join on this log.path = '/article/' + log.slug

You can express this join in SQL as:
from log l join
article a
on l.path = concat('/article/', a.slug);
or (using standard syntax):
from log l join
article a
on l.path = '/article/' || a.slug;
The second form will handle null values, by ignoring them. The first will (generally but it might depend on the database) return null if either value is null.

You can do join like this
on log.path like concat('%article%',article.slug);