Convert mysql query to sqlite - mysql

Question

I am new to sqlite3.I am currently using mysql. But I will be migrating it to sqlite3.
I am calculating month end balance
SELECT c.country,
Date_format(Last_day(Str_to_date(dt.date, '%m/%d/%Y')), '%Y/%m/%d')
AS Month_End_Balance,
Sum(dt.amount) AS in_Euro
FROM deposit_transactions AS dt
LEFT JOIN customers AS c
ON c.customer_id = dt.customer_id
GROUP BY c.country,
Month_End_Balance
order by Month_End_Balance desc
Need help in converting it to sqlite
Question
Need help in Last_Day function alternative in sqlite

Answer 1

Refer below query for SQLITE -
Please make adjustment as per needed date format.
with new_dep_trx as (
select deposit_id,customer_id,
transaction_type,amount,currency,
case when (length(dt.date)=8 or length(dt.date)=9) and instr(substr(dt.date,1,2),'/')>0
then
date(substr(dt.date,length(dt.date)-3,4)||'-0'||substr(dt.date,1,1)||'-0'||substr(dt.date,3,1))
when length(dt.date)=9 and instr(substr(dt.date,1,2),'/')=0
then
date(substr(dt.date,length(dt.date)-3,4)||'-'||substr(dt.date,1,2)||'-0'||substr(dt.date,4,1))
else
date(substr(dt.date,length(dt.date)-3,4)||'-'||substr(dt.date,1,2)||'-'||substr(dt.date,4,2)) end date_col
from deposit_transactions dt
)
select
c.country,
strftime('%Y-%m',dt.date_col) as month,
strftime('%m/%d/%Y',date(dt.date_col,'start of month','+1 month','-1 day')) as last_day_of_month,
strftime('%Y/%m/%d',date(dt.date_col,'start of month','+1 month','-1 day')) as last_day_of_month_your_format,
SUM(
dt.amount *
(CASE WHEN dt.currency = 'GBP' THEN .85 ELSE 1 END) *
(CASE WHEN dt.transaction_type = 'pay_in' THEN 1 ELSE -1 END)
) amount_eur
FROM new_dep_trx dt
LEFT JOIN customers c ON c.customer_id = dt.customer_id
GROUP BY c.country, last_day_of_month_your_format;
Modified DB fiddle.

Answer 2

First, you must update the column date of the table deposit_transactions so that it has the format YYYY-mm-dd the only text date format that you can use with SQLite's datetime functions:
UPDATE deposit_transactions
SET date = SUBSTR(date, -4) || '-' ||
printf('%02d', date + 0) || '-' ||
printf('%02d', SUBSTR(date, INSTR(date, '/') + 1, 2) + 0);
Now, you can use the function date() to get the last day of each month with:
date(date, 'start of month', '+1 month', '-1 day')
So, your query should be:
SELECT c.country,
date(dt.date, 'start of month', '+1 month', '-1 day') AS Month_End_Balance,
SUM(dt.amount *
CASE WHEN dt.currency = 'GBP' THEN .85 ELSE 1 END *
CASE WHEN dt.transaction_type = 'pay_in' THEN 1 ELSE -1 END
) AS amount_eur
FROM deposit_transactions AS dt LEFT JOIN customers AS c
ON c.customer_id = dt.customer_id
GROUP BY c.country, Month_End_Balance
ORDER BY Month_End_Balance DESC;
If you want to format the dates of the resultset to mm/dd/YYYY and sort properly by the date and not the formatted date which would sort incorrectly:
SELECT c.country,
strftime('%m/%d/%Y', date(dt.date, 'start of month', '+1 month', '-1 day')) AS Month_End_Balance,
SUM(dt.amount *
CASE WHEN dt.currency = 'GBP' THEN .85 ELSE 1 END *
CASE WHEN dt.transaction_type = 'pay_in' THEN 1 ELSE -1 END
) AS amount_eur
FROM deposit_transactions AS dt LEFT JOIN customers AS c
ON c.customer_id = dt.customer_id
GROUP BY c.country, date(dt.date, 'start of month', '+1 month', '-1 day')
ORDER BY date(dt.date, 'start of month', '+1 month', '-1 day') DESC;
See the demo.