Ignore duplicate data id in SQL Query? - sql

Question

How do I ignore duplicate data ids from query SQL results:
In this case I tried to combine several tables. Like this scheme that I made:
Transactions
----------------------------------------------------------------------------------------
id
user_id
type
amount
invoice_transaction (Relation to invoice)
created_at
updated_at
Users
----------------------------------------------------------------------------------------
id
name
email
phone
birth
address
picture
created_at
updated_at
Vouchers
----------------------------------------------------------------------------------------
id
code
amount
type
created_at
updated_at
Vouchers Transactions
----------------------------------------------------------------------------------------
id
user_id
voucher_id
created_at
updated_at
invoice
----------------------------------------------------------------------------------------
id
order_data
payment_id
last_total
status
created_at
updated_at
Payment
----------------------------------------------------------------------------------------
id
name
tax
created_at
updated_at
This is a query I made.
SELECT t.id, t.user_id, u1.name, u1.email, v.code, t.amount, t.type, t.created_at, t.invoice_transaction, i.status, p.name,
FROM transactions AS t
INNER JOIN users AS u1 on u1.id = t.user_id
LEFT JOIN vouchers_transaction AS vt on vt.user_id = u1.id
LEFT JOIN vouchers AS v on v.id = vt.voucher_id
LEFT JOIN invoice AS i on i.order_data = t.invoice_transaction
LEFT JOIN payment AS p on p.id = i.payment_id
WHERE t.type = 'buy'
ORDER BY id ASC
In this case I managed to get the data I wanted. But the results of the query contained duplicate transaction id data such as:
Result
---------------------------------------------------------------------------------------------------------------------------
id user_id name email code amount type invoice_transaction status payment_name
1 1 John Doe John#mail.com ycqs1 150 buy SCS11DAS success bank
1 1 John Doe John#mail.com ycqs1 150 buy SCS11DAS success bank
2 1 John Doe John#mail.com n1ksa 200 buy SCS12DAS success bank
Update
It seems like this happened because in the transaction voucher table there is no connection with the transaction table.
Example:
Voucher Transaction
---------------------------------------------------------------------------------------------------------------------------
id user_id voucher_id
1 1 1
2 1 2
3 2 3
Then each transaction will duplicate according to the number of vouchers used in the transaction vouchers, both transactions that use vouchers or not.
I know the best way is to change the database schema. But in this case can it still be done in this case or not?
Results
Result
---------------------------------------------------------------------------------------------------------------------------
id user_id name email code amount type invoice_transaction status payment_name
1 1 John Doe John#mail.com ycqs1 150 buy SCS11DAS success bank
1 1 John Doe John#mail.com sa31a 150 buy SCS11DAS success bank
2 1 John Doe John#mail.com n1ksa 200 buy SCS12DAS success bank
How do I ignore the duplicated transaction id?

Answer 1

Try using group by
SELECT t.id, t.user_id, u1.name, u1.email, v.code, t.amount, t.type, t.created_at, t.invoice_transaction, i.status, p.name,
FROM transactions AS t
INNER JOIN users AS u1 on u1.id = t.user_id
LEFT JOIN vouchers_transaction AS vt on vt.user_id = u1.id
LEFT JOIN vouchers AS v on v.id = vt.voucher_id
LEFT JOIN invoice AS i on i.order_data = t.invoice_transaction
LEFT JOIN payment AS p on p.id = i.payment_id
WHERE t.type = 'buy'
GROUP BY SELECT t.id, t.user_id, u1.name, u1.email, v.code, t.amount, t.type, t.created_at, t.invoice_transaction, i.status, p.name
ORDER BY id ASC

Answer 2

You will always get double ID's because the rows are different. The code and amount columns are all unique and you havent told SQL what to do with those columns. The group by Mahesh showed will work, if you change it to resolve the difference in the code and amount columns.
what amount do you want to see for ID 1? The lowest? highest? average? sum?.
either you have to remove those 2 columns from the query, or provide an aggregate function to resolve what to show

Answer 3

SELECT DISTINCT ON column1, column2, ...
FROM table_name;
The SELECT DISTINCT ON statement is used to return only distinct (different) values.