Select all rows from 2 tables where field =? - php

Question

Quite simply, I need an MySQL statement that selects all the rows from 2 different tables where userId = 1. Here's the statement I have but it doesn't work. It returns results from table 1 (The left table):
$transactionsQ = $db->query("select e.sender, e.amount, e.timestamp, s.sender, s.recipient, s.amount, s.timestamp from ethTransactions as e, sofTransactions as s where e.userId = ? or s.userId = ?", [$currentUser->id, $currentUser->id]);
table1 (ethTransactions) is like:
|id|userId|sender|amount|timestamp|
table2 (sofTransactions) is like:
|id|userId|sender|recipient|amount|timestamp|
some data on ethTransactions:
1|12|ajdoaidjoiwjdaq|0.03222|2017-11-08 03:09:11
some data on sofTransactions:
1|12|opiyptropyirpyi|dqwuebhdnwq|1.02223|2017-10-08 04:09:11
What I want to return since both have the same userId:
|id|userId|sender |recipient |amount |timestamp |
|1 |12 |ajdoaidjoiwjdaq| |0.03222|2017-11-08 03:09:11|
|1 |12 |opiyptropyirpyi|dqwuebhdnwq|1.02223|2017-10-08 04:09:11|

Answer 1

You should use LEFT JOIN to do that.
SELECT
e.sender as e_sender,
e.amount as e_amount,
e.timestamp as e_timestamp,
s.sender as s_sender,
s.recipient as s_recipient,
s.amount as s_amount,
s.timestamp as as_timestamp
FROM
ethTransactions e
LEFT JOIN
sofTransactions s ON s.userId = e.userId
WHERE
e.userId = ?

Answer 2

SELECT column_names(s) FROM table1 AS t1 **INNER JOIN** table2 AS t2
ON t1.userId = t2.userId WHERE t1.userId=1;

Answer 3

There is something strange about the structure of your database. A JOIN on userid seems natural, but it potentially joins rows from one table with rows from the other table that have different sender columns. This would imply that you are joining data items that do not belong together.
My answer to your question is: redesign your table structure because you are going to break one of the main rules of relational databases - most likely, duplicating data.