I'm now trying to write query to make new table name 'want' with the data from table 'customer_tb' and 'study_history'.
For each table, primary key is colored in yellow.
I was trying to write query, but duplicate customer_id appears.
I wonder how I can get rid of duplicate values and make a table in the form of 'want' below.
In MySQL there is an option of setting an alias to a key or a table, that way you can use two different keys with similar names from two different tables and rename them so they do not clash with each other.
select id as id_A from tableA join select id as id_B from tableB
You can also directly reference the key from the table you want to reference it to by using the table name, a period and then the key name like so:
tableA.id
If you are not using MySQL I am certain there are similar functionalities in other sql languages and servers.
Good Luck!