Table UNION if Foreign key value is null on table 2 - sql

Question

I have two tables that I'm trying to combine.
Table 1:
FAME_ID, FAME_Emblem_Title, FAME_Category
Table 2:
User_ID, FAME_ID, Times_Received
However, some values does not exist in table 2. For Example:
Table 1: Table 2:
Fame_ID: 1 Fame_ID: null/does not have a value
FAME_Emblem_Title: test1 User_ID: null/does not have a value
FAME_Category: 1 Times_Received: null/does not have a value
Fame_ID: 2 Fame_ID: 2
FAME_Emblem_Title: test2 User_ID: user1
FAME_Category: 1 Times_Received: 1
My goal is to filter the SQL query by Category and user but still display all results that match the first filter even if table 2 does not have any value. By the way my output is in JSON array form.
Result:
[
{
"User_ID": "user1",
"FAME_ID": 1,
"FAME_Category": "1",
"Times_Received": 1,
},
{
"User_ID": "null",
"FAME_ID": 2,
"FAME_Category": "1",
"Times_Received": null,
}
]
I'm honestly not sure if this is possible. Any help is highly appreciated.Thanks!

Answer 1

The JOIN required when you want to return all rows from the LEFT table even if there is no join to the RIGHT table is called a LEFT OUTER JOIN. If there is no match, then the row for the left table will be returned, and the value null substitude for all columns of the missing right table row.
You can achieve the join you want as follows, and output in JSON with:
SELECT t2.User_ID, t1.FAME_ID, t1.FAME_Category, t2.Times_Received
FROM table1 t1 LEFT OUTER JOIN table2 t2 on t1.FAME_ID = t2.FAME_ID
FOR JSON AUTO;