Question

I have a WebSQL database which has three tables which all contain id’s and PREFIX_name fields. I need to get all the name fields for single id.

Currently I’m trying following clause:

SELECT A_name FROM TableA WHERE companyId = 1 UNION ALL
SELECT B_name FROM TableB WHERE companyId = 1 UNION ALL
SELECT C_name FROM TableC WHERE companyId = 1

This returns the results object as expected but the field names are wrong:

[{
  "A_name" : "result from TableA",
 },
  "A_name" : "result from TableB",
 },
  "A_name" : "result from TableC"
}];

As you can see, I can’t identify from which table fields are from.

Answer 1

When you UNION results together, the column takes the name given to it in the first query (in this case A_name)

Instead of using UNION ALL, try joining your tables together:

SELECT A.A_name, B.B_name, C.C_name
FROM TableA A
    INNER JOIN TableB B ON A.companyId = B.companyId
    INNER JOIN TableC C ON A.companyId = C.companyId
WHERE A.companyId = 1

This will give you the results on a single row. If you really want the results as seperate rows, you could perhaps select the table name along with the *_name field:

SELECT 'TableA' AS TableName, A_name FROM TableA WHERE companyId = 1 UNION ALL
SELECT 'TableB', B_name FROM TableB WHERE companyId = 1 UNION ALL
SELECT 'TableC', C_name FROM TableC WHERE companyId = 1