Tariq - pls let me know if this is a new or existing (exists in ADS v13) issue.

I was not able to reproduce in 13.0 as well as 14.0. See attached screenshots and the Query Builder File. Can you try my file and see if the error still occurs?

Can you also save the file and attach the .XQB file so that I can reproduce in our labs ?

I copied the same query you mentioned in step 6 but still was not able to replicate

select

        "PRACT123"."S_NAME",

        "PRACT123"."T_ID1",

        "PRACT123"."S_NAME"+ ' ' +"PRACT134"."P_NAME",

        "PRACT134"."T_ID1",

        "PRACT134"."P_NAME" 

from

        "SYSTEM"."PRACT123" "PRACT123" 

                inner join "SYSTEM"."PRACT134" "PRACT134" 

                on "PRACT123"."T_ID1" = "PRACT134"."T_ID1"

We tried executing your file and we are getting the same error. I have attached file as requested

1. Can you send me your .datastudio properties file ?

2. Can you execute the query in a query window and verify if this works ?

3. Can you create 2 tables in a Schema other than SYSTEM and use it in HR or SCOTT and verify if the same error occurs ?

4. Can you try in a different server ?

1)Yes,I have attached my .datastudio properties file as requested.

2)I have executed

select

        "PRACT123"."S_NAME",

        "PRACT123"."T_ID1",

        "PRACT123"."S_NAME"+ ' ' +"PRACT134"."P_NAME",

        "PRACT134"."T_ID1",

        "PRACT134"."P_NAME" 

from

        "SYSTEM"."PRACT123" "PRACT123" 

                inner join "SYSTEM"."PRACT134" "PRACT134" 

                on "PRACT123"."T_ID1" = "PRACT134"."T_ID1" 

query in Query analyser but it display error

"[Error] Script lines: 1-10 ,ORA-01722: invalid number.Script line 4, statement line 4, column 2 "

3)I have created two different tables in  'HR' & 'SCOTT' schema  & checked this operation(+' '+) in it but Query builder shows error as above and I have  attached "HR_schema_new","Scott_Schema" screenshot for this schemas. 

4) I tried same operation in MySql, MSSQL SERVER & ORACLE 11g.  'MSSQL SERVER' display expected result but others don't. I have also used .datastudio file as given by you but that too have same behaviour.

Could there be a difference between how our Oracle 12c is installed and their Oracle 12c?

Our Oracle 12c is installed on 64bit Windows 7. 

Our Oracle 12c is installed on 64 bit Windows 7. I have executed your attached XQB file "jonathan_manually_recreated_12c" but it display error "Invalid number Script line 4, statement line 4, column 2" in Query Builder.

I'm closing this issue b/c  the problem is not with Query Builder nor with Aqua Data Studio. Below are some guidelines to use in the future while debugging issues such as these:

1) The first item to notice is that the server is generating the error message, not ADS. That means a query is being sent to the server.

2) Since a query is being sent to the server, you should turn on SQL Log (Help > SQL Log) and see what query is being sent to the server.

3) You'll notice in this case that the query being sent matches the query being generated by Query Builder. So far so good

4) Next, you can copy the query from the query window and execute it in a query analyzer window. Does the query succeed or does it fail? You'll notice that the query fails with the same error message.

5) Also, when you examine the query, you'll notice that the query itself looks to be valid. 

6) To remove any remaining doubt, you could launch SQL Developer (or some other tool) and try to execute the same query. You should get a similar error message. If you do, then you've properly confirmed that the issue is not with ADS

7) For this specific query, I found an article which might help us understand why the server is generating an error: http://www.orafaq.com/wiki/ORA-01722. Esp take a look in the 'Other Rare Situations'  section. Regardless, I hope you now understand why the problem is not with ADS and that you will apply the same examination process for future issues.