You need to query the data dictionary, specifically the USER_CONS_COLUMNS view to see the table columns and corresponding constraints: SELECT * FROM user_cons_columns WHERE table_name=”<your table name>”; FYI, unless you specifically created your table with a lower case name (using double quotes) then the table name will be defaulted to upper case so ensure it … Read more
If you want just a first selected row, you can: select fname from MyTbl where rownum = 1 You can also use analytic functions to order and take the top x: select max(fname) over (rank() order by some_factor) from MyTbl
I had this issue and the fix was to make sure in tnsnames.ora the SERVICE_NAME is a valid service name in your database. To find out valid service names, you can use the following query in oracle: select value from v$parameter where name=”service_names” Once I updated tnsnames.ora to: TEST = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS … Read more