(select concat((select granted_role from user_role_privs where granted_role = 'DBA') from DUAL))

That looks like an Oracle SQL snippet that’s trying to check if the current user has the DBA role by looking in USER_ROLE_PRIVS, and then wrap the result in a CONCAt/concat. As written it has syntax issues.

What the snippet attempts to do

• Query: select granted_role from user_role_privs where granted_role = 'DBA'
  • If the current user has the DBA role, this inner query would return the string 'DBA'.
  • If not, it would return no rows (which in a scalar subquery would raise an error).
• Outer part: concatenate that result (with an incorrect use of CONCAT and misplaced FROM DUAL).

Why it’s not valid as written

• Oracle’s CONCAT function only takes two arguments. The snippet shows a single-argument CONCAT (and the FROM DUAL is not in the right place).
• A scalar subquery (the inner SELECT) must return exactly one row. If there are no rows, Oracle raises ORA-01422 (exact fetch returns no rows).
• The syntax would be rejected by the parser.

Correct ways to express the idea (examples)

1. Just retrieve the role if present (note: may raise ORA-01422 if not present)

• SELECT (SELECT granted_role FROM user_role_privs WHERE granted_role = 'DBA') AS role FROM dual;

2. Concatenate with something else (two-argument CONCAT)

• SELECT CONCAT((SELECT granted_role FROM user_role_privs WHERE granted_role = 'DBA'), ' suffix') AS result FROM dual;
  • Or equivalently: SELECT (SELECT granted_role FROM user_role_privs WHERE granted_role = 'DBA') || ' suffix' AS result FROM dual;

3. Avoid errors when DBA is not present

• Use EXISTS to check presence instead of a scalar subquery:
  • SELECT CASE WHEN EXISTS (SELECT 1 FROM user_role_privs WHERE granted_role = 'DBA') THEN 'DBA' ELSE 'NO_ROLE' END AS status FROM dual;

4. A more robust single query without scalar subquery errors

• SELECT COALESCE(MAX(CASE WHEN granted_role = 'DBA' THEN granted_role END), 'NO_ROLE') AS role FROM user_role_privs;

Notes

• Access to USER_ROLE_PRIVS (a data dictionary/user- privileges view) may require appropriate privileges. If you don’t have access, the query will fail due to permission errors.
• In an exam setting, you might be asked to identify the error, correct the syntax, or explain the behavior if the user has or doesn’t have the DBA role.

If you tell me the exact goal (just detect presence, or return a string to concatenate with something, or handle lack of DBA gracefully), I can tailor the exact corrected query.