SQL> CREATE TABLE t (x VARCHAR2(30));
  
Table created.
  
SQL> INSERT INTO t VALUES ('Test1');
SQL> INSERT INTO t VALUES ('test 2');
SQL> INSERT INTO t VALUES ('TEST NUMBER THREE');
SQL> INSERT INTO t VALUES ('4th Test');
SQL> INSERT INTO t VALUES ('test no five');
SQL> COMMIT;
  
Commit complete.
  
SQL> SELECT t.x
  2  ,      UPPER(SUBSTR(t.x,1,1))
  3         || LOWER(SUBSTR(t.x,2)) only_first_letter_capitalized
  4  FROM   t
  5  /
  
X                              ONLY_FIRST_LETTER_CAPITALIZED
------------------------------ ------------------------------
Test1                          Test1
test 2                         Test 2
TEST NUMBER THREE              Test number three
4th Test                       4th test
test no five                   Test no five
  
SQL>