How to collect all SQL statement executed by Schema.

1. Set AUDIT_TRAIL parameter value db (Default) so that audit information will written into database (SYS.AUD$).
2. Create Schema and define audit policy.
3. Create and Enable fine grained auditing.
4. Collect all SQL Statement from sys.FGA_LOG$ table.
5. Purge all Audit information.
6. Drop fine grained auditing.
7. Scripts for enable fine grained auditing for all objects of schema.

1. 
SQL> show parameter audit_trail

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
audit_trail                          string      DB
SQL>

2.
GRANT CONNECT, RESOURCE, DBA TO AUDIT_USER IDENTIFIED BY AUDIT_USER;

AUDIT ALL BY AUDIT_USER BY ACCESS;
AUDIT SELECT TABLE, UPDATE TABLE, INSERT TABLE, DELETE TABLE BY AUDIT_USER BY ACCESS;
AUDIT EXECUTE PROCEDURE BY AUDIT_USER BY ACCESS;
3.
--- Create Fine Grained Auditing
BEGIN
  DBMS_FGA.ADD_POLICY(
    OBJECT_SCHEMA   => 'AUDIT_USER',
    OBJECT_NAME     => 'TEST_DATA',
    POLICY_NAME     => 'AUDIT_USER_P',
    AUDIT_CONDITION => NULL,
    AUDIT_COLUMN    => NULL,
    STATEMENT_TYPES => 'SELECT,INSERT,UPDATE,DELETE');
END;
--- Enable Fine Grained Auditing
BEGIN

DBMS_FGA.ENABLE_POLICY (
OBJECT_SCHEMA    =>  'AUDIT_USER',
OBJECT_NAME      =>  'TEST_DATA',
POLICY_NAME      =>  'AUDIT_USER_P',
ENABLE           =>   TRUE);

END;

4.
--- Find all SQL Statement using the following Query. You can also store all SQL Statement in your own table using the Second query.

SELECT LSQLTEXT, LSQLBIND,NTIMESTAMP#
FROM FGA_LOG$;

CREATE TABLE SQL_STATEMENT
AS
SELECT LSQLTEXT, LSQLBIND,NTIMESTAMP#
FROM FGA_LOG$;

SELECT *
FROM FGA_LOG$;

5. 
--- Auditing information can be purge by truncate SYS.AUD$ and sys.FGA_LOG$ table. This is manual purge. Automated purge policy can define so that Oracle will automatically purge all audit information by using scheduler.

TRUNCATE TABLE SYS.AUD$ ;
TRUNCATE TABLE sys.FGA_LOG$;

6. 
BEGIN
  DBMS_FGA.drop_policy(
    object_schema   => 'AUDIT_USER',
    object_name     => 'TEST_DATA',
    policy_name     => 'AUDIT_USER_P');
END;

7. 
CREATE OR REPLACE PROCEDURE SP_AUDIT_SCHEMA_ACTIVITY (
   P_IN_SCHEMA_NAME IN VARCHAR2)
IS
   W_POLICY_NAME   VARCHAR2 (100);

   CURSOR CUR_TABLE_LIST
   IS
      SELECT OWNER, TABLE_NAME
        FROM ALL_TABLES
       WHERE OWNER = P_IN_SCHEMA_NAME;

BEGIN
   FOR IDX IN CUR_TABLE_LIST
   LOOP
      W_POLICY_NAME := IDX.OWNER || '_' || IDX.TABLE_NAME;
   
      IF LENGTH(W_POLICY_NAME)>30 THEN
       W_POLICY_NAME:=IDX.TABLE_NAME;
      END IF;

      BEGIN
         DBMS_FGA.ADD_POLICY (
            OBJECT_SCHEMA     => IDX.OWNER,
            OBJECT_NAME       => IDX.TABLE_NAME,
            POLICY_NAME       => W_POLICY_NAME,
            AUDIT_CONDITION   => NULL,
            AUDIT_COLUMN      => NULL,
            STATEMENT_TYPES   => 'SELECT,INSERT,UPDATE,DELETE');
      EXCEPTION
         WHEN OTHERS
         THEN
            DBMS_OUTPUT.PUT_LINE (W_POLICY_NAME||' >> '||SQLERRM);
      END;


      BEGIN
         DBMS_FGA.ENABLE_POLICY (OBJECT_SCHEMA   => IDX.OWNER,
                                 OBJECT_NAME     => IDX.TABLE_NAME,
                                 POLICY_NAME     => W_POLICY_NAME,
                                 ENABLE          => TRUE);
      EXCEPTION
         WHEN OTHERS
         THEN
            DBMS_OUTPUT.PUT_LINE (W_POLICY_NAME||' >> '||SQLERRM);
      END;
   END LOOP;
END;

CREATE OR REPLACE PROCEDURE SP_DROP_AUDIT_POLICY (
   P_IN_SCHEMA_NAME IN VARCHAR2)
IS
   W_POLICY_NAME   VARCHAR2 (100);

   CURSOR CUR_POLICY_LIST
   IS
      SELECT OBJECT_SCHEMA, OBJECT_NAME, POLICY_NAME
        FROM DBA_AUDIT_POLICIES
       WHERE OBJECT_SCHEMA = P_IN_SCHEMA_NAME;

BEGIN
   FOR IDX IN CUR_POLICY_LIST
   LOOP
      W_POLICY_NAME := IDX.POLICY_NAME;

      BEGIN
         DBMS_FGA.drop_policy (object_schema   => IDX.OBJECT_SCHEMA,
                               object_name     => IDX.OBJECT_NAME,
                               policy_name     => W_POLICY_NAME);
      END;
   END LOOP;
END;


EXEC SP_AUDIT_SCHEMA_ACTIVITY('SCHEMA_NAME');

EXEC SP_DROP_AUDIT_POLICY('SCHEMA_NAME');

Reference

https://oracle-base.com/articles/10g/auditing-10gr2

https://oracle-base.com/articles/11g/auditing-enhancements-11gr2