CREATE TABLE ACCOUNT_STATE (
    CODE          INTEGER NOT NULL,
    ACCOUNTCODE  BIGINT NOT NULL,
    ENDDATE     DATE,
.......
);

ALTER TABLE ACCOUNT_STATE ADD CONSTRAINT PK_ACCOUNT_STATE PRIMARY KEY (CODE);

CREATE DESCENDING INDEX ACCOUNT_STATE_ACC_ED_DESC ON ACCOUNT_STATE (ACCOUNTCODE, ENDDATE);

 select *
  from Account_State
  where Accountcode = :IAccount
    and (Enddate = :Idate1 or Enddate = :Idate2)

CREATE ASCENDING INDEX ACCOUNT_STATE_ACC_ED_DESC ON ACCOUNT_STATE (ACCOUNTCODE, ENDDATE);

select *
  from Account_State
  where (Accountcode = :IAccount and Enddate = :Idate1) or
  (Accountcode = :IAccount and Enddate = :Idate2)

 select *
   from Account_State
  where Accountcode = 240472
    and (Enddate = date '01.01.2013' or Enddate = date '31.01.2013')

 select *
   from Account_State
  where (Accountcode = 240472 and Enddate = date '01.01.2013') OR
           (Accountcode = 240472 and Enddate = date '31.01.2013')

SELECT SEG.RDB$INDEX_NAME AS INDEX_NAME,
       SEG.RDB$FIELD_NAME AS FIELD_NAME,
       SEG.RDB$STATISTICS AS STAT
FROM RDB$INDEX_SEGMENTS SEG
WHERE SEG.RDB$INDEX_NAME = 'ACCOUNT_STATE_ACC_ED_DESC'
UNION ALL
SELECT I.RDB$INDEX_NAME AS INDEX_NAME,
       NULL AS FIELD_NAME,
       I.RDB$STATISTICS AS STAT
FROM RDB$INDICES I
WHERE I.RDB$INDEX_NAME = 'ACCOUNT_STATE_ACC_ED_DESC'

INDEX_NAME	             FIELD_NAME	                 STAT
-----------------------------------------------------------------
ACCOUNT_STATE_ACC_ED_DESC	ENDDATE    	3.72061185771599E-6
ACCOUNT_STATE_ACC_ED_DESC	ACCOUNTCODE	7.78846515459009E-6
ACCOUNT_STATE_ACC_ED_DESC              		3.72061185771599E-6

CREATE TABLE ACCOUNT_SERVICE (
    CODE              INTEGER NOT NULL ,
    ACCOUNTCODE       BIGINT NOT NULL ,
    SERVICE         INTEGER NOT NULL,
    ACCOUNT_PIPECODE   INTEGER NOT NULL ,
    ENDDATE        DATE,
.......
);

ALTER TABLE ACCOUNT_SERVICE ADD CONSTRAINT PK_ACCOUNT_SERVICE PRIMARY KEY (CODE);

CREATE DESCENDING INDEX ACCOUNT_SERVICE_ACC_ENDDATE ON ACCOUNT_SERVICE (ACCOUNTCODE, ACCOUNT_PIPECODE, ENDDATE);
CREATE INDEX ACCOUNT_SERVICE_PIPE_SERVICE ON ACCOUNT_SERVICE (ACCOUNT_PIPECODE, SERVICE);

select *
  from Account_Service
  where Accountcode = 251696
    and Account_Pipecode = 307817
    and (Enddate = date '01.01.2013' or Enddate = date '31.01.2013')

select *
  from Account_Service
  where Accountcode = 251696
    and Account_Pipecode = 307817
    and Enddate = date '01.01.2013'