Hi SCN need your help regarding variables in HANA

Actual logic is this

v_BEGIN_DATE    DATE         := '2013-01-01';\\Prior year

v_BEGIN_YYYYMM  VARCHAR(6)   := '201301';

v_BEGIN_YYYY    VARCHAR(4)   := '2013';

v_END_DATE      DATE         := '2014-12-31';\\current year

v_END_YYYYMM    VARCHAR(6)   := '201412';

v_END_YYYY      VARCHAR(4)   := '2014';

This one is static so we have to change it to automatic .I have a Value called PARAM_VALUE in GLOBAL DIM table which hold current year so .

I am trying this logic but unable to achieve it

DECLARE v_BEGIN_DATE DATE;

DECLARE v_BEGIN_YYYYMM  VARCHAR(6);

DECLARE v_BEGIN_YYYY  VARCHAR(4);

DECLARE v_END_DATE DATE;

DECLARE v_END_YYYYMM VARCHAR(6);

DECLARE v_END_YYYY      VARCHAR(4);

v_BEGIN_DATE = SELECT  (YEAR(PARAM_VALUE)-1||'-01-'||'01') FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

v_BEGIN_YYYYMM  = SELECT  (YEAR(PARAM_VALUE)-1||'01') FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

v_BEGIN_YYYY  = SELECT  YEAR(PARAM_VALUE)-1 FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

v_END_DATE  = SELECT  (YEAR(PARAM_VALUE)||'-12-'||'31') FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

v_END_YYYYMM  = SELECT  (YEAR(PARAM_VALUE)||'12') FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

v_END_YYYY  = SELECT  YEAR(PARAM_VALUE) FROM "MGMT_VIS"."GLOBAL_PARAM_DIM";

Am I doing anything wrong here please help me.

Thanks in advance