Oracle 21c

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create table tw_master (gram_panchayat) as
select 'ABCDEF' from dual union all
select 'B' from dual union all
select 'BA' from dual union all
select 'BAB' from dual union all
select 'BABC' from dual union all
select 'BABCD' from dual union all
select 'BABCDE' from dual union all
select 'BEDCBA' from dual union all
select 'BABCDEF' from dual union all
select 'BABCDEFG' from dual union all
select 'BABCDEFGH' from dual union all
select 'BABCDEFGHI' from dual
12 rows affected

SELECT gram_panchayat FROM tw_master;

GRAM_PANCHAYAT

ABCDEF

B

BA

BAB

BABC

BABCD

BABCDE

BEDCBA

BABCDEF

BABCDEFG

BABCDEFGH

BABCDEFGHI

SELECT SUBSTR(gram_panchayat,1,6) GP FROM tw_master WHERE gram_panchayat LIKE 'B%';

GP

B

BA

BAB

BABC

BABCD

BABCDE

BEDCBA

BABCDE

BABCDE

BABCDE

BABCDE

SELECT gram_panchayat FROM tw_master WHERE gram_panchayat LIKE 'B_____';

GRAM_PANCHAYAT

BABCDE

BEDCBA