Firebird 3.0

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select rdb$get_context('SYSTEM', 'ENGINE_VERSION') as version
     , rdb$character_set_name
from rdb$database;


VERSION
RDB$CHARACTER_SET_NAME


3.0.10
UTF8


create table exdata (
  id integer constraint pk_exdata primary key,
  colval varchar(50)
)
insert into exdata (id, colval) values (1, 'a')
1 rows affected

insert into exdata (id, colval) values (2, 'b')
1 rows affected

execute block
  returns (id integer, colval varchar(50))
as
  declare c cursor for (select id, colval from exdata);
begin
  open c;
  fetch c;
  id = c.id;
  colval = c.colval;
  suspend;
  update exdata set colval = 'b' where current of c;
  suspend;
  id = c.id;
  colval = c.colval;
  close c;
  suspend;
end


ID
COLVAL


1
a

1
a

1
b