Query result is incorrect when the regexp is used in where condition

[sunsun314]

• dble version： 2.19.5.0
• schema.xml

 <schema name="schema1" sqlMaxLimit="100" dataNode="dn1">
    </schema>
    <schema name="schema3" sqlMaxLimit="100" dataNode="dn2">
    </schema>
     <schema name="schema2" sqlMaxLimit="100" dataNode="dn3">
    </schema>

• steps：
  schema1
  create table table_a(id int,goods_id varchar(40),city varchar(40));
  insert into table_a values(1,"goods","city");

schema2
create table table_b(id int,goods_id varchar(40));

insert into table_b values(2,"goods");

create table table_c(id int,city varchar(50),wid int);

insert into table_c values(3,"city",4);

schema3

create table table_d(id int,name varchar(100));
insert into table_d values(4,"12345AAA") ;

• expect result：
  select
  dg.id aaaa,
  dgw.id bbbb,
  ew.id cccc
  from schema1.table_a dgw
  inner join schema2.table_b dg
  on dgw.goods_id = dg.goods_id
  left join schema2.table_c dwp
  on dgw.city = dwp.city
  left join schema3.table_d ew
  on ew.id = dwp.wid
  where dgw.id = 1
  and ew.name regexp 'AAA';
  has result
• real result：
  Empty set (0.89 sec)

[wjl1619]

verified on version: 5.6.29-dble-9.9.9.9-02cef4c18ca820fe4401a62c6e6c8053f689b467-20190926091030