imos=# select 'hello' ~ '[\u2e80-\ua4cf]|[\uf900-\ufaff]|[\ufe30-\ufe4f]';
 ?column?
----------
 f
(1 row)
imos=#
imos=# select 'hello中國' ~ '[\u2e80-\ua4cf]|[\uf900-\ufaff]|[\ufe30-\ufe4f]';
 ?column?
----------
 t
(1 row)

postgres=# select position('aa' in 'abcd');
 position 
----------
 0
(1 row)
postgres=# select position('ab' in 'abcd');
 position 
----------
 1
(1 row)
postgres=# select position('ab' in 'abcdab');
 position 
----------
 1
(1 row)

postgres=# select strpos('abcd','aa');
 strpos 
--------
 0
(1 row)
postgres=# select strpos('abcd','ab');
 strpos 
--------
 1
(1 row)
postgres=# select strpos('abcdab','ab');
 strpos 
--------
 1
(1 row)

postgres=# select 'abcd' ~ 'aa';
 ?column? 
----------
 f
(1 row)
postgres=# select 'abcd' ~ 'ab';
 ?column? 
----------
 t
(1 row)
postgres=# select 'abcdab' ~ 'ab';
 ?column? 
----------
 t
(1 row)

postgres=# select regexp_split_to_array('abcd','') @> array['b','e'];
 ?column? 
----------
 f
(1 row)
postgres=# select regexp_split_to_array('abcd','') @> array['a','b'];
 ?column? 
----------
 t
(1 row)

postgres=# select regexp_split_to_array('abcd','') @> array['a','a'];
 ?column? 
----------
 t
(1 row)
postgres=# select regexp_split_to_array('abcd','') @> array['a','c'];
 ?column? 
----------
 t
(1 row)
postgres=# select regexp_split_to_array('abcd','') @> array['a','c','a','c'];
 ?column? 
----------
 t
(1 row)