H2 not recognising regexp_like

问题

I have a query written to run on an Oracle database which uses the function REGEXP_LIKE to filter some rows from the query. The specific function call is

regexp_like(col1, '[^[:alpha:]]')

The problem is when I run the query on H2 I get the following error:

org.h2.jdbc.JdbcSQLException: Function "REGEXP_LIKE" not found

If I run the query directly on the Oracle database using the SQLDeveloper tool it returns as expected.

Any ideas what could be causing this?

回答1:

H2 doesn't have a function called regexp_like. But you could create one using a user defined function:

create alias regexp_like as 
$$ boolean regexpLike(String s, String p) { return s.matches(p); } $$;

drop table test;
create table test(id int, name varchar(2555));
insert into test values(1, 'Steven');
insert into test values(2, 'Stefan');
select * from test where regexp_like(name, '^Ste(v|ph)en$');

回答2:

See the excellent documentation.

col REGEXP '[^[:alpha:]]'

In general SQL variants either use a function or named operator.

Whether the above specific regex works I do not know. One should be able to rely on java regular expressions.

回答3:

Here is a slightly improved version of the H2 user function by Thomas Mueller which supports flags and NULL values:

create alias regexp_like as
$$ boolean regexpLike(String s, String p, String flags) {
    if(null == s) return false;
    if(null != flags) { p = "(?" + flags + ")" + p; }
    java.util.regex.Pattern compiled = java.util.regex.Pattern.compile(p);
    return compiled.matcher(s).find();
} $$