PostgreSQL如何判断内容是数字

CREATE

OR REPLACE FUNCTION isnumeric (txtStr VARCHAR) RETURNS BOOLEAN AS $$

BEGIN

RETURN txtStr ~ '^([0-9]+[.]?[0-9]*|[.][0-9]+)$' ;

END ; $$ LANGUAGE 'plpgsql';

select * from tablename where isnumeric(value)=TRUE