text: --  @testpoint:openGauss关键字matched(非保留)，同时作为表名和列名带引号，与union结合查询合并两个SELECT 语句查询
  
  drop table if exists "matched";
  create table "matched"(
  	c_id int, c_int int, c_integer integer, c_bool int, c_boolean int, c_bigint integer,
  	c_real real, c_double real,
  	c_decimal decimal(38), c_number number(38), c_numeric numeric(38),
  	c_char char(50) default null, c_varchar varchar(20), c_varchar2 varchar2(4000),
  	c_date date, c_datetime date, c_timestamp timestamp,
  	"matched" varchar(100) default 'matched'
  )
  PARTITION BY RANGE (c_integer)
  (
  	partition P_20180121 values less than (0),
  	partition P_20190122 values less than (50000),
  	partition P_20200123 values less than (100000),
  	partition P_max values less than (maxvalue)
  );
  
  insert into "matched"(c_id,"matched") values(1,'hello');
  insert into "matched"(c_id,"matched") values(2,'china');
  insert into "matched"(c_id,"matched") values(3,'gauss');
  ---两个select语句合并查询，查询结果显示hello、china、gauss，对括号中的select子句取limit 2
  select "matched" from "matched" where "matched"='hello'
  union all (select "matched" from "matched" where "matched"!='hello' order by "matched" limit 2);
  
  drop table "matched";