Postgresql的pl/pgql用法--将多条执行语句作为一个事务

DO $$  
DECLARE  
	v_id bigint;  
begin  
	--1.
	INSERT INTO r_test_a (name,value,unit,mode,uid,create_ts)  
	SELECT 't_t','',2,extract(epoch from now())::bigint 
	WHERE NOT EXISTS (SELECT id FROM r_test_a WHERE name = 't_t' AND value = '' AND unit = '' AND uid =0);
	--2.
	SELECT id into v_id from r_test_a WHERE name = 't_t' AND value = '' AND unit = '' AND uid = 0;
	--3.
	DELETE FROM r_test_b a WHERE a.obj_id = 'xxx' AND a.file_id = 'ooo' AND a.id IN (SELECT id FROM r_test_a b  WHERE b.name = 't_t' AND b.uid=0); 
	--4.
	INSERT INTO r_test_b (id,obj_id,file_id,create_ts) SELECT v_id,'xxx','ooo',extract(epoch from now())::bigint ;
end 
$$;