sql脚本函数编写postgresql数据库实现解析_Mysql_

 CREATE SEQUENCE global_id_sequence; CREATE OR REPLACE FUNCTION seq_id(OUT result bigint) AS $$ DECLARE our_epoch bigint := 1314220021721; seq_id bigint; now_millis bigint; -- the id of this DB shard, must be set for each -- schema shard you have - you could pass this as a parameter too shard_id int := 1; BEGIN SELECT nextval('global_id_sequence') % 1024 INTO seq_id; SELECT FLOOR(EXTRACT(EPOCH FROM clock_timestamp()) * 1000) INTO now_millis; result := (now_millis - our_epoch) << 23; result := result | (shard_id << 10); result := result | (seq_id); END; $$ LANGUAGE PLPGSQL; 

 do language plpgsql $$ begin update grade set grade = 90 where sno = '20161003'; end $$