postgresql 函数demo

create or replace function refresh_product_usage() returns void as  $$
declare
	rec record;
	sub_rec record;
	init_pro_id integer;
	parent_product_id integer;
	now_bom_id integer;
	total_product_qty float;
	cinsider_efficiency boolean:=true;

begin
        TRUNCATE TABLE  product_usage;
	for rec in select id,bom_id,product_id,product_qty,product_efficiency from mrp_bom where bom_id is not null loop
		now_bom_id:=rec.bom_id;
		total_product_qty:= rec.product_qty;
		if cinsider_efficiency then
			total_product_qty = total_product_qty/rec.product_efficiency;
		end if;
		loop
			for sub_rec in select product_id as parent_product_id from mrp_bom where id =now_bom_id loop
				parent_product_id:=sub_rec.parent_product_id;
			end loop;

			if not exists(select id from mrp_bom where bom_id is not null and product_id = parent_product_id ) then --(no record)-->root bom
				if exists(select id from product_usage where bom_id = now_bom_id and product_id = rec.product_id) then
					update product_usage set product_qty = product_qty + total_product_qty where  bom_id = now_bom_id and product_id = rec.product_id;
				else
					insert into product_usage(bom_id,product_id,product_qty) values(now_bom_id, rec.product_id, total_product_qty);
				end if;
				exit;
			else
				for sub_rec in select bom_id,product_qty,product_efficiency from mrp_bom where bom_id is not null and product_id = parent_product_id limit 1 loop
					now_bom_id:=sub_rec.bom_id;
					total_product_qty = total_product_qty* sub_rec.product_qty;
					if cinsider_efficiency then
						total_product_qty = total_product_qty/sub_rec.product_efficiency;
					end if;
				end loop;
			end if;

		end loop;

	end loop;
end;
$$ LANGUAGE plpgsql;

　

实际上，本来打算只写一个sql代码块，也就是只要以下部分：

declare
	rec record;
	sub_rec record;
	init_pro_id integer;
	parent_product_id integer;
	now_bom_id integer;
	total_product_qty float;
	cinsider_efficiency boolean:=true;

begin
        TRUNCATE TABLE  product_usage;
	for rec in select id,bom_id,product_id,product_qty,product_efficiency from mrp_bom where bom_id is not null loop
		now_bom_id:=rec.bom_id;
		total_product_qty:= rec.product_qty;
		if cinsider_efficiency then
			total_product_qty = total_product_qty/rec.product_efficiency;
		end if;
		loop
			for sub_rec in select product_id as parent_product_id from mrp_bom where id =now_bom_id loop
				parent_product_id:=sub_rec.parent_product_id;
			end loop;

			if not exists(select id from mrp_bom where bom_id is not null and product_id = parent_product_id ) then --(no record)-->root bom
				if exists(select id from product_usage where bom_id = now_bom_id and product_id = rec.product_id) then
					update product_usage set product_qty = product_qty + total_product_qty where  bom_id = now_bom_id and product_id = rec.product_id;
				else
					insert into product_usage(bom_id,product_id,product_qty) values(now_bom_id, rec.product_id, total_product_qty);
				end if;
				exit;
			else
				for sub_rec in select bom_id,product_qty,product_efficiency from mrp_bom where bom_id is not null and product_id = parent_product_id limit 1 loop
					now_bom_id:=sub_rec.bom_id;
					total_product_qty = total_product_qty* sub_rec.product_qty;
					if cinsider_efficiency then
						total_product_qty = total_product_qty/sub_rec.product_efficiency;
					end if;
				end loop;
			end if;

		end loop;

	end loop;
end;

　

但奇怪的是会报很多莫名其妙的语法错误：

貌似无法识别很多诸如 record / open 之类的关键字。

郁闷之下写了个函数。

postgresql 用于sql debug输出可以用：raise notice 'your_message;%s'%your_message_var

然后游标的概念弱化了，与其用cursor，不如直接用 for rec in select .... loop  ....  end loop;

有点小遗憾没有找到从结果集里直接赋值的方法。

动态执行sql语句使用DO/EXECUTE