postgresql中的函数出现问题

在基于Postgresql的SUPABASE函数中,我想写一个函数,将客户的姓名作为输入,然后在函数的主体中实现这样的逻辑,即如果客户尚未创建,则将其插入到客户表中,然后存储其id并创建订单行,如果客户已经存在,则存储其id,然后创建订单

函数如下:

create or replace function FUNC_new_order(name text , qty int)
returns void as 
$$
begin
    declare CSID int ; 
    select customer_id into CSID from customer where customer_name = name ; 
    if NOT FOUND then 
    insert into customer(customer_name) values(name);
    select customer_id into CSID from customer where customer_name = name ; 
    --create order 
    insert into "order"(customer_id , order_qty)values(CSID, qty);

end;
$$
language plpgsql ; 

但在 苏巴色 它返回这个错误:

ERROR:  42601: syntax error at or near "into"
LINE 22:    select customer_id into CSID from customer where customer_name = name ; 
                               ^
CONTEXT:  invalid type name "customer_id into CSID from customer where customer_name "