Question

作为最后的手段，写这篇文章几乎已经烧掉......

大家好，我希望得到一些我需要创建的第一个功能的帮助。根据我的阅读，我理解您只需要将函数页眉和页脚添加到任何SQL命令集以创建函数。

我有一个视图，我已经创建了哪个工作正常...这是它的代码

CREATE VIEW invoice_v AS 
SELECT customer.firstname, lastname, customer_addresses.address, orders.order_id, order_date, order_total, order_details.product_id, quantity, unitprice, product.product_name
FROM customer, customer_addresses, orders, order_details, product
WHERE customer.customer_id = customer_addresses.customer_id 
AND customer.customer_id = orders.customer_id
AND orders.order_id = order_details.order_id
AND product.product_id = order_details.product_id;

SELECT firstname, lastname, address, order_id, order_date, product_id, product_name, quantity, unitprice, order_total
FROM invoice_v
WHERE order_id = 02;

它的作用是为Invoice创建一个视图，其中包含order_id 2的所有详细信息。

我需要用函数做类似的事情。我不知道如何做到这一点。

这就是我试图做的......但是失败了，我很抱歉，如果这看起来非常愚蠢，但我是新手......

CREATE FUNCTION invoiceforprint() RETURNS name AS '

SELECT customer.firstname, lastname, customer_addresses.address, orders.order_id, order_date, order_total, order_details.product_id, quantity, unitprice, product.product_name
FROM customer, customer_addresses, orders, order_details, product
WHERE customer.customer_id = customer_addresses.customer_id 
AND customer.customer_id = orders.customer_id
AND orders.order_id = order_details.order_id
AND product.product_id = order_details.product_id;

' LANGUAGE SQL;

上面的代码给了我这个错误

ERROR:  return type mismatch in function declared to return name
DETAIL:  Final statement must return exactly one column.
CONTEXT:  SQL function "invoiceforprint"

我甚至不知道我应该为RETURN使用什么参数。任何有关此事的帮助，将不胜感激。

Answer 1

抱歉不要靠近postgres DB，所以这是未经测试的。

你所追求的是一个表函数，这里有一个例子http://www.postgresql.org/docs/9.1/static/sql-createfunction.html

CREATE FUNCTION invoiceforprint() RETURNS TABLE(firstname text
       , lastname text
       , address text
       , order_id int
       , order_date date 
       , order_total numeric
       , product_id int
       , quantity numeric
       , unitprice numeric,
       , product_name text ) AS 
$$
SELECT customer.firstname
       , lastname
       , customer_addresses.address
       , orders.order_id
       , order_date
       , order_total
       , order_details.product_id
       , quantity
       , unitprice 
       , product.product_name
FROM customer, customer_addresses, orders, order_details, product
WHERE customer.customer_id = customer_addresses.customer_id 
AND customer.customer_id = orders.customer_id
AND orders.order_id = order_details.order_id
AND product.product_id = order_details.product_id;
$$ LANGUAGE SQL;

Postgresql函数创建ERROR：声明返回名称的函数返回类型不匹配

1 个答案: