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一、 Oracle

CREATE OR REPLACE PROCEDURE p_name (
   p_in_param1 IN data_type1,
   p_out_param1 OUT data_type2,
   p_inout_param1 IN OUT data_type3
) AS
   -- 存储过程语句
BEGIN
   -- 存储过程执行体
END;
/

二、MySQL

CREATE PROCEDURE p_name (
   IN p_in_param1 data_type1,
   OUT p_out_param1 data_type2,
   INOUT p_inout_param1 data_type3
)
BEGIN
   -- 存储过程执行体
END;

三、SQL Server

CREATE PROCEDURE p_name (
   @p_in_param1 data_type1,
   @p_out_param1 data_type2 OUT,
   @p_inout_param1 data_type3 INOUT
) AS
BEGIN
   -- 存储过程执行体
END;

四、PostgreSQL

CREATE OR REPLACE FUNCTION p_name (
   p_in_param1 data_type1,
   OUT p_out_param1 data_type2,
   INOUT p_inout_param1 data_type3
) AS $$
BEGIN
   -- 存储过程执行体
END;
$$ LANGUAGE 'plpgsql';

五、例子

Oracle

CREATE TABLE orders (
   order_id INT PRIMARY KEY,
   customer_id INT,
   order_date DATE,
   total_price DECIMAL(10, 2)
);

CREATE TABLE order_items (
   order_id INT,
   product_id INT,
   quantity INT,
   price DECIMAL(10, 2)
);

INSERT INTO orders VALUES (1, 1, '2022-01-01', 1000);
INSERT INTO orders VALUES (2, 1, '2022-01-02', 2000);
INSERT INTO orders VALUES (3, 2, '2022-01-03', 3000);

INSERT INTO order_items VALUES (1, 1, 10, 100);
INSERT INTO order_items VALUES (1, 2, 20, 200);
INSERT INTO order_items VALUES (2, 1, 30, 100);
INSERT INTO order_items VALUES (2, 2, 40, 200);
INSERT INTO order_items VALUES (3, 1, 50, 100);
INSERT INTO order_items VALUES (3, 2, 60, 200);

CREATE OR REPLACE PROCEDURE get_order_summary (
   p_customer_id IN orders.customer_id%TYPE
) AS
   v_total_orders orders.total_price%TYPE;
   v_total_items NUMBER;
BEGIN
   SELECT SUM(total_price)
   INTO v_total_orders
   FROM orders
   WHERE customer_id = p_customer_id;

   SELECT SUM(quantity)
   INTO v_total_items
   FROM order_items
   WHERE order_id IN (
      SELECT order_id FROM orders WHERE customer_id = p_customer_id
   );

   DBMS_OUTPUT.PUT_LINE('Total Orders: ' || v_total_orders);
   DBMS_OUTPUT.PUT_LINE('Total Items: ' || v_total_items);
END;
/

EXECUTE get_order_summary(1);

MySQL

CREATE TABLE orders (
   order_id INT PRIMARY KEY,
   customer_id INT,
   order_date DATE,
   total_price DECIMAL(10, 2)
);

CREATE TABLE order_items (
   order_id INT,
   product_id INT,
   quantity INT,
   price DECIMAL(10, 2)
);

INSERT INTO orders VALUES (1, 1, '2022-01-01', 1000);
INSERT INTO orders VALUES (2, 1, '2022-01-02', 2000);
INSERT INTO orders VALUES (3, 2, '2022-01-03', 3000);

INSERT INTO order_items VALUES (1, 1, 10, 100);
INSERT INTO order_items VALUES (1, 2, 20, 200);
INSERT INTO order_items VALUES (2, 1, 30, 100);
INSERT INTO order_items VALUES (2, 2, 40, 200);
INSERT INTO order_items VALUES (3, 1, 50, 100);
INSERT INTO order_items VALUES (3, 2, 60, 200);

DELIMITER //

CREATE PROCEDURE get_order_summary (
   IN p_customer_id INT
)
BEGIN
   DECLARE v_total_orders DECIMAL(10, 2);
   DECLARE v_total_items INT;

   SELECT SUM(total_price) INTO v_total_orders
   FROM orders
   WHERE customer_id = p_customer_id;

   SELECT SUM(quantity) INTO v_total_items
   FROM order_items
   WHERE order_id IN (
      SELECT order_id FROM orders WHERE customer_id = p_customer_id
   );

   SELECT CONCAT('Total Orders: ', v_total_orders) AS output1,
          CONCAT('Total Items: ', v_total_items) AS output2;
END//

DELIMITER ;

CALL get_order_summary(1);

SQL Server

CREATE TABLE orders (
   order_id INT PRIMARY KEY,
   customer_id INT,
   order_date DATE,
   total_price DECIMAL(10, 2)
);

CREATE TABLE order_items (
   order_id INT,
   product_id INT,
   quantity INT,
   price DECIMAL(10, 2)
);

INSERT INTO orders VALUES (1, 1, '2022-01-01', 1000);
INSERT INTO orders VALUES (2, 1, '2022-01-02', 2000);
INSERT INTO orders VALUES (3, 2, '2022-01-03', 3000);

INSERT INTO order_items VALUES (1, 1, 10, 100);
INSERT INTO order_items VALUES (1, 2, 20, 200);
INSERT INTO order_items VALUES (2, 1, 30, 100);
INSERT INTO order_items VALUES (2, 2, 40, 200);
INSERT INTO order_items VALUES (3, 1, 50, 100);
INSERT INTO order_items VALUES (3, 2, 60, 200);

CREATE PROCEDURE get_order_summary (
   @p_customer_id INT
) AS
BEGIN
   SELECT SUM(total_price) AS total_orders,
          SUM(quantity) AS total_items
   FROM orders
   JOIN order_items ON orders.order_id = order_items.order_id
   WHERE customer_id = @p_customer_id;
END;

EXECUTE get_order_summary @p_customer_id = 1;

PostgreSQL

CREATE TABLE orders (
   order_id SERIAL PRIMARY KEY,
   customer_id INT,
   order_date DATE,
   total_price DECIMAL(10, 2)
);

CREATE TABLE order_items (
   order_id INT,
   product_id INT,
   quantity INT,
   price DECIMAL(10, 2)
);

INSERT INTO orders VALUES (1, 1, '2022-01-01', 1000);
INSERT INTO orders VALUES (2, 1, '2022-01-02', 2000);
INSERT INTO orders VALUES (3, 2, '2022-01-03', 3000);

INSERT INTO order_items VALUES (1, 1, 10, 100);
INSERT INTO order_items VALUES (1, 2, 20, 200);
INSERT INTO order_items VALUES (2, 1, 30, 100);
INSERT INTO order_items VALUES (2, 2, 40, 200);
INSERT INTO order_items VALUES (3, 1, 50, 100);
INSERT INTO order_items VALUES (3, 2, 60, 200);

CREATE OR REPLACE FUNCTION get_order_summary (
   p_customer_id INT
)
RETURNS TABLE (
   total_orders DECIMAL(10, 2),
   total_items INT
) AS $$
BEGIN
   RETURN QUERY SELECT SUM(total_price), SUM(quantity)
   FROM orders
   JOIN order_items ON orders.order_id = order_items.order_id
   WHERE customer_id = p_customer_id;
END;
$$ LANGUAGE 'plpgsql';

SELECT * FROM get_order_summary(1);

存储过程调用后的结果

Oracle

执行 EXECUTE get_order_summary(1); 后，控制台输出：

Total Orders: 3000
Total Items: 100

MySQL

执行 CALL get_order_summary(1); 后，结果为：

SQL Server

执行 EXECUTE get_order_summary @p_customer_id = 1; 后，结果为：

PostgreSQL

执行 SELECT * FROM get_order_summary(1); 后，结果为：

以上的例子都是基于多表关联查询的，通过存储过程可以将查询语句封装成一个可重用的模块，提高了代码的可维护性和可复用性。