Question

获得自动增量“计数器”的最佳方法是什么？取决于其他领域？

想象一下这张表

CUSTOMER - COUNTER
1 - 1
1 - 2
1 - 3
2 - 1
2 - 2

我为每个客户添加的每条记录都需要计数器增量1。

问候。

Answer 1

创建附加表以保存每个客户的计数器：

CREATE TABLE customer_counter
(
  customer_id  INTEGER NOT NULL,
  counter      INTEGER NOT NULL,

  PRIMARY KEY (customer_id)
)

使用以下程序获取给定客户的下一个柜台号码：

CREATE PROCEDURE get_customer_counter (customer_id INTEGER)
  RETURNS (counter INTEGER)
AS
BEGIN
  SELECT SUM(counter) FROM customer_counter
  WHERE customer_id = :customer_id
  INTO :counter;

  counter = COALESCE(:counter, 0);

  EXECUTE STATEMENT 
    'INSERT INTO customer_counter (customer_id, counter) ' ||
    'VALUES (' || :customer_id || ', 1)'
    WITH AUTONOMOUS TRANSACTION;
END

了解我们如何使用sum和插入delta值而不是更新单个记录。因此，我们可以防止死锁。

定期我们需要通过将delta记录合并为具有总值的记录来清除计数器表：

CREATE TRIGGER on_disconnect_database
  ACTIVE
  ON DISCONNECT
AS
  DECLARE VARIABLE sm          INTEGER;
  DECLARE VARIABLE cnt         INTEGER;
  DECLARE VARIABLE customer_id INTEGER;
BEGIN
  FOR
    SELECT customer_id, SUM(counter), COUNT(counter)
    FROM customer_counter
    GROUP BY customer_id
    INTO :customer_id, :sm, :cnt
  DO BEGIN
    IF (:cnt > 1) THEN
    BEGIN
      DELETE FROM customer_counter WHERE customer_id = :customer_id;
      INSERT INTO customer_counter (customer_id, counter)
        VALUES (:customer_id, :sm);
      WHEN ANY DO
      BEGIN
      END
    END
  END
END

Answer 2

很难真正告诉你对你所提供的内容的确切要求，但我认为你想要遍历每个X字段，它是Y子字段，将它用于计数器或其他任何东西。

<?php
$x = array("customer1","customer2","customer3");
$y = array("name","address","phone");

$counter;

foreach($x as $eachX):
    $counter  = 1;
    foreach($y as $eachY):
        //do stuff here
        $counter++;
    endforeach;
endforeach;
?>

Answer 3

我认为这个存储过程没问题！

create procedure New_Procedure
returns (
o_customer integer,
o_counter integer)
as

declare variable v_oldcostomer integer;
begin

for select customer
 from customers
 order by 1
 into o_customer
 do begin
 if (v_oldcostomer is null or (v_oldcostomer is not null and v_oldcostomer <> o_customer) ) then
    o_counter = 0;

 o_counter = o_counter + 1;
 v_oldcostomer = o_customer;
 suspend;
 end
end

自动增量依赖于其他领域

3 个答案: