Question

我有单桌。

示例：

id | pattern | currencyid|pricelist_id| comment|cost|start_date
1  | ^.123.* |         30|           2| USA    |2.00|2014-03-20 20:12:00
2  | ^.123.* |         30|           2| USA    |3.00|2014-03-22 20:12:00
3  | ^.123.* |         30|           2| KENYA  |1.00|2014-03-24 20:12:00
4  | ^.123.* |         22|           2| CANADA |4.00|2014-03-26 20:12:00
5  | ^.123.* |         22|           2| CANADA |5.00|2014-03-29 20:12:00
6  | ^.123.* |         30|           2| USA    |6.00|2014-03-30 20:12:00
7  | ^.123.* |         30|           2| USA    |6.00|2014-04-12 20:12:00
8  | ^.123.* |         22|           2| INDIA  |8.00|2014-04-12 20:12:00

必需的OutPut：

id | pattern | currencyid|pricelist_id| comment|old_cost|old_start_date     |NEW_COST|NEW_start_date
3  | ^.123.* |         30|           2| KENYA  |1.00    |2014-03-24 20:12:00|6.00    |2014-03-30 20:12:00
4  | ^.123.* |         22|           2| CANADA |4.00    |2014-03-26 20:12:00|8.00    |2014-04-12 20:12:00

说明：

此处首先，模式总是相同或不同。

start_date＆gt; NOW（）和最接近当前日期时间然后它将被视为new_start_Date，其成本称为new_cost
start_date＆lt; NOW（）和最接近当前日期时间然后它将被视为old_date，其成本为old_cost
添加其他条件。

步骤：

我使用下面的查询获得所需的结果，这是一个非常漫长的过程。如果我有一些额外的地方，那么它只在下面的查询中添加，这是不合适的，需要在所有下面的查询中添加，并根据该结果给我结果

SELECT pattern, pricelist_id, currency_id
FROM "table"
WHERE pricelist_id=2
GROUP BY "pattern", "pricelist_id", "currency_id";

OUTPUT:
pattern | pricelist_id|currencyid
 ^.123.*|            2|30
 ^.123.*|            2|22

在php中使用foreach循环执行以下查询

SELECT "id" as new_id, "cost" as new_cost, "start_date" as new_start_date
FROM "table" 
WHERE "pricelist_id" = '2' 
  AND "start_date" > '2014-03-28 10:35:26' 
  AND "pattern" = '^.123.*' 
  AND "currencyid" = '30' 
ORDER BY "start_date" ASC
LIMIT 1

SELECT "id" as old_id, "cost" as old_cost, "start_date" as old_date, "comment"
FROM "table" 
WHERE "pricelist_id" = '2' 
  AND "start_date" <= '2014-03-28 10:35:26' 
  AND "pattern" = '^123.*' 
  AND "currencyid" = '30' 
ORDER BY "id" desc, "start_date" DESC 
LIMIT 1

但它需要很长时间才能获得100万条记录，所以如果可能的话请建议我查询哪些记录顺利进行。

是否可以通过单个PostgreSQL查询满足所有上述要求？

Answer 1

尝试使用WITH构造来获取计算数据：

with max_date as(select * from table where start_date < now() order by start_date desc limit 1),
min_date as(select * from table where start_date > now() order by start_date asc limit 1)
SELECT code, begin_time, (select code from max_date), (select code from min_date)
FROM table v 
where id in (
    (select id from max_date)
    union all
    (select id from min_date)
)

基于条件的postgresql查询

1 个答案: