访问数据库:TOP 子句和嵌套查询 + PHP 分页
Access DB: TOP clause and nested queries + PHP Paging
我正在开发一个 PHP 界面来显示来自两个不同数据库的一些结果:一个 MySQL 数据库 (.sql) 和一个 Access 数据库 (.mdb)。当我查询结果时,我让用户选择他想列出多少结果,这样我就可以通过一些 PHP 的乐趣来限制和分页它们。
这对于 MySQL 数据库来说是完美的,其中 LIMIT 子句以一种简洁的方式完成了所有事情。 Access DB 是另一回事:Access 没有 LIMIT 子句,所以我必须使用 TOP 子句。太糟糕了,这个让寻呼变得很痛苦。
我在 this question 的已接受答案中找到了一个很好的例子,但我遇到了问题。首先,让我向您展示几个片段查询:
查询 #1
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %';
查询#2
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Some_ID`;
查询 #1 仅按要求显示前 5 个结果。
太糟糕了,当我添加一个 ORDER BY 子句时,Query #2 返回所有满足我条件的结果。
像这样的 MySQL 查询不会发生同样的事情:
查询 #3
SELECT *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Some_ID`
LIMIT 0, 5;
那么,我的 Access 查询是否有问题?
为了完成我的问题,我的最终 Access 查询应该是这样的(我稍微修改了上述主题中提出的查询):
查询#4
SELECT *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE EXISTS (
SELECT TOP 5 * FROM (
SELECT TOP 10 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %')
ORDER BY `Table_1`.`Some_ID` DESC)
ORDER BY `Table_1`.`Some_ID` ASC;
我终于解决了我的问题。我会 post 我的查询,以防其他人遇到同样的问题。
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Timestamp`
IN (
SELECT TOP 5 `Table_1`.`Timestamp`
FROM (
SELECT TOP 10 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %'
AND `Table_2`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Timestamp` ASC)
ORDER BY `Table_1`.`Timestamp` DESC)
ORDER BY `Table_1`.`Timestamp` ASC;
只需尝试 "ASC" 和 "DESC" 即可获得您愿意返回的结果。
我正在开发一个 PHP 界面来显示来自两个不同数据库的一些结果:一个 MySQL 数据库 (.sql) 和一个 Access 数据库 (.mdb)。当我查询结果时,我让用户选择他想列出多少结果,这样我就可以通过一些 PHP 的乐趣来限制和分页它们。
这对于 MySQL 数据库来说是完美的,其中 LIMIT 子句以一种简洁的方式完成了所有事情。 Access DB 是另一回事:Access 没有 LIMIT 子句,所以我必须使用 TOP 子句。太糟糕了,这个让寻呼变得很痛苦。
我在 this question 的已接受答案中找到了一个很好的例子,但我遇到了问题。首先,让我向您展示几个片段查询:
查询 #1
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %';
查询#2
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Some_ID`;
查询 #1 仅按要求显示前 5 个结果。
太糟糕了,当我添加一个 ORDER BY 子句时,Query #2 返回所有满足我条件的结果。
像这样的 MySQL 查询不会发生同样的事情:
查询 #3
SELECT *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Some_ID`
LIMIT 0, 5;
那么,我的 Access 查询是否有问题?
为了完成我的问题,我的最终 Access 查询应该是这样的(我稍微修改了上述主题中提出的查询):
查询#4
SELECT *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE EXISTS (
SELECT TOP 5 * FROM (
SELECT TOP 10 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %' AND `Table_1`.`Timestamp` LIKE '2018/03/20 %')
ORDER BY `Table_1`.`Some_ID` DESC)
ORDER BY `Table_1`.`Some_ID` ASC;
我终于解决了我的问题。我会 post 我的查询,以防其他人遇到同样的问题。
SELECT TOP 5 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Timestamp`
IN (
SELECT TOP 5 `Table_1`.`Timestamp`
FROM (
SELECT TOP 10 *
FROM `Table_1` INNER JOIN `Table_2`
ON `Table_1`.`Some_ID` = `Table_2`.`Some_ID`
AND `Table_1`.`Timestamp` = `Table_2`.`Timestamp`
WHERE `Table_1`.`Some_ID` LIKE 'ID %'
AND `Table_2`.`Timestamp` LIKE '2018/03/20 %'
ORDER BY `Table_1`.`Timestamp` ASC)
ORDER BY `Table_1`.`Timestamp` DESC)
ORDER BY `Table_1`.`Timestamp` ASC;
只需尝试 "ASC" 和 "DESC" 即可获得您愿意返回的结果。