SQL:在给定ID的where子句中查找下一行

Question

我products在MySQL数据库中有一个表.products看起来像这样:

id   name     din        strength active deleted
1    APA TEST 00246374   25       1      0
4    APA BOB  00246375   50       1      0
5    APA TIRE 00246888   50       1      0
7    APA ROT  00521414   100      1      0
9    APA APA  01142124   100      1      0
6    APA CODE 00121212   150      1      0
8    APA SERV 00011145   600      1      0

显然,我遗漏了几个对我的问题不重要的专栏.当我查询这个表时,我将按几个不同的列中的一个进行排序(用户界面允许单个用户更改排序列和顺序),我可能有一个搜索子句,在这种情况下我会做一个LIKE子句名称和DIN.

我想知道的是,鉴于排序信息和搜索信息,以及特定产品的ID(假设我搜索了004,返回了3个结果,我正在查看其中一个),我怎么能得到下一个和以前的产品？

我需要这样做,因为如果用户在搜索和排序结果后点击编辑/查看其中一个产品,他们希望能够循环浏览结果而无需转到上一页.

有没有一种好的有效方法在SQL中执行此操作,或者我最好使用PHP？任何想法也欢迎.

目前正在使用此SQL查询,如果我按strength列排序,则会遇到问题,因为存在重复值

SELECT T.*
FROM `wp_products` T
INNER JOIN `wp_products` curr on curr.id = 38
   AND ((T.strength = curr.strength and T.id < curr.id)
    OR (T.strength > curr.strength))
WHERE T.active = 1 AND T.deleted = 0 AND (T.name LIKE '%%' OR T.din LIKE '%%')
ORDER BY T.strength ASC, T.id ASC
LIMIT 1

我的PHP代码(使用WordPress)(旨在获取下一个项目)

    $sql = 'SELECT T.*
FROM `' . $wpdb->prefix . 'apsi_products` T
INNER JOIN `' . $wpdb->prefix . 'apsi_products` curr on curr.id = ' . $item->id . '
   AND ((T.' . $wpdb->escape( $query['orderby'] ) . ' = curr.' . $wpdb->escape( $query['orderby'] ) . ' and T.id > curr.id)
    OR (T.' . $wpdb->escape( $query['orderby'] ) . ' > curr.' . $wpdb->escape( $query['orderby'] ) . '))
WHERE T.active = 1 AND T.deleted = 0 AND (T.name LIKE \'%' . $query['where'] . '%\' OR T.din LIKE \'%' . $query['where'] . '%\')
ORDER BY T.' . $wpdb->escape( $query['orderby'] ) . ' ' . $query['order'] . ', T.id ASC
LIMIT 1;';

Answer 1

您需要引用当前记录,然后根据已排序的列逐步查找下一条记录.下面的示例假定它已排序

ORDER BY Active, DIN, NAME

第一:

SELECT *
FROM TABLE
WHERE NAME LIKE '%X%' AND DIN LIKE '%%'
ORDER BY Active, DIN, Name
LIMIT 1;

下一步:( 确保CURR.ID = 6用正确的括号将AND和OR 分开!)

SELECT *
FROM TABLE T
INNER JOIN TABLE CURR ON CURR.ID = 6 # the current ID being viewed
   AND ((T.Active = Curr.Active AND T.DIN = Curr.DIN AND T.NAME > Curr.Name)
     OR (T.Active = Curr.Active AND T.DIN > Curr.DIN)
     OR T.Active > Curr.Active)
WHERE T.NAME LIKE '%X%' AND T.DIN LIKE '%%'
ORDER BY T.Active, T.DIN, T.Name
LIMIT 1;

下面提供了一份工作样本

create table products
(ID int, SEED int, NAME varchar(20), DIN varchar(10), ACTIVE int, DELETED int);
insert products values
(1,  0,    'Product #1', '004812', 1,    0),
(2,  0,    'Product #2', '004942', 0,    0),
(3,  0,    'Product #3', '004966', 1,    0),
(4,  0,    'Product #4', '007437', 1,    1),
(5,  2,    'Product #2', '004944', 0,    0),
(6,  2,    'Product #2', '004944', 1,    0);

SELECT *
FROM products
WHERE active = 1 AND deleted = 0
ORDER BY din DESC, ID desc;

Output:
"ID";"SEED";"NAME";"DIN";"ACTIVE";"DELETED"
"3";"0";"Product #3";"004966";"1";"0"
"6";"2";"Product #2";"004944";"1";"0"
"1";"0";"Product #1";"004812";"1";"0"

如果current是ID = 6的行,则可以使用检索下一条记录

SELECT T.*
FROM products T
INNER JOIN products curr on curr.ID = 6
   AND ((T.din = curr.din and T.ID > curr.ID)
    OR (T.din < curr.din))
WHERE T.active = 1 AND T.deleted = 0
ORDER BY T.din DESC, T.ID ASC
LIMIT 1;