脚本宝典收集整理的这篇文章主要介绍了MySql PHP从逗号分隔数据(标签)中选择不同值的计数，脚本宝典觉得挺不错的，现在分享给大家，也给大家做个参考。
如何从MySql中以逗号分隔值存储的数据中选择不同值的计数？我将使用PHP最终从MysqL输出数据.
那里有什么,每个帖子都有标签.所以最后,我正在尝试输出数据,就像stackoverflow使用它的标签一样,如下所示：
tag-name x 5
这就是表格中数据的样子(抱歉内容,但它是食谱的网站).
"postId" "tags" "category-code"
"1" "pho,pork" "1"
"2" "fried-rice,chicken" "1"
"3" "fried-rice,pork" "1"
"4" "chicken-calzone,chicken" "1"
"5" "fettuccine,chicken" "1"
"6" "spaghetti,chicken" "1"
"7" "spaghetti,chorizo" "1"
"8" "spaghetti,meat-balls" "1"
"9" "miso-soup" "1"
"10" "chanko-nabe" "1"
"11" "chicken-manchurian,chicken,manchurain" "1"
"12" "pork-manchurian,pork,manchurain" "1"
"13" "sweet-and-sour-pork,pork" "1"
"14" "peking-duck,duck" "1"
产量
chicken 5 // occurs 5 time in the data above
pork 4 // occurs 4 time in the data above
spaghetti 3 // an so on
fried-rice 2
manchurian 2
pho 1
chicken-calzone 1
fettuccine 1
chorizo 1
meat-balls 1
miso-soup 1
chanko-nabe 1
chicken-manchurian 1
pork-manchurian 1
sweet-n-sour-pork 1
peking-duck 1
duck 1
我试图在那里选择所有不同值的计数,但由于它是逗号分隔的数据,似乎没有办法做到这一点. select distinct不起作用.
你能想到一个很好的方式在MysqL或使用PHP来获得输出,就像我做的那样？
解决方法:
解
我真的不知道如何将逗号分隔值的@R_403_2278@转换为行列表而不创建包含数字的表,因为您可能有逗号分隔值的数字.如果你可以创建这个表,这是我的答案：
SELECT
SUBSTRING_INDEX(SUBSTRING_INDEX(all_tags, ',', num), ',', -1) AS one_tag,
COUNT(*) AS cnt
FROM (
SELECT
GROUP_CONCAT(tags separator ',') AS all_tags,
LENGTH(GROUP_CONCAT(tags SEPARATOR ',')) - LENGTH(REPLACE(GROUP_CONCAT(tags SEPARATOR ','), ',', '')) + 1 AS count_tags
FROM test
) t
JOIN numbers n
ON n.num <= t.count_tags
GROUP BY one_tag
ORDER BY cnt DESC;
返回：
+---------------------+-----+
| one_tag | cnt |
+---------------------+-----+
| chicken | 5 |
| pork | 4 |
| spaghetti | 3 |
| fried-rice | 2 |
| manchurain | 2 |
| pho | 1 |
| chicken-calzone | 1 |
| fettuccine | 1 |
| chorizo | 1 |
| meat-balls | 1 |
| miso-soup | 1 |
| chanko-nabe | 1 |
| chicken-manchurian | 1 |
| pork-manchurian | 1 |
| sweet-and-sour-pork | 1 |
| peking-duck | 1 |
| duck | 1 |
+---------------------+-----+
17 rows in set (0.01 sec)
释
脚本
>我们使用逗号连接所有标签,只创建一个标签列表,而不是每行一个
>我们计算列表中有多少个标签
>我们发现如何在此列表中获取一个值
>我们发现如何将所有值作为不同的行
>我们计算按其值分组的标签
上下文
让我们构建你的架构：
CREATE TABLE test (
id INT PRIMARY KEY,
tags VARCHAR(255)
);
INSERT INTO test VALUES
("1", "pho,pork"),
("2", "fried-rice,chicken"),
("3", "fried-rice,pork"),
("4", "chicken-calzone,chicken"),
("5", "fettuccine,chicken"),
("6", "spaghetti,chicken"),
("7", "spaghetti,chorizo"),
("8", "spaghetti,meat-balls"),
("9", "miso-soup"),
("10", "chanko-nabe"),
("11", "chicken-manchurian,chicken,manchurain"),
("12", "pork-manchurian,pork,manchurain"),
("13", "sweet-and-sour-pork,pork"),
("14", "peking-duck,duck");
连接所有标签列表
我们将在一行中使用所有标签,因此我们使用GROUP_CONCAT来完成工作：
SELECT GROUP_CONCAT(tags SEPARATOR ',') FROM test;
返回以逗号分隔的所有标记：
为了计算所有标签,我们得到完整标签列表的长度,并且在替换之后,我们删除完整标签列表的长度.我们加1,因为分隔符在两个值之间.
SELECT LENGTH(GROUP_CONCAT(tags SEPARATOR ',')) - LENGTH(REPLACE(GROUP_CONCAT(tags SEPARATOR ','), ',', '')) + 1 AS count_tags
FROM test;
返回：
+------------+
| count_tags |
+------------+
| 28 |
+------------+
1 row in set (0.00 sec)
-- returns the string until the 2nd delimiter\'s occurrence from left to right: a,b
SELECT SUBSTRING_INDEX('a,b,c', ',', 2);
-- return the string until the 1st delimiter, from right to left: c
SELECT SUBSTRING_INDEX('a,b,c', ',', -1);
-- we need both to get: b (with 2 being the tag number)
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX('a,b,c', ',', 2), ',', -1);
有了这样的逻辑,为了在列表中获得第3个标记,我们使用：
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(GROUP_CONCAT(tags SEPARATOR ','), ',', 3), ',', -1)
FROM test;
返回：
+-------------------------------------------------------------------------------------+
| SUBSTRING_INDEX(SUBSTRING_INDEX(GROUP_CONCAT(tags SEPARATOR ','), ',', 3), ',', -1) |
+-------------------------------------------------------------------------------------+
| fried-rice |
+-------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
将所有值作为不同的行
我的想法有点棘手：
>我知道我们可以通过连接表来创建行
>我需要使用上面的请求在列表中获取第N个标记
因此,我们将创建一个表,其中包含从1到您列表中可能包含的最大标记数的所有数字.如果您可以拥有1M值,请创建1到1,000,000的1M条目.对于100个标签,这将是：
CREATE TABLE numbers (
num INT PRIMARY KEY
);
INSERT INTO numbers VALUES
( 1 ), ( 2 ), ( 3 ), ( 4 ), ( 5 ), ( 6 ), ( 7 ), ( 8 ), ( 9 ), ( 10 ),
( 11 ), ( 12 ), ( 13 ), ( 14 ), ( 15 ), ( 16 ), ( 17 ), ( 18 ), ( 19 ), ( 20 ),
( 21 ), ( 22 ), ( 23 ), ( 24 ), ( 25 ), ( 26 ), ( 27 ), ( 28 ), ( 29 ), ( 30 ),
( 31 ), ( 32 ), ( 33 ), ( 34 ), ( 35 ), ( 36 ), ( 37 ), ( 38 ), ( 39 ), ( 40 ),
( 41 ), ( 42 ), ( 43 ), ( 44 ), ( 45 ), ( 46 ), ( 47 ), ( 48 ), ( 49 ), ( 50 ),
( 51 ), ( 52 ), ( 53 ), ( 54 ), ( 55 ), ( 56 ), ( 57 ), ( 58 ), ( 59 ), ( 60 ),
( 61 ), ( 62 ), ( 63 ), ( 64 ), ( 65 ), ( 66 ), ( 67 ), ( 68 ), ( 69 ), ( 70 ),
( 71 ), ( 72 ), ( 73 ), ( 74 ), ( 75 ), ( 76 ), ( 77 ), ( 78 ), ( 79 ), ( 80 ),
( 81 ), ( 82 ), ( 83 ), ( 84 ), ( 85 ), ( 86 ), ( 87 ), ( 88 ), ( 89 ), ( 90 ),
( 91 ), ( 92 ), ( 93 ), ( 94 ), ( 95 ), ( 96 ), ( 97 ), ( 98 ), ( 99 ), ( 100 );
SELECT n.num, SUBSTRING_INDEX(SUBSTRING_INDEX(all_tags, ',', num), ',', -1) as one_tag
FROM (
SELECT
GROUP_CONCAT(tags SEPARATOR ',') AS all_tags,
LENGTH(GROUP_CONCAT(tags SEPARATOR ',')) - LENGTH(REPLACE(GROUP_CONCAT(tags SEPARATOR ','), ',', '')) + 1 AS count_tags
FROM test
) t
JOIN numbers n
ON n.num <= t.count_tags
返回：
+-----+---------------------+
| num | one_tag |
+-----+---------------------+
| 1 | pho |
| 2 | pork |
| 3 | fried-rice |
| 4 | chicken |
| 5 | fried-rice |
| 6 | pork |
| 7 | chicken-calzone |
| 8 | chicken |
| 9 | fettuccine |
| 10 | chicken |
| 11 | spaghetti |
| 12 | chicken |
| 13 | spaghetti |
| 14 | chorizo |
| 15 | spaghetti |
| 16 | meat-balls |
| 17 | miso-soup |
| 18 | chanko-nabe |
| 19 | chicken-manchurian |
| 20 | chicken |
| 21 | manchurain |
| 22 | pork-manchurian |
| 23 | pork |
| 24 | manchurain |
| 25 | sweet-and-sour-pork |
| 26 | pork |
| 27 | peking-duck |
| 28 | duck |
+-----+---------------------+
28 rows in set (0.01 sec)
只要我们现在有经典行,我们就可以轻松计算每个标记的出现次数.
请参阅top of this answer以查看请求.
以上是脚本宝典为你收集整理的MySql PHP从逗号分隔数据(标签)中选择不同值的计数全部内容，希望文章能够帮你解决MySql PHP从逗号分隔数据(标签)中选择不同值的计数所遇到的问题。
本图文内容来源于网友网络收集整理提供，作为学习参考使用，版权属于原作者。
如您有任何意见或建议可联系处理。小编QQ：384754419，请注明来意。