I have the following two tables.
nodes
attributes
nodes
id title
1 test
2 test2
attributes
id node_id title value
1 1 featured 1
2 1 age 13
3 2 featured 2
I would like query nodes with attribute title 'featured' along with its all attributes.
I tried to join, but I don't know how to query other attributes at the same time.
Is it possible to make a single query to do this?
You could use a subquery to get the ID's of all nodes with the attribute 'featured'. The outer query would be the JOIN to get the rest of the attributes.
Like:
SELECT n.*, a.*
FROM nodes n JOIN attributes a ON a.node_id=n.id
WHERE n.id IN
(SELECT DISTINCT no.id
FROM nodes no JOIN attributes at ON at.node_id=no.id AND at.title='featured')
I think this is a simple join
SELECT b.title as NodeTitle, a.title, a.value
FROM attributes a
INNER JOIN nodes b
ON a.node_id = b.id
Related
given these tables :
id_article | title
1 | super article
2 | another article
id_tag | title
1 | great
2 | awesome
id_relation | id_article | id_tag
1 | 1 | 1
2 | 1 | 2
3 | 2 | 1
I'd like to be able to select all articles that are "great" AND "awesome" (eventually, I'll probably have to implement OR too)
And basically, if I do a select on articles the relation table joining on id_article: of course, I cant join two different values of id_tag. Only lead I had with concatenating IDs to test as a string, but that seems so lame, there has to be a prettier solution.
Oh and if it matters, I use a MySQL server.
EDIT: for ByWaleed, the typical sql select that would surely fail that I cited in my original question:
SELECT
a.id_article,
a.title
FROM articles a, relations r
WHERE
r.id_article = a.id_article and r.id_tag = 1 and r.id_tag = 2
wouldnt work because r.id_tag cant obviously be 1 and 2 on the same line. I doubt w3schools has an article on that. My search on google didnt yield any result, probably because I searched with the wrong keyword.
If you do all the joins as normal, then aggregate the rows to one group by article, then you can assert that they must have at least two different tags.
(Having already filtered to great and/or awesome, that means they have both.)
SELECT
a.id_article,
a.title
FROM
articles a
INNER JOIN
relations r
ON r.id_article = a.id_article
INNER JOIN
tags t
ON t.id_tag = r.id_tag
WHERE
t.title IN ('great', 'awesome')
GROUP BY
a.id_article,
a.title
HAVING
COUNT(DISTINCT t.id_tag) = 2
(The DISTINCT is to avoid the possibility of one article having 'great' twice, for example.)
To do OR, you just remove the HAVING clause.
One approach is to aggregate by article, and then assert that the article both the "great" and "awesome" tags:
SELECT
a.id_article,
a.title
FROM articles a
INNER JOIN relations r
ON a.id_article = r.id_article
INNER JOIN tags t
ON r.id_tag = t.id_tag
WHERE
t.title IN ('great', 'awesome')
GROUP BY
a.id_article,
a.title
HAVING
MIN(t.title) <> MAX(t.title);
Demo
The logic here is that we first limit records, for each article, to only those of the two targets tags. Then we assert, in the HAVING clause, that both tags appear. I use a MIN/MAX trick here, because if the min and max differ, then it implies that there are two distinct tags.
Step 1: Use a temp table to get all articles with titles.
Step 2: If an article occurs multiple times in your temp table, that means it has great and awesome as titles.
Try:
CREATE TEMPORARY TABLE MyTempTable (
select t1.id_article, t2.title
from table1 t1
inner join table3 t3 on t3.id_article = t1.id_article
inner join table2 t2 on t2.id_tag = t3.id_tag
)
select m.id_article
from MyTempTable m
group by m.id_article
having count(*)>1
Edit: This solution assumes there are two possible tags, great and awesome. If more, please add a "where" clause to the select query for creating the temp table like where t2.title in ('great','awesome')
I have 3 tables: tags, products and relation table between them.
Relation table looks for example like this:
tagId | ProductId
1 | 1
2 | 1
2 | 9
The user can pick two options "All of these" or "One of these".
So if user picks All of these, it's means that the product must have exactly all of tags which the user chose.
So if user pick tags with id 1 and 2, it should select only product with id 1, because this product has exactly the same tags the user chose. (Another way is if the user picks the tag with id 2, it should select only product with id 9.)
So, the product has to have all tags which the user chose (no more, no less).
SQL that I already have for Any/One of these:
SELECT DISTINCT s.SKU
FROM SKUToEAN as s
LEFT JOIN ProductDetails as p ON s.ProductDetailID=p.id
JOIN ProductTagRelation as ptr ON (ptr.productId=p.id and ptr.tagId IN(Ids of selected tags))
Example behavior:
TagId = 1 it should select => None
TagId = 2 it should select => 9
TagId = 1,2 it should select = 1,9
So probably I need two queries. One for any/one of these ( I already have this one ) and the second for all of these.
With PHP I decide which query to use.
You can GROUP BY on the ProductID and use conditional aggregation based filtering inside the Having clause. MySQL automatically casts boolean values to 0/1 when using in numeric context. So, in order to have a specific tagID value available against a ProductID, its SUM(tagId = ..) should be 1.
All of these:
SELECT ptr.productId, s.SKU
FROM SKUToEAN AS s
LEFT JOIN ProductDetails AS p
ON p.id = s.ProductDetailID
JOIN ProductTagRelation AS ptr
ON ptr.productId = p.id
GROUP BY ptr.productId, s.SKU
HAVING SUM(ptr.tagID = 1) AND -- 1 should be there
SUM(ptr.tagID = 2) AND -- 2 should be there
NOT SUM(ptr.tagID NOT IN (1,2)) -- other than 1,2 should not be there
Is this you are looking for (for all condition)?
select product.id
from products
inner join <table> on products.id = <table>.productId
group by product.id
having group_concat(<table>.tagId order by <table>.tagId separator ',') = '1,2';
I have a table "Products" with a product name and id:
id | title
1 product 1
2 product 2
Each product can have a series of tags. Tags are identified in table "Attributes":
id | name | handle
1 Tag One tag-one
2 Tag Two tag-two
3 Tag Three tag-three
4 Tag Four tag-four
etc
The product to tag relationship is another table "Tags":
id | AttId | OwnerId
1 1 1
2 2 1
3 1 2
4 3 2
etc
Ok, so I am trying to select a set of products that all have at least one specific tag, and a possible selection of other tags. Here is what I am working with now:
SELECT products.id
FROM products
WHERE
EXISTS
(
SELECT 1
FROM Tags
INNER JOIN Attributes ON tags.AttId = Attributes.id
WHERE Attributes.handle = 'tag-one'
AND (
Attributes.handle = 'tag-two'
OR
Attributes.handle = 'tag-four'
)
AND products.id = Tags.OwnerId
)
If I remove the AND (OR) section, the query works. As above, it shows no errors, but also no results; How should I write this so I can get a set of products that have one tag for sure, AND have either/or other specified tags by the tag handle?
I like to approach this type of problem using group by and having -- because I find that this method works very well for expressing many different conditions. For your conditions:
select p.*
from products p join
tags t
on t.OwnerId = p.id join
attributes a
on t.attid = a.id
group by p.id
having sum(a.handle = 'tag-one') > 0 and
sum(a.handle in ('tag-two', 'tag-four')) > 0;
Each condition in the having clause counts the number of rows (for a product) that match a condition. The first says there is at least one row with 'tag-one' handle. The second says that there is at least one row with the other two handles.
I think if you perform two separate queries and take the intersection, that will give you what you want.
-- Get all the owner ids that have 'tag-one'
select OwnerId
from Tags t1
where AttId in
(
select id
from Attributes a1
where a1.handle = 'tag-one'
)
intersect
-- Get all the owner ids that have tag-two and tag-four
select OwnerId
from Tags t2
where AttId in
(
select id
from Attributes a2
where a2.handle in ('tag-two', 'tag-four')
)
;
I have a mysql table named "category". the basic structure looks like this-
------ -------- ------
cat_id cat_name parent
------ -------- ------
1 test1 NULL
2 test2 NULL
3 test3 2
4 test4 1
5 test5 3
now i want all the category data with parent category name (not only id) in a single query. is that possible? i could do it by using a second query (getting child's parent name) in a while loop and merging data as a whole. but is it possible to do this with a single query?
Join the table with itself, using the parent column to link to the cat_id of the parent.
SELECT c1.cat_id as childID, c1.cat_name ChildName, c2.cat_name as ParentName
from category c1
LEFT OUTER JOIN category c2
ON c1.parent = c2.cat_id
Be careful: since some elements have no parents (NULL), I put a LEFT
OUTER JOIN so those rows are displayed as well. If you don't want
that, use a JOIN instead of LEFT OUTER JOIN.
You can also show the lines, but display something else (empty or a
text or ...) instead of the NULL by using COALESCE.
You can consider the result as one (big) new table, so you can add WHERE clauses as you usually do, for example filtering on the parent name: WHERE c2.cat_name = 'test2'
Select p.cat_id, p.cat_name, c.cat_id, c.cat_name, c.parent
From category Left Join category On p.cat_id = c.parent
Where p.cat_name = 'name'
SELECT c1.category_name AS category, c2. category_name AS sub_category
FROM (
SELECT *
FROM category
) AS c1
INNER JOIN (
SELECT *
FROM category
) AS c2 ON c1.category_id = c2.category_id
I have a table "articles" with columns and data:
article_id title body
1 This is the title This is the body text
2 Another title Another body text
Another table "category" with columns and data:
category_id category
1 localnews
2 visible
3 first10
And a table "categories" with columns and data:
categories_id article_id category_id
1 1 1
2 1 2
3 1 3
4 2 1
5 2 3
I want to SELECT the row(s) WHERE categories.category_id = 1 AND =2 AND =3
I'm using:
SELECT articles.article_id, articles.title, articles.body,
categories.article_id, categories.category_id
FROM articles, categories
WHERE articles.article_id = categories.article_id
AND categories.article_id = 1
AND categories.article_id = 2
AND categories.article_id = 3
but it doesn't work. Obviously mySQL needs another syntax.
Can someone help?
Thanks
SELECT
Articles.article_id,
COUNT( Categories.article_id ) AS total
FROM CategoryArticles
LEFT JOIN Articles USING (article_id)
WHERE
CategoryArticles.category_id IN (1,2,3)
GROUP BY CategoryArticles.article_id
HAVING total = 3
I used a bit different names for table because in your example the distinction between category and categories is hard to notice.
An column of a row cannot be 1, 2 or 3 at the same time, which is what AND stipulates. Use OR in your WHERE condition. Better yet - for readability - you can use IN:
SELECT ...
WHERE `categories`.`article_id` IN(1,2,3)
In addition to the commonly used IN() and using a HAVING count, I would be interested in the performance difference by doing a multiple-join as follows...
SELECT STRAIGHT_JOIN
articles.article_id,
articles.title,
articles.body
FROM
categories c1
JOIN articles
on c1.article_id = articles.article_id
JOIN categories c2
on c1.article_id = c2.article_id
AND c2.category_id = 2
JOIN categories c3
on c1.article_id = c3.article_id
AND c3.category_id = 3
WHERE
c1.Category_ID = 1
Yes, this may look obscure, but lets think about it... by doing a join FIRST on the categories table where ONE of your specific categories -- THIS FIRST FROM instance of categories should be representative of whichever category would have the smallest granularity. Ex: Your categories of Local News, Visible and First 10. Local news would probably have the most entries, while Visible and First 10 would have even less... of those, which would have even the smallest number of records. Use THIS category as the where clause.
So, say you have 100,000 articles, and 90,000 are in local news, 45,000 in Visible, and 12,000 in First 10. By starting your query on only those in the 12,000, you are eliminating most of the data.
By then joining to the articles table, and categories AGAIN as alias C2 and C3 respectively based on the other conditions, if found, done, if not, its excluded.
Again, I'm wondering the performance impact. I would also have a compound index on the categories table on both (article_id, category_id)
The value cannot be all three values simultaneously, so you'd better use an IN clause in your WHERE to define which you want to return. Give you've already got a join condition there, you'd want to move that to an ON clause instead as well; ie:
SELECT articles.article_id, articles.title, articles.body, categories.article_id, categories.category_id
FROM articles
INNER JOIN categories ON articles.article_id = categories.article_id
WHERE categories.article_id IN ( 1, 2, 3 )
Of course, you can go to the next step and do:
SELECT articles.article_id, articles.title, articles.body, category.category
FROM articles
INNER JOIN categories ON articles.article_id = categories.article_id
INNER JOIN category ON categories.category_id = category.category_id
WHERE categories.article_id IN ( 1, 2, 3 )
If instead you wanted to show only articles that appear in all three categories, then you could take an approach like:
SELECT articles.article_id, articles.title, articles.body
FROM articles
INNER JOIN categories AS c1
ON articles.article_id = c1.article_id
AND c1.category_id = 1
INNER JOIN categories AS c2
ON articles.article_id = c2.article_id
AND c2.category_id = 2
INNER JOIN categories AS c3
ON articles.article_id = c3.article_id
AND c3.category_id = 3