I have tree tables:
table user_products
user_id | product_specific_id | order_no
1 | 1 | 1
1 | 2 | 1
1 | 3 | 2
table products_library
product_specific_id | product_id
1 | 3
2 | 3
3 | 1
table product_names
product_id | name
1 | prod1
2 | prod2
3 | prod3
Every product in the database does have unique product_id. But when user does order any product, he can modify it, so I created product_specific_id that I'm using in user_products, and table products_library where I can translate every unique product_specific_id to the base product_id.
Now every product_specific_id does have name of related product_id, that I do store in table product_names.
Now I need to display the name of every product_specific_id for specific user_idand order_no.
Expected result should look like this:
user_id | order_no | product_specific_id | name
1 | 1 | 1 | prod3
1 | 1 | 2 | prod3
I'm able to fit in two queries: first I'm selecting list of product_specific_id from user_products, and than I'm nesting SELECT like
SELECT name
FROM product_names
WHERE product_id IN (SELECT product_id
FROM products_library
WHERE product_specific_id IN (...)
But is it possible to fit everything it in one query? I have no idea how such thing could be achieved, if at all. Also, I'm not sure if nesting queries like this is good or not in the first place. Perhaps is it just fine to get it in two queries and nesting queries too much is bad idea?
You can try the below way using just JOIN
select user_id,order_no,u.product_specific_id,name
from user_products u join products_library p on u.product_specific_id=p.product_specific_id
join product_names pn on p.product_id=pn.product_id
where user_id=1 and order_no=1
Related
I have run into a problem that I'm sure is easy to achieve. I have a table for some merchandise. It holds all the information including the id for the manufacturer. The information about the manufacturer is in a separate table. When users are searching they have filter options. The one I'm having trouble with is filtering by manufacturer.
Products Table: cs_products
id | name | manufacturer_id
---------------------------
1 | mic | 3
2 | cable | 2
3 | speaker | 1
Manufacturer Table: cs_manufacturer
id | name
------------------
1 | JBL
2 | Rapco
3 | Shure
When the query is ran I need to ORDER BY cs_manufacturer.name:
mysql_query("SELECT * FROM cs_products ORDER BY cs_manufacturer.name")
What is the proper syntax for this?
SELECT * FROM cs_products JOIN cs_manufacturer
ON cs_product.manufacturer_id = cs_manufacturer.id
ORDER BY cs_manufacturer.name
You are missing your join.
SELECT * FROM cs_products
JOIN cs_manufacturer on cs_products.manufacturer_id = cs_manufacturer.id
ORDER BY cs_manufacturer.name
I have a orders table with the following columns:
-userid
-orderid (primary key)
-date
-name
-qty
So I would like to display in tables in a summary page all orders and group them under each userid. So it would be like
Userid: 0001
| Orderid | Name | QTY |
| 1001 | Item A | 10 |
| 1002 | Item B | 5 |
Userid: 0003
| Orderid | Name | QTY |
| 1003 | Item C | 6 |
| 1004 | Item C | 7 |
So far I've experimented and got:
display in a single table all the items ordered by userid
with a GROUP BY userid, I've managed to create as many tables as there are different userid
But I can't seem to combine the two into the desired results and would really appreciate some advice on what I am doing wrong.
Thanks in advance and I hope my explanation made sense!
I think you will need to do this in PHP
Query with
select * from orders order by userid, orderid
In PHP something like this psudo code
$this_user_id=0;
for (each order line)
{
get fields from db result;
if ($this_user_id!=$userid)
{
$this_user_id=$orderid// save change of userid flag
print user heading;
}
print order lines;
}
This is an example MYSQL result
+----+---+
| A | B |
+----+---+
| 1 | 1 |
| 1 | 2 |
| 2 | 3 |
| 2 | 4 |
| 3 | 5 |
+----+---+
I would like to run through every distinct in Column A and do something utilizing the values in Column B.
Let's say A has userids and B has foods. I would like to grab all the foods that user 1 likes and then shoot an email to 1, then grab all the foods that user 2 likes and email to her, and so forth. Would appreciate any suggestions.
If you want comma separated values, you can use GROUP_CONCAT
SELECT A, GROUP_CONCAT(DISTINCT B) foodList
FROM tableName
GROUP BY A
SQLFiddle Demo
Other Link
GROUP BY clause
Before I explain my problem, I will quickly go over how the table structure is:
Type: MySQL
Posts/topic Table:
int int** UNIX Time Int Int
--------------------------------------------------
| id | category | postdate | topic_id | is_topic |
--------------------------------------------------
| 1 | a | 12345678 | 1 | 1 |
--------------------------------------------------
| 2 | a | 12345678 | 1 | 0 |
--------------------------------------------------
| 3 | b | 12345678 | 3 | 1 |
--------------------------------------------------
| 4 | b | 12345678 | 3 | 0 |
--------------------------------------------------
| 5 | c | 12345678 | 5 | 1 |
--------------------------------------------------
| 6 | c | 12345678 | 5 | 0 |
--------------------------------------------------
**I'm using letters to make is easier to read the table
I am trying to retrieve the 4 newest rows for each category, and I am able to get the 1 newest from each category with GROUP BY, but I have no idea how to get multiple for each category.
I have tried something like this:
SELECT *
FROM posts p
WHERE NOT EXISTS
(
SELECT *
FROM posts
WHERE category = p.category
LIMIT 4
)
I also tried working with some of the other answers people supplied for some other answers here on SO, but I did not seem to be able to make them fit my purpose.
I am completely lost here, as mysql is not a strong side of mine when it comes to these more complex queries.
Any help or pointers in the right directions would really be appreciated!
Thanks!
UPDATE: Please note that the number of categories is not be static, and will change.
Something like this would probably do :
select * from
(select
#rank:=CASE WHEN #ranked <> category THEN 1 ELSE #rank+1 END as rank,
id,
category,
postdate,
topic_id,
is_topic
#ranked:=category
from
(select #rank := -1) a,
(select #ranked :=- -1) b,
(select * from posts order by category, postdate desc) c
) ranked_posts
where ranked_posts.rank <= 4
Basically what is happening here is that I am trying to create a "ranking" function present in other engines (MS SQL comes in mind).
The query goes through all the posts, ordered by category, postdate and adds a "ranking" number to every row resetting the rank when the category changes. Like:
rank | category
1 a
2 a
...
100 a
1 b
2 b
1 c
2 c
3 c
You do that inside a "sub query" to mimic a table then just select the rows that have rank <= 4, (the ones you need). If you need more or less you can adjust that number.
One thing to keep in mind is that the ordering is important or the ranks will get all screwed up. The categories have to be "grouped", hence the ORDER BY category and then the groups ordered by your criteria postdate desc.
I am new to the world of mysql and I'm having some trouble getting the data I need from a database.
The 2 tables I have are...
Results
ID | TITLE | LOTS OF OTHER DATA |
1 | res1 | |
2 | res2 | |
3 | res3 | |
4 | res4 | |
5 | res5 | |
Categories
ID | RESULT_ID | CATEGORY NAME |
1 | 1 | purchase |
2 | 1 | single_family |
3 | 1 | conventional |
4 | 2 | usda |
5 | 3 | somecategory |
I'm trying to create a query that will select results that belong to all of the categories provided in the query. For example a query for purchase & single_family & conventional in this example would return the first result in the results table.
Does that make sense? Is there a query that will do this or is this more of a problem with my database structure?
Thanks a lot!
Try something like this:
SELECT * FROM Results r
INNER JOIN Categories c on r.ID = c.RESULT_ID
WHERE c.name in ('purchase', 'single_family', 'conventional')
GROUP BY r.ID
HAVING COUNT(c.ID) = 3
The basic select with join will get you three rows only for result 1.
Edit: To make sure your code won't break if you change your database you should always select the fields you want explicitly: SELECT r.ID, .. FROM ..
So you're basically doing a simple join with all the category table for all categories where the category name is one of the names in the list. Try to run the 3 first lines manually to see the result you get.
Next you group by the result id. This means that you are aggregating all the rows sharing the same result id into one row. The last line means that we are filtering the aggregated columns that are aggregated by 3 rows. That means that you will only return results that have 3 matching categories.
So the only problem with this approach is if you have duplicate result_id, categoryname in your Categories table.