If I have two tables:
Temp Snow
-------- -------------
School School Skip
-------- -------------
School 1 School 1 1
School 2 School 4 0
School 3 School 3 1
And I want to see if a 0 is present in the Skip column of table Snow, is it possible to just in the rows that contain the same School value? In this case, it would just search for a 0 in the School 3 and School 1 rows, because the School name matches up with the one from Temp.
Currently, I am using the following, but it's including every row:
SELECT Skip FROM Snow WHERE Skip = 0
You just need to join both tables. As you can see there are letters after the table names. They are called ALIASes (nickname) of the tables.
SELECT a.School
FROM Snow a
INNER JOIN Temp b
ON a.School = b.School
WHERE a.skip = 0
SQLFiddle Demo
Related
I could not find an answer by searching as I am not sure what exactly it would be called what I'm searching for.
Anyways, I have multiple tables in MySQL and am trying to "fill in" some of the final product.
myTable
id assigned_to location
1 2 3
2 2 3
3 3 3
myUsers
id name
1 John
2 David
3 Sally
myLocation
id name
1 SAT
2 DEN
3 AUS
Basically the end product should pull the "myTable" data and fill into a table (which I already know how to do) the name and location of each row/column so that it states something alongm the lines of
ID Assigned To Location
1 David SAT
Instead of
ID Assigned To Location
1 2 2
This should produce the expected result:
SELECT mt.id, mu.name, ml.name
FROM mytable mt JOINT myUsers mu ON mt.assigned_to = mu.id
JOIN myLocation ml ON mt.location = ml.id
I'm a new in Mysql and I have a complicated problem:
I have a table with "Shops" name in this table there is a ShopID column. The records look like this:
Shop_001
Shop_002...
Every "shopID" refer to a new table with this name, for example there is a table with Shop_0001 name. In this table there is "partnumber" column which mean the parts which are available in this shop.
I send a specific part number to sql server and I want to check all shops in the "Shops" table and return a rows in the "Shop_xxxx" tables which has this specific partnumber.
Unfortunately I have no idea how do I get start on this. Can anybody help me give some instruction or anything on this?
you're looking for a many to many relationship. so you just need 3 tables
1 table is the list of shops
1 table is the list of products
and 1 table is the list of which shops have which products. like this
table1
id|shops
------
1 shop1
2 shop2
3 shop3
table2
id|products
------
1 prod1
2 prod2
3 prod3
4 prod4
5 prod5
table3
id|shop_id|prod_id
-------------------
1 2 3
2 2 1
3 2 2
4 1 3
5 1 4
6 1 5
7 3 2
So for every time a product is added to a shop, an entry is added in table3. This will allow you to query by shops or by products, and you will only ever need 3 tables.
google querying many to many relationships for how to get the list of products for shop1 or the list of shops that have product4 etc.
i have a table of packages in which
Package_id name description
1 A abcdef
2 B ghijkl
3 C mnopq
and another table is user_comparisons
u_c_id user_id package_ids
1 1 1,2
2 2 2,1
3 1 1,3
i want to show packages with respect to user_comparisons against the users , how can i do that? if any one can help it will be appreciated, thanks in advance.
EDIT
I want to show packages like
user Comparisons # 1
Package 1 Package 2
Name description Name Description
User Comaprison # 2
Package 1 Package 3
Name Description Name Description
use FIND_IN_SET()
SELECT a.*, b.*
FROM user_comparison a
INNER JOIN packages b
ON FIND_IN_SET(b.Package_ID, a.package_IDs) > 0
SQLFiddle Demo
MySQL FIND_IN_SET
The current design of the database is bad. Consider normalizing the tables into three table design.
I have created a database and website that will be used by football managers to select their team etc. Once a match has been completed events will be stored in the match_players table. Such events are Goal, Yellow Card, Red Card etc. I have no problem getting this information into php from SQL db.
I need to add up how many times a Goal appears (a '1' is placed in the SQL table) and for what team so that a final score can be displayed. So, for example, if Team A has 1 goal and Team B has 2 then I need to display that. I am trying to count the amount of times that a Goal is registered in the table. Any help will be greatly appreciated.
You can use MYSQL SUM
select SUM(Goal) from match_players where Team="A"
Or you can get the same for all teams by
select Team,SUM(Goal) from match_players group by Team
Why don't you demand this sum to SQL directly?
SELECT SUM(goals)
FROM match_table
WHERE team = 'Barcellona'
This should be much faster also than elaborate all data at "php-level"
If you want this detail for all teams
SELECT team,SUM(goals)
FROM match_table
GROUP BY team
Well if you store a 1 each time a goal is scored, your table looks like this:
TeamID goal
1 1
2 1
1 1
3 1
2 1
2 1
1 1
So you just want a count of how many times a team appears in that table:
select TeamID, count(*) from table group by TeamID
Will give you
TeamID | count(*)
1 | 3
2 | 3
3 | 1
Im having a problem finding duplicate results in a mysql database (a cocktail recipe website). Here the setup:
Table 1: 'cocktail'
[cid,c_name] (cid = unique cocktail id, c_name = cocktail name)
Table 2: 'ingredients':
[iid,i_name] (iid = unique ingredient id, i_name = ingredient name)
Table 3: 'cocktail_ingredients' (the linking table)
[ciid,cid,iid] (ciid = unique row identifier, cid = cocktail cid, iid = ingredient iid)
So one cocktail can have multiple rows in the 'cocktail_ingredients' table (1 to many).
Setup is fine. The problem Im having now is finding if there are duplicate cocktails in my database.
For instance if the cocktail_ingredients table had these entries:
cid | iid
1 | 56
1 | 78
1 | 101
.
.
.
9 | 56
9 | 78
9 | 101
The cocktail is the same (for theoretical purposes here anyway).
If the 'cocktail_ingredients' table had one more row ...
9 | 103
Then it wouldn't be the same, as cocktail number 9 includes an extra ingredient.
So the mysql has to do 2 checks, firstly that the ingredient count is the same, and secondly that every ingredient id (iid) is the same for corresponding cocktails (cid).
Im stumped on this one, any help much appreciated. I'm thinking I might have to head down the PHP route as well to code in something more complex, but I'm struggling there as well so thought this would be a good place to stop and ask.
Thanks a ton
Nick
You may recall from a distant math class that the definition of set equality is that both A abd B are subsets of one another (non-strict) so just create a view or procedure that checks if every thin that is in A is also in B, then check the two cocktails are both subsets of one another. This is far from a complete answer, but it may be enough to get you going ;)
it will probably be easier to do the negation - find an ingredient in A that is not in B. none exist, then A must be a strict subset of B (assuming A and B can't both be empty)
Alternatively do a count of each ingredient in A, each ingredient ion B and each ingredient in A and B then if they are equal they are equivalent cocktails
CREATE VIEW ingredient_count AS
SELECT cid, count(*) as ingredients
FROM cocktail_ingredients
GROUP BY cid
CREATE VIEW shared_ingredients AS
SELECT c1.cid cid1, c2.cid cid2, count(*) as ingredients
FROM cocktail_ingredients as c1 INNER JOIN cocktail_ingredients as c2
ON (c1.cid != c2.cid AND c1.iid = c2.iid)
GROUP BY c1.cid,c2.cid
CREATE VIEW duplicates AS
SELECT cid1,cid2
FROM (ingredient_count AS ic1 INNER JOIN shared_ingredients
ON ic1.cid=cid1) INNER JOIN ingredient_count as ic2
ON ic2.cid=cid2
WHERE ic1.ingredients=ic2.ingredients
AND shared_ingredients=ic1.ingredients
Note this may be much faster in mysql with subselects with sensible where clauses rather than views, but this is easier to understand
You can impose such checking using TRIGGER.
But, yet there is a conceptual problem.
Say, you have two cocktails {1 | 56, 78, 101} and {9 | 56, 78, 101, 103} and also assume that you have implemented the check.
Now, you are inserting data for 1:
cid | iid
----------
1 | 56
Then, add rest two ingredients...
cid | iid
----------
1 | 56
1 | 78
1 | 101
Fine, now you start adding 9:
cid | iid
----------
1 | 56
1 | 78
1 | 101
9 | 56
You have three more ingredients, so continue adding them:
cid | iid
----------
1 | 56
1 | 78
1 | 101
9 | 56
9 | 78
Two more remaining (101,103)
But alas! You cannot add 101! If you try to add 101, then 9 would become identical to 1, which your trigger will prevent you from adding.
When a cocktail is subset of another, you have to add the subset later. I hope I could make you understand this.
You should not put any restriction in database. What I would do in my web application is:
In the cocktail entry/update interface, I would take user input (and not yet insert/update in DB)
When user clicks the save button (I would add a save button), check if the new/updated cocktail becomes copy of another (May be I would write a stored procedure, but it can be found using a select query only)
If the new/updated cocktail is not duplicate of another, insert/update database. If