Second highest column - sql

I have seen a similar question asked How to get second highest value among multiple columns in SQL ... however the solution won't work for Microsoft Access (Row_Number/Over Partition isn't valid in Access).
My Access query includes dozens of fields. I would like to create a new field/column that would return the second highest value of 10 specific columns that are included in the query, I will call this field "Cover". Something like this:
Product Bid1 Bid2 Bid3 Bid4 Cover
Watch 104 120 115 108 115
Shoe 65 78 79 76 18
Hat 20 22 19 20 20
I can do a really long SWITCH formula such as the following equivalent Excel formula:
IF( AND(Bid1> Bid2, Bid1 > Bid3, Bid1 > Bid4), Bid1,
AND(Bid2> Bid1, Bid2 > Bid3, Bid2 > Bid4), Bid2,
.....
But there must be a more efficient solution. A MAXIF equivalent would work perfectly if MS-Access Query had such a function.
Any ideas? Thank you in advance.

This would be easier if the data were laid out in a more normalized way. The clue is the numbered field names.
Your data is currently organized as a Pivot (known in Access as crosstab), but can easily be Unpivoted.
This data is much easier to work with if laid in a more normalized fashion which is this case would be:
Product Bid Amount
--------- ----- --------
Watch 1 104
Watch 2 120
Watch 3 115
Watch 4 108
Shoe 1 65
Shoe 2 78
Shoe 3 79
Shoe 4 76
Hat 1 20
Hat 2 22
Hat 3 19
Hat 4 20
This way querying becomes simpler.
It looks like you want the maximum of the bids, grouped by Product, so:
select Product, max(amount) as maxAmount
from myTable
group by product
Really, we shouldn't be storing text fields at all, so Product should be an ID number, with associated Product Names stored once in a separate table, instead of several times in the this one, like:
ProdID ProdName
-------- ----------
1 Watch
2 Shoe
3 Hat
... but that's another lesson.
Generally speaking repeating of anything should be avoided... that's pretty much the purpose of a database... but the links below will explain than I. :)
Quackit : Microsoft Access Tutorial
YouTube : DB Planning
Microsoft : Database Design Basics
Microsoft : Database Normalization Basics
Wikipedia : Database Normalization

Related

How to pivot the table containing each value in the output row in SQL

I can't resolve this issue. I tried to use PIVOT() function, I've read the documentation and tried to use that. Additionally, I tried to find the answer but didn't find.
The main problem is using PIVOT() function, that it has to include aggregation function, but I needn't it, I need only pivot the table without any aggregation.
The source table:
COUNTRY
LEVEL
NUMBER
Germany
High
22
Germany
Medium
5
Germany
Low
3
Italy
High
43
Italy
Medium
21
Italy
Low
8
Canada
High
9
Canada
Medium
3
Canada
Low
13
I'd like to get the output table looks like:
COUNTRY
High
Medium
Low
Germany
22
5
3
Italy
43
21
8
Canada
9
3
13
Can anybody help me?
How to do that without using aggregation function or using but the get all values. Cause, for example, if I use min() or max() I get the max and min value and the others cells would be empty.
why do you think that using min/max would leave empty cells? As there is only one value for each country/level combination then using min or max is effectively just picking that one value.
Obviously, if your source data had more than one record for each combination of country/level then you'd need to decide how to deal with it.
This SQL seems to work fine:
select *
from COUNTRY_INFO
pivot(max(NUMBER) for LEVEL in ('High', 'Medium', 'Low'))
as p
order by country;

Getting a specific number of results from a table

I'm new to mySQLi / SQL in general, so I wanted to ask a question regarding retrieving a certain amount of results in a specific way. Basically what I want to do is get all available information about the three fastest ships in the table below (using maxWarp field), but I don't know how to quite write that in SQL. I don't think it would just be right to say "SELECT * FROM Fleet WHERE maxWarp > 6"
**Table name: Fleet**
name class crew maxWarp
Enterprise Constitution 430 8
Excalibur Ambassador 260 9
Farragut Constitution 420 9
Prokofiev Andromeda 100 6
Select * from fleet order by maxwrap desc limit 3;

Is this SELECT and ORDER BY query the most efficient way I could have done it?

In my journey to learn SQL, I'm writing various queries on an old database of mine, but getting into more complex things, I want to make sure I'm not over engineering this. I have a table Agent, with different agents offering different prices for cities. Multiple agents can serve the same city, each with different prices. I wanted to run a query which would return the total cost of hiring all of the agents for any given city, ordered by the most expensive.
WITH orderedPrices AS (
SELECT SUM(agtFMPrice)
OVER (PARTITION BY agtCity)
AS IX FROM Agent)
SELECT IX
FROM orderedPrices
ORDER BY IX DESC
I found that doing it without the view returned by orderedPrices, it wouldn't order the prices (I assume because it's an aggregate function, or whatever they're called). Did I do this in the best way I could have, or could it be simplified?
Also, if you're feeling particularly bored, go ahead and give me a new assignment/query to do on this table. I could use the practice.
What you have written in English doesn't seem to quite match qhat you have written in SQL.
English:
- One record per City
- One field per record, showing the total cost of all associated agents
SQL:
- One record per Agent
- One field per record, showing the total cost of all agents in the same city
AgentID | agtCity | agtFMPrice
---------+---------+------------
1 | 1 | 10
2 | 1 | 20
3 | 2 | 30
4 | 2 | 10
5 | 2 | 25
Results of SQL version Results of English version
------------------------ ----------------------------
30 30
30 65
65
65
65
If you want the English version, I'd do this...
SELECT
agtCity,
SUM(agtFMPrice) AS IX
FROM
Agent
GROUP BY
agtCity
ORDER BY
SUM(agtFMPrice) DESC
To assist performance, the table could (should?) also have an Index on (agtCity)

Database design for a step by step wizard

I am designing a system containing logical steps with some actions associated (but the actions are not part of the question, but they are crucial for each step in the list)!
The ting is that I need to create a way to define all the logical steps in an ordered way, so that I can get the list by query, and also make modifications later on!
Anyone with some experience in this kind of database design?
I have been thinking of having a column named wizard_steps (or something similar), and then use priority to make the order, but for some reason i feel that this design at some point will fail (due to items with same priority, adding new items would then have to rearrange the rest of the items, and so forth)!
Another design I have been thinking about is the use of "next item" as a column in the wizard_step column, but I don't feel this is the correct step eighter!
So to summarize; I am trying to make a list (and the design should be open enought to support multiple lists) of elements where the order is crucial!
Any ideas on how the database should look like?
Thanks!
EDIT: I found this yii component I will check out: http://www.yiiframework.com/extension/simpleworkflow/
Might be a good solution!
If I get you well, your main concern is to create a schema that supports ordered lists and can provide easy insert/reordering of items.
The following table design:
id_list item_priority foreign_itemdef_id
1 1 245
1 2 32
1 3 45
2 1 156
2 2 248
2 3 127
coupled to a table with item definition will be easily queried but will be difficult to maintain, especially for insertions
That one:
id_list first_item_id
1 45
2 38
coupled to the linked list:
item_id next_item foreign_itemdef_id
45 381 56
381 NULL 59
38 39 89
39 42 78
42 NULL 45
Will be both difficult to query and update (you should update the linked list inside a transaction, otherwise your linked list can get corrupted).
I would prefer the first solution for simplicity.
Depending on your update frequency, you may consider using large increments between item_priority to help insertion:
id_list item_priority foreign_itemdef_id
1 1000 245
1 2000 32
1 3000 45
2 1000 156
2 2000 248
2 3000 127
1 2500 46 -- late insertion
1 2750 47 -- late insertion
EDIT:
Here's a query that will hopefully make room for an insertion: it increments priority of all rows above the argument
$query_make_room_for_new_item = "UPDATE item_priority_table SET item_priority = item_priority + 1 WHERE item_priority > ". $new_item_position_priority ." AND id_list = ".$id_list;
Then insert your item with priority $new_item_position_priority

Database design - alternatives for Entity Attribute Value (EAV)

see How to design a product table for many kinds of product where each product has many parameters for similar topic.
My question: i want to design a database, that will be used for a production facility of different types of products where each product has its own (number of) parameters.
because i want the serial numbers to be in one tabel for overview purposes i have a problem with these different paraeters .
One solution could be EAV, but it has its downsides, certainly because we have +- 5 products with every product +- 20.000 serial numbers (records). it looks a bit overkill to me...
I just don't know how one could design a database so that you have an attribute in a mastertable that says: 'hey, you could find details of this record in THAT detail-table".
'in a way that you qould easely query the results)
currenty i am using Visual Basic & Acces 2007. but i'm going to Visual Basic & MySQL.
thanks for your help.
Bob
I would go with something like this:
product [productid, title, price, datecreated, datemodified, etc]
attribute [attributeid, title]
productattribute [productid, attributeid, value, unit]
Example:
[product]
productid title price datecreated datemodified
1 LCD TV 99.95 2010-01-01 2010-01-01
2 Car 12356 2010-01-01 2010-01-02
3 B/W TV 12.95 1960-01-01 1960-01-01
[attribute]
attributeid title
10 Colors
11 Dimensions
12 Passengers
[productattribute]
productid attributeid value unit
1 10 16 million
1 11 32 inch
2 12 4 adults
3 10 2 colors
3 11 6 inch
It seems you probably need to learn more about the available design patterns when dealing with this sort of problem as there isn't a one-size-fits-all solution.
I recommend picking up a copy of Patterns of Enterprise Application Delvelopment to help you on your way. Sorry that I'm not able to answer your question directly (hopefully someone else here on SO can) but I think the answer given in the question you linked to is about as good as it gets.