OK this is the data I am working with:
category_child_id category_parent_id
1 0
2 0
3 1
4 1
5 3
6 3
7 4
8 0
9 8
10 8
11 0
12 11
13 11
14 0
15 14
16 14
17 14
18 0
19 18
20 18
21 18
0 19
It's basically categories with sub categories etc etc.
If I
SELECT category_child_id FROM category_xref WHERE category_parent_id = 1
it returns 3 & 4 which is correct. However there are no products in this category only in the category below so the results I actually want are 5 & 6 as well. However this is not always the same so it does need to be a query.
So basically I need to run a query to get all connected(nested) categories from the table. I've tried many ways with failed results so any help would be great.
If you are using PostgreSQL you could have used "WITH RECURSIVE" but MySQL does not support dynamic, recursive queries. You have to do it with your accessing language (e.g. PHP, Java).
There you can iterate over your recordset and perform a query for each returned child row until no more child rows are returned.
As TRD says, there are extensions to SQL supporting recursive searching of self-joins (Oracle uses 'CONNECT BY') however not only are these not available in MySQL, they're also not the most efficient nor flexible solution.
Have a google for adjacency list model - I did and found this.
Related
Is there a good way in q to input somewhat large complicated nested dictionaries which represent/will be converted to json? I'm trying to control the echarts javascript library which basically just renders charts based on json config options. What I'm doing now is:
opt.title.text:"my chart"
opt.xAxis.data:til 100
opt.series.data:100?5
opt.series.type:`line
toClient[opt] /serializes and sends to browser
but is there an obvious way to get rid of the intermediate assignment? Is making a function to take key-path/value pairs and turn them into a dictionary the way to go or is there a better way to go about this?
Or is this something that should be avoided in q, and instead just manually set write q to set specific options and handle the json object map in the javascript client?
Not sure if this is really what you are looking for, but you can create the nested dictionary structure directly if that's what you're after?
q)`title`xAxis`series!(enlist[`text]!enlist"my chart";enlist[`data]!enlist til 100;`data`type!(100?5;`line))
title | (,`text)!,"my chart"
xAxis | (,`data)!,0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 ..
series| `data`type!(0 1 1 3 3 3 2 2 4 1 3 3 1 4 0 4 4 4 2 4 3 3 4 0 4 0 0 1 0..
Table
id name(varhcar)
2 15
3 15,23
4 1315,424
5 1512,2323
6 23,15,345
7 253,234,15
I need to find out those values which contains 15 which mean i need 2,3,6,7 not 4,5.
Above is sample data, in real time it can be any number.
Can anyone please help me?
If your database is small, consider using find_in_set function:
select * from your_table
where find_in_set('15',name);
Consider change the model to master-detail table to increase the speed if you have a big table.
This is the kind of relational model you could adopt to make this an easy problem to solve:
TABLE: records
id
2
3
4
5
6
7
TABLE: values
record_id value
2 15
3 15
3 23
4 1315
4 424
5 1512
5 2323
6 23
6 15
6 345
7 253
7 234
7 15
Then you can query:
SELECT DISTINCT id FROM records
INNER JOIN values ON records.id = values.record_id AND values.value = 15
This is the only way you can take good advantage of MySQL's query optimizer.
Not that it's impossible to do what you're trying to do, but it kind of misses the point.
If you're already storing data in this format, you should write a one-time migration to transfer it to this "normalized" format in the programming language of your choice, using something like Java's split or PHP's explode.
I am working on NGSim Traffic data, having 18 columns and 1180598 rows in a text file. I want to smooth the position data, in the column 'Local Y'. I know there are built-in functions for data smoothing in R but none of them seem to match with the formula I am required to apply. The data in text file looks something like this:
Index VehicleID Total_Frames Local Y
1 2 5 35.381
2 2 5 39.381
3 2 5 43.381
4 2 5 47.38
5 2 5 51.381
6 4 8 504.828
7 4 8 508.325
8 4 8 512.841
9 4 8 516.338
10 4 8 520.854
11 4 8 524.592
12 4 8 528.682
13 4 8 532.901
14 5 7 39.154
15 5 7 43.153
16 5 7 47.154
17 5 7 51.154
18 5 7 55.153
19 5 7 59.154
20 5 7 63.154
The above data columns are just example taken out of original file. Here you can see 3 vehicles, with vehicle IDs = 2, 4 and 5 but in fact there are 2169 vehicles with different IDS. The column Total_Frames tell us how many times vehicle Id of each vehicle is repeated in the first column, for example in the table above, vehicle ID 2 is repeated 5 times, hence '5' in Total_Frames column. Following is the formula I am required to apply to remove data noise (smoothing) from column 'Local Y':
Smoothed Position Value = (1/(Summation of [EXP^-abs(i-k)/delta] from k=i-D to i+D)) * ( (Summation of (Local Y) *[EXP^-abs(i-k)/delta] from k=i-D to i+D))
where,
i = index #
delta = 5
D = 15
I have tried using the built-in functions, which I know of, but they don't smooth the data as required. My question is: Is there any built-in function in R which can do the data smoothing in the way of given formula or which could take this formula as an argument? I need to apply the formula to every value in Local Y which has 15 values before and 15 values after them (i-D and i+D) for same vehicle Id. Can anyone give me any idea how to approach the problem? Thanks in advance.
You can place your formula in a function and then use the apply function of R to apply it to the elements in your "Local Y" column of the dataframe
I've got an issue where I've been presented data in this format from SQL, and have directly imported that into SSRS 2008.
I do have access to the stored procedure for this report, however I don't want to change it as a few other reports rely on it.
Project HoursSpent Cost
1 5 45
1 8 10
1 7 25
1 5 25
2 1 15
2 3 10
2 5 15
2 6 10
3 6 10
3 4 5
3 4 10
3 2 5
I've been struggling all morning to understand how/when I should be implementing the SUM() function with this.
I have tried already to SUM() the rows, but it still outputs the above result.
Should I be adding any extra groups?
Ideally, I need to have the following output:
Project HoursSpent Cost
1 25 105
2 15 40
3 16 30
EDIT: Here is my current structure:
"LineName" is a group for each project
You have to add a row group on "Project" since you want to sum up the data per each project.
I have array and table that I referenced some elements in array. Like my array
1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 16 17 18
19 20 21 22 23 24
And I have area like Start point s=9,X=2,Y=2,Row Count R=6
then I have boxes 9,10,11,15,16,17,21,22,23
Now I am trying to write some sql that check if 16 number in this area.I created some logic like if ((s<16<s+X) || (s+6<16<s+x+6) || (s+12<16<s+x+12) ) but should I write it in one sql query? I am using mySql.
This doesn't have anything to do with SQL, I don't think, but something like the following condition is probably what you want. Since your example has the same value of X and Y, and "Row Count" sounds more like "number of rows" than "number of items in a row," I may have gotten rows and columns backwards from what you want.
set #s=9, #x=2, #y=5, #R=6, #testval=16;
(#testval-1)/#R between (#s-1)/#R and (#s-1)/#R - #y - 1
and (#testval-1)%#R between (#s-1)%#R and (#s-1)%#R - #x - 1