I'm way out of my league here...
I have a mapping table (table1) to assign particular values (value) to a whole number (map_nu). My second table (table2), is a collection of averages (avg) for each user (user_id).
(I couldn't figure out how to properly make a markdown table, please feel free to edit!)
table1: table2:
(value)(Map_nu) (user_id)(avg)
---- -----
1 1 1 1.111
1.045 2 2 1.2
1.09 3 3 1.33333
1.135 4 4 1
1.18 5 5 1.389
1.225 6 6 1.42
1.27 7 7 1.07
1.315 8
1.36 9
1.405 10
The value Map_nu is a special number that each user gets assigned according to their average. I need to find a way to match the averages from table2 to the closest value in table1. I only need to match to the 2 digit past the decimal, so I've added the Truncated function
SELECT table2.user_id, map_nu
FROM `table1`
JOIN table2 ON TRUNCATE(table1.value,2)=TRUNCATE(table2.avg,2)
I still miss the values that don't match the averages exactly. Is there a way to pick the nearest truncated value or even to round to the second decimal? Rounding up/down wont matter as long as its applied to all values the same.
I am trying to have the following result (if rounded up):
(user_id)(Map_nu)
----
1 4
2 6
3 6
4 1
5 10
6 11
7 3
Thanks!
i think you might have to do this in 2 separate queries. there is no 'nearest' operator in sql, so you can either calculate it in your software, or you could use
select map_nu from table1 ORDER BY abs(value - $avg) LIMIT 1
inside a loop. however, that cannot be used as a join function as it requires the ORDER and LIMIT which are not valid as joins.
another way of looking at it is it seems that your map_nu and value are deterministic in relation to each other - value = 1 + ((map_nu - 1) * 0.045) - so maybe you could make use of that fact and calculate an integer based on that equation? assuming that relationship holds true for all values of map_nu.
This is an awkward database design. What is the data representing and what are you trying to solve? There might be a better way.
Maybe do something like...
SELECT a.user_id, b.map_nu, abs(a.avg - b.value)
FROM
table2 a
join table1 b
left join table1 c on abs(a.avg - b.value) > abs(a.avg - c.value)
where c.value is null
order by a.user_id
Doesn't actually produce the same output as the one you were expecting for (doesn't do any rounding). Though you should be able to tweak it from there. Above query will produce the output below (w/ data you've provided):
user_id map_nu abs(a.avg - b.value)
------- ------ --------------------
1 3 0.0209999999999999
2 5 0.02
3 8 0.01833
4 1 0
5 10 0.016
6 10 0.0149999999999999
7 3 0.02
Beware though if you're dealing with large tables. Evaluate the explain of the above query if it'll be practical to run it within MySQL or if better to be done outside it.
Note 2: Will produce duplicate rows if there are avg values that are equi-distant to value values within table1 (Ex. if value for map_nu's 11 and 12 are 2 and 3 and someone get's an avg of 2.5). Your question doesn't really specify what to do for that so you might want to take that into account.
Its taking a little extra work, but I figure the easiest way to get my results will be to map all values to the second decimal place in table1:
1 1
1.01 1
1.02 1
1.03 1
1.04 1
1.05 2
1.06 2
1.07 2
1.08 2
1.09 3
1.1 3
1.11 3
1.12 3
1.13 3
1.14 4
...
Thanks for the suggestions! Sorry I couldn't present the question more clear.
Related
Sounds simple but I couldn't find the solution for it.
I have a table with 3 columns. Account, Amount, Date.
I want to get all entries except the ones of one specific account with negative amount. But I still want to get the entries of this account if amount value is positive.
So with this query I'm also not getting the entries from account1 with a positive amount.
select * from table where (account!='account1' AND amount<='0') AND date='2020-05-01'
You can do this using WHERE NOT in your statement.
Example schema:
Account Amount Date
=====================================
1 Ben 200 2020-10-10
2 Frank 200 2020-10-10
3 Ben -300 2020-10-12
4 Ben 10 2020-10-16
5 Mary 2000 2020-10-16
6 Frank -200 2020-10-18
7 Ben -10 2020-10-18
8 Ben 0 2020-10-20
Now if you build your query like this
SELECT * FROM t1 WHERE NOT (account='Ben' AND amount<0);
you should get what you want (all records except the 3rd and 7th).
Edit: if you really only want to exclude records with negative amounts, you need to do < rather than <= as you did in your example above. Depends on whether you want row 8 to be included in the result or not.
here are records and we want move id #1 between #3 & #4
id title sort
1 a 1
2 b 2
3 c 3
4 d 4
5 e 5
6 f 6
method one :
get #3 sort number and plus 1 to it and update #1 sort with that so we have
id title sort
1 a 4
2 b 2
3 c 3
4 d 4
5 e 5
6 f 6
and then plus 1 to #4 sort and any records after that
and we have
id title sort
1 a 4
2 b 2
3 c 3
4 d 5
5 e 6
6 f 7
and after sort
id title sort
2 b 2
3 c 3
1 a 4
4 d 5
6 e 6
6 f 7
it works fine but imagine we have 2,000,000 records and all records must be update...
method two
get sum sort of #3 and #4 and divide on 2 => (3+4)/2=3.5
and just put it for #1 sort
id title sort
2 b 2
3 c 3
1 a 3.5
4 d 4
5 e 5
6 f 6
it is work fine too but imagine thousand of this operation make big floats like 3.99999999999 and after a while its horrible
is there any mysql/mariadb trick or method for do this ?
Your "drop it half-way between items" method may be the best.
Let's go with BIGINT UNSIGNED since it gives you 64 bits in 8 bytes. Less good: DOUBLE would give you 53 bits in 8 bytes, and some funny business with exponents. DECIMAL gives you more bits at a cost of more bytes, while not eliminating the need for the following code.
You know which row to put it "after" based on user input?
Discover the row after by using ORDER BY ... ASC LIMIT 1.
Average the two values; check to see if the avg is equal either of them -- if so, you have a bad case.
Digression... 2M rows. Start with 2K, 4K, 6K, etc as the sort values (2M*2K = 4G, the limit of BIGINT UNSIGNED.)
This says you can squeeze 2K items between any adjacent pair. However, in the worst case of repeatedly inserting exactly after the first value, you get only 11 inserts before hitting the wall. 11 ~= log2(2000). That is, the re-sort is may be quick, but up to 1 time in 11, it will be costly.
(Please don't quibble between 2K meaning 2000 vs 2048; it does not matter to the algorithm.)
So, what to do when there is no room to insert a new sort value? Rebuilding the numbers would lock the table (of 2M rows) for "too long", so let's try to avoid that.
How about this:
Grab the 10 rows before and after (2 SELECTs with ORDER BY and LIMIT). Fix those sort values so that they are evenly spread out.
Possibly no issue with hitting the start or end of the table; it would be less than 20 rows. And there is a silent 0 and 4G-1 boundaries.
If the 20 rows are not enough, then broaden the span.
Do all this (including the original, simple, half-way code) in a transaction.
Use FOR UPDATE on all(?) SELECTs so that other threads are blocked.
Check for deadlocks. If encountered, start over completely. (The second try will probably find that the half-way attempt works fine -- because some other thread finished spreading the sort values out.)
Timing:
The half-way case, even with transaction, will probably take a millisecond or so.
The more complex case won't take much longer, in spite of locking and updating 20 rows.
You could probably handle 1K actions per second.
I am wondering if any of you would be able to help me. I am trying to loop through table 1 (which has duplicate values of the plant codes) and based on the unique plant codes, create a new record for the two other tables. For each unique Plant code I want to create a new row in the other two tables and regarding the non unique PtypeID I link any one of the PTypeID's for all inserts it doesnt matter which I choose and for the rest of the fields like name etc. I would like to set those myself, I am just stuck on the logic of how to insert based on looping through a certain table and adding to another. So here is the data:
Table 1
PlantCode PlantID PTypeID
MEX 1 10
USA 2 11
USA 2 12
AUS 3 13
CHL 4 14
Table 2
PTypeID PtypeName PRID
123 Supplier 1
23 General 2
45 Customer 3
90 Broker 4
90 Broker 5
Table 3
PCreatedDate PRID PRName
2005-03-21 14:44:27.157 1 Classification
2005-03-29 00:00:00.000 2 Follow Up
2005-04-13 09:27:17.720 3 Step 1
2005-04-13 10:31:37.680 4 Step 2
2005-04-13 10:32:17.663 5 General Process
Any help at all would be greatly appreciated
I'm unclear on what relationship there is between Table 1 and either of the other two, so this is going to be a bit general.
First, there are two options and both require a select statement to get the unique values of PlantCode out of table1, along with one of the PTypeId's associated with it, so let's do that:
select PlantCode, min(PTypeId)
from table1
group by PlantCode;
This gets the lowest valued PTypeId associated with the PlantCode. You could use max(PTypeId) instead which gets the highest value if you wanted: for 'USA' min will give you 11 and max will give you 12.
Having selected that data you can either write some code (C#, C++, java, whatever) to read through the results row by row and insert new data into table2 and table3. I'm not going to show that, but I'll show how the do it using pure SQL.
insert into table2 (PTypeId, PTypeName, PRID)
select PTypeId, 'YourChoiceOfName', 24 -- set PRID to 24 for all
from
(
select PlantCode, min(PTypeId) as PTypeId
from table1
group by PlantCode
) x;
and follow that with a similar insert.... select... for table3.
Hope that helps.
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.
At first I would like greet all Users and apologize for my english :).
I'm new user on this forum.
I have a question about MySQL queries.
I have table Items with let say 2 columns for example itemsID and ItemsQty.
itemsID ItemsQty
11 2
12 3
13 3
15 5
16 1
I need select itemsID but duplicated as many times as indicated in column ItemsQty.
itemsID ItemsQty
11 2
11 2
12 3
12 3
12 3
13 3
13 3
13 3
15 5
15 5
15 5
15 5
15 5
16 1
I tried that query:
SELECT items.itemsID, items.itemsQty
FROM base.items
LEFT OUTER JOIN
(
SELECT items.itemsQty AS Qty FROM base.items
) AS Numbers ON items.itemsQty <=Numbers.Qty
ORDER BY items.itemsID;
but it doesn't work correctly.
Thanks in advance for help.
SQL answer - Option 1
You need another table called numbers with the numbers 1 up to the maximum for ItemsQuantity
Table: NUMBERS
1
2
3
4
5
......
max number for ItemsQuantity
Then the following SELECT statement will work
SELECT ItemsID, ItemsQty
FROM originaltable
JOIN numbers
ON originaltable.ItemsQty >= numbers.number
ORDER BY ItemsID, number
See this fiddle -> you should always set-up a fiddle like this when you can - it makes everyone's life easier!!!
code answer - option 2
MySQL probably won't do what you want 'cleanly' without a second table (although some clever person might know how)
What is wrong with doing it with script?
Just run a SELECT itemsID, ItemsQty FROM table
Then when looping through the result just do (pseudo code as no language specified)
newArray = array(); // new array
While Rows Returned from database{ //loop all rows returned
loop number of times in column 'ItemsQty'{
newArray -> add 'ItemsID'
}
}//end of while loop
This will give you a new array
0 => 11
1 => 11
2 => 12
3 => 12
4 => 12
5 => 13
etc.
Select DISTINCT items.itemsID, items.itemsQty From base.items left outer join (select items.itemsQty as Qty from base.items) As Numbers On items.itemsQty <=Numbers.Qty
order by items.itemsID;
Use DISTINCT to remove duplicates. Read more here - http://dev.mysql.com/doc/refman/5.0/en/select.html
It seems like I understood what you asked differently than everyone else so I hope I answer you question. What I would basically do is -
create a new table for those changes.
Create a mysql procedure which given a line in the original table add new lines to the new table - http://dev.mysql.com/doc/refman/5.6/en/loop.html
Run this procedure for each line in the original table.
try this to get distinct values from both columns
SELECT DISTINCT itemsID FROM items
UNION
SELECT DISTINCT itemsQty FROM items