I am having some trouble finding an answer for this one, so I apologize if it was somewhere else.
I have a table 'dbo.MileageImport' that has the following layout which I pulled to find duplicate entries:
|KEY | DATA |
---------------------
|V9864653 | 180288 |
|V9864653 | 22189 |
|V9864811 | 11464 |
|V9864811 | 12688 |
What I am having troubles with is when I run the following SQL in a DB2 environment:
SELECT KEY, MIN(DATA)
FROM dbo.MileageImport
GROUP BY KEY
HAVING (COUNT(KEY)>1);
It ends up pulling the following data:
|KEY | DATA |
---------------------
|V9864811 | 11464 |
|V9864653 | 180288 |
For some reason it's pulling the MIN value for V9864811, but not V9864653. If I inverse that and put MAX instead of MIN, it pulls the opposite values.
Is there something I am missing here so I can pull the MIN DATA value for only duplicate KEY records, or is there another way to do this? The report where this data comes from changes from month to month, so there could be different keys that end up being duplicated that I need to correct. Ultimately I am turning this into a DELETE statement to delete the lower of the two (or more) duplicated mileage entries.
Is your DATA column numerical? or a VARCHAR?
If you find its better to change it to a number if you can, maybe an integer if you aren't having any fractions and its just round numbers.
if not, then you could cast them to an integer value, but if there are lots of transactions or its a big table it will be slow and not ideal. Its bad practise to do that if you could just change the datatype!
SELECT KEY, MIN(CAST(DATA as Int))
FROM dbo.MileageImport
GROUP BY KEY
HAVING (COUNT(KEY)>1)
Related
I am using Impala for querying parquet-tables and cannot find a solution to increment an integer-column ranging from 1..n. The column is supposed to be used as ID-reference. Currently I am aware of the uuid() function, which
Returns a universal unique identifier, a 128-bit value encoded as a string with groups of hexadecimal digits separated by dashes.
Anyhow, this is not suitable for me since I have to pass the ID to another system which requests an ID in style of 1..n. I also already know that Impala has no auto-increment-implementation.
The desired result should look like:
-- UUID() provided as example - I want to achieve the `my_id`-column.
| my_id | example_uuid | some_content |
|-------|--------------|--------------|
| 1 | 50d53ca4-b...| "a" |
| 2 | 6ba8dd54-1...| "b" |
| 3 | 515362df-f...| "c" |
| 4 | a52db5e9-e...| "d" |
|-------|--------------|--------------|
How can I achieve the desired result (integer-ID ranging from 1..n)?
Note: This question differs from this one which specifically handles Kudu-tables. However, answers should be applicable for this question as well.
Since other Q&A's like this one only came up with uuid()-alike answers, I put some thought in it and finally came up with this solution:
SELECT
row_number() OVER (PARTITION BY "dummy" ORDER BY "dummy") as my_id
, some_content
FROM some_table
row_number() generates a continuous integer-number over a provided partition. Unlike rank(), row_number() always provides an incremented number on its partition (even if duplicates occur)
PARTITION BY "dummy" partitions the entire table into one partition. This works since "dummy" is interpreted in the execution graph as temporary column yielding only the String-value "dummy". Thus, also something analog to "dummy" works.
ORDER BY is required in order to generate the increment. Since we don't care about the order in this example (otherwise just set your respective column), also use the "dummy"-workaround.
The command creates the desired incremental ID without any nested SQL-statements or other tricks.
| my_id | some_content |
|-------|--------------|
| 1 | "a" |
| 2 | "b" |
| 3 | "c" |
| 4 | "d" |
|-------|--------------|
I used Markus's answer for a large partitioned table and found that I was getting duplicate ids. I think the ids were only unique within their partition; possibly PARTITION BY "dummy" leads Impala to think that each partition can execute row_number() on its own. I was able to get it working by specifying an actual column to order by and no partition by:
SELECT
row_number() OVER (ORDER BY actual_column) as my_id
, some_content
FROM some_table
It doesn't seem to matter whether the values in the column are unique (mine weren't), but using the actual partition key might result in the same issue as the "dummy" column.
Understandably, it took a lot longer to run than the dummy version.
I apologise if this has been asked before. I'm still not certain how to phrase my question for the title, so wasn't sure what to search for.
I have a hundred or so databases in the same instance, one for each of my customers, named for the customer, and they all have the same structure. I want to select a single result set that includes the database name along with the most recent date entry in one of the tables. I can pull the database names from sys.databases, but then for each database I want to select the most recent date from Events.Date_Logged so that my result set looks something like this:
_______________________________
| | |
|Cust_Name |Latest_Event |
|_______________|_______________|
| | |
|Customer1 |01/02/2020 |
|_______________|_______________|
| | |
|Customer2 |02/02/2020 |
|_______________|_______________|
| | |
|Customer3 |03/02/2020 |
|_______________|_______________|
I'm really struggling with the syntax though. I either get just a single row returned or every single event for each customer. I think my joins are as rusty as hell.
Any help would be appreciated.
What I suggest you do:
Declare a result variable (of type table)
Use a cursor to go over every database
Inside the cursor: do a select top 1 ... order by date desc to get the most recent record. Save this result in the result variable.
After the cursor print the result variable.
That should do the trick.
it is possible to store a function IN the table to automatically sum a group of columns and store the result in a final column?
ie:
+----+------------+-----------+-------------+------------+
| id | appleCount | pearCount | bananaCount | totalFruit |
+----+------------+-----------+-------------+------------+
| 1 | 300 | 60 | 120 | 480 |
+----+------------+-----------+-------------+------------+
where the column totalFruit is automatically calculated from the previous three columns and updated as the other columns update. in this specific application, there is ONLY going to be the one row. it would be spanky-handy to be able to just push the updated counts and then pull the calculated total out. i seem to recall reading about this ability somewhere, but for the life of me, i can't recall where... :poop:
if there is not way to do this, that's cool. but if there is... :smile:
TIA!
WR!
Yes, it is possible. But is it worth it? It is simple enough to do
SELECT ...
appleCount + pearCount + bananaCount AS totalFruit
...
See MariaDB Generated Columns for how to generate the extra column -- either as a real extra column or "virtual". What version of MariaDB?--There are a number of changes over time.
(MySQL users: 5.7.6 has a similar MySQL Generated Columns.)
I have a series of queries that generate reports that contain chemical data. There are two compounds A and B where A is the total amount and B is a speciated amount (like total iron and ferrous iron, for example).
There are about one hundred total compounds in the query result, and I need a criteria to filter the results such that if both Compounds A and B are present, only Compound B is displayed. So far I've tried adding a few iif statements to the criteria section in the query builder with no luck.
Here is what I have so far:
SELECT Table1.KEY_ANLT
FROM Table1
WHERE (((Table1.KEY_ANLT)=IIf([Table1].[KEY_ANLT]=1223 And [Table1].[KEY_ANLT]=70,70,1223)));
This filters out Compound A but does not include the rest of the compounds. How can I modify the query to also include the other compounds?
So, to clarify some of the comments above, the problem here is you don't have (or haven't specified above) a way to identify values that go together. You gave 70 and 1223 as an example, but if you gave us a list of all the numbers, how would we be able to identify which ones go together? You might say "chemistry expertise", but that's based on another column with the compounds' names, right? So really, your query should use that column. But then there's still the problem of how to connect associated names (e.g., "total iron" and "ferrous iron" might be connected because they both have the word "iron", but what about "permanganate" and "manganese"?). In short, you need another column to specify the thing in common between these separate rows, whether it's element, ion, charge, etc. You would also need a column identifying which row in each "group" you would want to include in your query (or, which ones to exclude). For example:
+----------+-----------------+---------+---------+
| KEY_ANLT | Compound | Element | Primary |
+----------+-----------------+---------+---------+
| 70 | total iron | Fe | Y |
| 1223 | ferrous iron | Fe | |
| 1224 | ferric iron | Fe | |
| 900 | total manganese | Mn | Y |
| 901 | permanganate | Mn | |
+----------+-----------------+---------+---------+
Then, to get a query that shows just the "primary" rows, it's pretty trivial:
SELECT * FROM Table1 WHERE Primary='Y';
Without that [Primary] column, you'd have to decide how to choose each row. Perhaps you'd want the one with the smallest KEY_ANLT?
SELECT Table1.*
FROM
(SELECT Element, min(KEY_ANLT) AS MinKey FROM Table1 GROUP BY Element) AS Subquery
INNER JOIN Table1 ON
Subquery.Element=Table1.Element AND
Subquery.MinKey=Table1.KEY_ANLT
The reason your query doesn't work is that the WHERE clause operates row-by-row, and doesn't compare different rows to one another. So in your SQL:
IIf([Table1].[KEY_ANLT]=1223 And [Table1].[KEY_ANLT]=70,70,1223)
NONE of the rows will evaluate this as 70, because no single row has KEY_ANLT=1223 AND KEY_ANLT=70. Each row only has one value for KEY_ANLT. So then that IIF expression evaluates as 1223 for every row, and your condition will only return rows where KEY_ANLT=1223 (compound B).
I have a table with data along the (massively simplified) lines of:
User | Value
-----|------
UsrA | 100
UsrA | 102
UsrB | 100
UsrA | 100
UsrB | 101
and, for reasons far to obscure to go into, I need to store the COUNT of each value in a table for future retrieval - ending up with something like
User | Value100Count | Value101Count | Value102Count
-----|---------------|---------------|--------------
UsrA | 2 | 0 | 1
UsrB | 1 | 1 | 0
However, there could be up to 255 different Values - meaning potentially 255 different ValueXCount columns. I know this is a horrible way to do things, but is there an easy way to get the data into a format that can be easily INSERTed into the destination table? Is there a better way to store the COUNT of values per user (unfortunately I do need to store this information; grabbing it from the source table each time isn't an option)?
The whole thing isn't very pretty, but you know that, rather than your table with 255 columns I'd consider setting up another table with:
User | Value | CountOfValue
And set a primary key over User and Value.
You could then insert the count's for given user/value combos into the CountOfValue field
As I said, the design is horrible and it feels like you would be better off starting from scratch, normalizing and doing counts live.
Check out indexed views. You can maintain the table automatically, with integrity and as a bonus it can get used in queries that already do count(*) on that data.