For a user logging table I have in a SQL database, I track the some of the parameters off of a report request. The report allows multiple ID's to be passed to it and I store all of those in a single column in the database column. If this were to be a normalized set of data, there would definitely be an additional table setup for this, but this is what was inherited...
I've now been asked to give a quick count of the number of times a report was run with more than 2 ID's passed to it. I can easily get the number of records that have more than 1 report requested because they all include a comma.
What I need to do next is count the number of times a comma appears in a column. How do you do this in SQL?
--count the number of times more than 1 report was requested in the record
select
count(*) as cnt
from
[table]
where
RequestedReportParams Like '%,%'
SELECT LEN(RequestedReportParams) - LEN(REPLACE(RequestedReportParams, ',', ''))
FROM YourTable
WHERE .....
This is simply comparing the length of the column with the commas, with the length of the value with the commas removed, to give you the difference (i.e. the number of commas)
It seems the quick and dirty way to answer the question you've been asked would be to do this:
select
count(*) as cnt
FROM
[table]
WHERE
RequestedReportParams Like '%,%,%'
Related
I am trying to write a query to find out whether a record exist more than one or not in a given period of time. And even if it exist, how many times the same record has been repeated.
Now to solve this issue, I have sorted the records.
select * from table_name where date = ? and date > ? order by email
And trying to count the number of times the same record exist.But I am not able to figure out a way to count the number of times the same record exists.
Here is a problem.The image below holds the basic data structure.
Here is the expected output for a year
The table above holds Xyz name and xyz#email.com data three times. And the name Abc and email abc#email.com two times and the third record name Def and email def#email.com two times. Now what I am trying to figure out a way to find out the number of times each records are being repeated in a given period of time using a single query. I am thinking to make use of recursion on a record and count till it didn't find a different record after sorting it. But using recursion on every records seems expensive.
Is there a better solution to solve this problem ?
Regards
Group and count.
SELECT column_to_compare1, column_to_compare2, COUNT(*)
FROM table_name
WHERE [date] BETWEEN #date1 AND #date2
GROUP BY column_to_compare1, column_to_compare2
HAVING COUNT(*) > 1 -- IF YOU WANT TO ONLY INCLUDE RECORDS WITH DUPLICATES
Between is inclusive, so you can adjust your dates with DATEADD if you really want between.
You can use the COUNT function to do this.
To do this using your own query:
SELECT Name, Email, COUNT(*) AS count
FROM table_name
WHERE date BETWEEN '01/01/2005' AND '31/12/2005'
GROUP BY Name, Email
However your example query is poor so I cannot give you a better solution. Here is an example of this working: SQL Fiddle
EDIT: Updated my solution to match you expected output.
I'm having a table with an id and a name.
I'm getting a list of id's and i need their names.
In my knowledge i have two options.
Create a forloop in my code which executes:
SELECT name from table where id=x
where x is always a number.
or I'm write a single query like this:
SELECT name from table where id=1 OR id=2 OR id=3
The list of id's and names is enormous so i think you wouldn't want that.
The problem of id's is the id is not always a number but a random generated id containting numbers and characters. So talking about ranges is not a solution.
I'm asking this in a performance point of view.
What's a nice solution for this problem?
SQLite has limits on the size of a query, so if there is no known upper limit on the number of IDs, you cannot use a single query.
When you are reading multiple rows (note: IN (1, 2, 3) is easier than many ORs), you don't know to which ID a name belongs unless you also SELECT that, or sort the results by the ID.
There should be no noticeable difference in performance; SQLite is an embedded database without client/server communication overhead, and the query does not need to be parsed again if you use a prepared statement.
A "nice" solution is using the INoperator:
SELECT name from table where id in (1,2,3)
Also, the IN operator is syntactic sugar built for exactly this purpose..
SELECT name from table where id IN (1,2,3,4,5,6.....)
Hoping that you are getting the list of ID's on which you have to perform a query for names as input temp table #InputIDTable,
SELECT name from table WHERE ID IN (SELECT id from #InputIDTable)
I like to request your help. I can get the results seperated but now i want to create a query which has it perfect for a external person. my explanation:
I have a statistics database with in this database a table when some records comes in and each records has several columns with values etc...
Now one of these columns is called "MT"
MT Column can have only one of the following values per records: A,B,C,D,E
The records also have a columne called TotalAmount which indicate a size of a value outside the database. This TotalAmount column is numeric without decimals and can have a value between 1 and 10.000.
And the last part is the records it self, the table has X amount of records.
So Basicly i need to create a query which seperates each MT value and calculates the amount of records per MT and the sum of TotalAmount.
This is on SQL Server 2005.
Many thanks for your assistance!
Very hard to guess without a full db schema. But I think you need.
SELECT MT, Count(*), SUM (TotalAmout)
FROM YourTable
GROUP BY MT
I'm using Postgres and I'd like to know how to change row information within a query, Let's say I have a column called Numbers and it's got rows going 1,2,3,4,5 how could I edit the information in those rows? let's say I want the query to display 1,1,1,1,5 how would I write in a query that each row should be changed to 1 unless it's 5? Again it's only to change it within the Query, I'm not trying to do an UPDATE I realize how newbish this is on my part but I couldn't find this on google.
SELECT
CASE WHEN Numbers <> 5 THEN 1 ELSE Numbers END
FROM table
See 9.12. Conditional Expressions
Select Null as Empty from (select * from TblMetaData)
Looks like, it is trying to get null rows for the same number of rows in tblMetaData.
EDIT: This could be written as
SELECT Null AS Empty FROM tblMetaData
It will yield a result set with one column named Empty which only contains NULL values. The number of rows will be equal to the number of rows available in TblMetaData.
It looks like the result of one of two possible situations:
The developer was getting paid per line, and threw in that query. It was probably originally structured to take more than one line.
The developer was incompetent and this was the only way they could think of to generate a bunch of null values.
The query returns a null value from each line of the table, so the only real information in the result is the number of records in the table.
This can of course be found out a lot more efficently using:
select count(*) as Count from TblMetaData
It's possible that the developer was not at all aware of the count aggregate (or how to search the web) and tried to get the number of records while making the result as small as possible.
It often used in this expression
select * from TableA where exists
(select null from TableB where TableB.Col1=TableA.Col1)
it can be used to give the number of rows in the table TblMetaData with the column's name denoting the first letter of empty(in this case only).
like suppose you gave
Select Null as Empty from (select * from TblMetaData)
so it will give
E
n rows selected
here n is the number of rows in the table.
suppose you gave
Select Null as XYZ from (select * from TblMetaData)
then it would be same but the column's name would change like
X
n rows selected