SQL Select statement separate values into two columns - sql

I have string value in the column Username.
Sample usernames:
USERNAME
--------
foobar123
john
smith23
steve
peter
king213
The user names with numbers at the end means that these users are no longer active. I want to separate these usernames into two columns Active and Not_Active in one Select Statement since i'll be using these for reports purposes.
Result should be:
Active Not_Active
john foobar123
steve smith23
peter king213
Query:
SELECT
Username,
(
CASE Username
WHEN '%[0-9]%' THEN 'Not'
ELSE 'Active'
END
)
FROM
Users;
I tried Case but I don't know how to get the username value.

Expanding on my comment reply to your original posting, you don't want the data in the same output result-set; instead you will want two result sets (i.e. two tables), each with the different criteria.
Note that you cannot use LIKE string matching (%) with the WHEN statement in SQL. You have to use it in a CASE WHEN statement (one without a "switch" expression)
-- Result set one: Active users
SELECT
UserName
FROM
Users
WHERE
UserName NOT LIKE '%[0-9]';
-- Result set two: Inactive users
SELECT
UserName
FROM
Users
WHERE
UserName LIKE '%[0-9]';
If you really want, you can combine these two queries into a single result-set with the data in different columns. This would be done by adding a ROW_NUMBER() column to each intermediate table, then doing a FULL OUTER JOIN on ROW_NUMBER(), however the output result would be meaningless and painful to iterate over in any consuming client code.
Another option might be a single result-set, with a computed IsActive column:
SELECT
UserName,
( CASE WHEN UserName NOT LIKE '%[0-9]' THEN 1 ELSE 0 END ) AS IsActive
FROM
Users
...which would be considerably easier to process in any consuming code.

this format of saving data is quite useful in this one column holds username and other holds status of the user
select username,
case username
when '%[0-9]% then inactive
else active
end as user_status
from table_1
username user_status
john active
john123 inactive

Related

How to return input + string if value doesn't exist in DB?

I want to query a table for an array with user names and I want to not only get the name and user ids if found but also if it wasn't found, I want a string.
I have the following query using Bigquery
SELECT
user_id,
name as user_name
FROM table
WHERE name IN ('userone', 'usertwo', 'userfourtysix')
Current Output
user_ID
user_name
001
userone
002
usertwo
Desire Output
user_ID
user_name
001
userone
002
usertwo
NULL
userfourtysix
or a string with input + 'doesn't exist'
Is that possible with SQL?
It is possible in SQL but not with the IN clause, since you are filtering out any values that don't match with the IN clause.
You need to rewrite your query to take advantage of JOINS.
Create a CTE with the list of names you want to manage
Perform a left join so that values on the CTE are preserved even if there's no match in the right table.

SQL Server table data retrieval

I have attended an interview recently, and the interviewer asked me this question:
UserId UserName
1 Name1
1 Name2
2 Name3
Here he wants me to retrieve either Name1 or Name2 using where condition?
How can I get the result?
I wrote like
select Username
from Users
where Username = 'Name1' or Username = 'Name2'
but here both the conditions are satisfied so two records are returned... What will be the query to retrieve the data?
I think you mean something like this:
SELECT UserName FROM Users
WHERE UserName IN(NAME1, NAME2)
LIMIT 1
That would sort of randomly select the first one you come across (out of NAME1 and NAME2). I'm assuming that you don't have to select a specific one, and that there aren't more instances of the names that also need to get selected, all as per your example.

SQL command to clear specific text

Trying to run a SQL command that reads * from my database but I need it to seek specific text in the email field and return a null if it doesn't equal. Example, I'm trying to filter out all emails in our database that are not internal email addresses, so it would need to filter out any that don't have our company name in it.
I was able to filter this with a LIKE command, but it just simply ignores the rest of the fields in the results. I know access has the IIf(InStr command, so I'm hoping there is something similar in SQL
Not sure I fully understand, but something like this may work for you.
USE Server
SELECT
firstName AS EmployeeFirstname
, lastName AS EmployeeLastname
, title AS EmployeeTitle
, id AS EmployeeID
,
Case
When emailAddress Like '%#mycompany.com'
Then emailAddress
Else Null
End AS EmployeeEmailAddress
FROM db.Information
WHERE ISNUMERIC(id)<> 0
AND empStatus = 'A'
So what this will do is give you the rows regardless of what email they have (still taking into account your other selections of ISNUMERIC(id)<> 0 AND empStatus = 'A'). But in those rows, if the email is your company they would display and if not the field would be Null. Obviously change the “mycompany.com” it the Like to whatever string you actually need to search for,
If you want to exclude all records where the company is not in the email address, add
where
emailAddress not like '%companyname%'
If you want to blank out the non-company email addresses, you can use case
Select
case when emailaddress not like '%company%' then null else emailaddress end

How do I check if all posts from a joined table has the same value in a column?

I'm building a BI report for a client where there is a 1-n related join involved.
The joined table has a field for employee ID (EmplId).
The query that I've built for this report is supposed to give a 1 in its field "OneEmployee" if all the related posts have the same employee in the EmplId field, null if it's different employees, i.e:
TaskTrans
TaskTransHours > EmplId: 'John'
TaskTransHours > EmplId: 'John'
This should give a 1 in the said field in the query
TaskTrans
TaskTransHours > EmplId: 'John'
TaskTransHours > EmplId: 'George'
This should leave the said field blank
The idea is to create a field where a case function checks this and returns the correct value. But my problem is whereas there is a way to check for this through SQL.
select not count(*) from your_table
where employee_id = GIVEN_ID
and your_field not in ( select min(your_field)
from your_table
where employee_id = GIVEN_ID);
Note: my first idea was to use LIMIT 1 in the inner query, but MYSQL didn't like it, so min it was - the points to use any, but only one. Min should work, but the field should be indexed, then this query will actually execute rather fast, as only indexes would be used (obviously employee_id should also be indexed).
Note2: Do not get too confused with not in front of count(*), you want 1 when there is none that is different, I count different ones, and then give you the not count(*), which will be one if count is 0, otherwise 0.
Seems a job for a window COUNT():
SELECT
…,
CASE COUNT(DISTINCT TaskTransHours.EmplId) OVER () WHEN 1 THEN 1 END
AS OneEmployee
FROM …

SQL: Sorting By Email Domain Name

What is the shortest and/or efficient SQL statement to sort a table with a column of email address by it's DOMAIN name fragment?
That's essentially ignoring whatever is before "#" in the email addresses and case-insensitive. Let's ignore the internationalized domain names for this one.
Target at: mySQL, MSSQL, Oracle
Sample data from TABLE1
id name email
------------------------------------------
1 John Doe johndoe#domain.com
2 Jane Doe janedoe#helloworld.com
3 Ali Baba ali#babaland.com
4 Foo Bar foo#worldof.bar.net
5 Tarrack Ocama me#am-no-president.org
Order By Email
SELECT * FROM TABLE1 ORDER BY EMAIL ASC
id name email
------------------------------------------
3 Ali Baba ali#babaland.com
4 Foo Bar foo#worldof.bar.net
2 Jane Doe janedoe#helloworld.com
1 John Doe johndoe#domain.com
5 Tarrack Ocama me#am-no-president.org
Order By Domain
SELECT * FROM TABLE1 ORDER BY ?????? ASC
id name email
------------------------------------------
5 Tarrack Ocama me#am-no-president.org
3 Ali Baba ali#babaland.com
1 John Doe johndoe#domain.com
2 Jane Doe janedoe#helloworld.com
4 Foo Bar foo#worldof.bar.net
EDIT:
I am not asking for a single SQL statement that will work on all 3 or more SQL engines. Any contribution are welcomed. :)
Try this
Query(For Sql Server):
select * from mytbl
order by SUBSTRING(email,(CHARINDEX('#',email)+1),1)
Query(For Oracle):
select * from mytbl
order by substr(email,INSTR(email,'#',1) + 1,1)
Query(for MySQL)
pygorex1 already answered
Output:
id name email
5 Tarrack Ocama me#am-no-president.org
3 Ali Baba ali#babaland.com
1 John Doe johndoe#domain.com
2 Jane Doe janedoe#helloworld.com
4 Foo Bar foo#worldof.bar.net
For MySQL:
select email, SUBSTRING_INDEX(email,'#',-1) AS domain from user order by domain desc;
For case-insensitive:
select user_id, username, email, LOWER(SUBSTRING_INDEX(email,'#',-1)) AS domain from user order by domain desc;
If you want this solution to scale at all, you should not be trying to extract sub-columns. Per-row functions are notoriously slow as the table gets bigger and bigger.
The right thing to do in this case is to move the cost of extraction from select (where it happens a lot) to insert/update where it happens less (in most normal databases). By incurring the cost only on insert and update, you greatly increase the overall efficiency of the database, since that's the only point in time where you need to do it (i.e., it's the only time when the data changes).
In order to achieve this, split the email address into two distinct columns in the table, email_user and email_domain). Then you can either split it in your application before insertion/update or use a trigger (or pre-computed columns if your DBMS supports it) in the database to do it automatically.
Then you sort on email_domain and, when you want the full email address, you use email_name|'#'|email_domain.
Alternatively, you can keep the full email column and use a trigger to duplicate just the domain part in email_domain, then you never need to worry about concatenating the columns to get the full email address.
It's perfectly acceptable to revert from 3NF for performance reasons provided you know what you're doing. In this case, the data in the two columns can't get out of sync simply because the triggers won't allow it. It's a good way to trade disk space (relatively cheap) for performance (we always want more of that).
And, if you're the sort that doesn't like reverting from 3NF at all, the email_name/email_domain solution will fix that.
This is also assuming you just want to handle email addresses of the form a#b - there are other valid email addresses but I can't recall seeing any of them in the wild for years.
For SQL Server, you could add a computed column to your table with extracts the domain into a separate field. If you persist that column into the table, you can use it like any other field and even put an index on it, to speed things up, if you query by domain name a lot:
ALTER TABLE Table1
ADD DomainName AS
SUBSTRING(email, CHARINDEX('#', email)+1, 500) PERSISTED
So now your table would have an additional column "DomainName" which contains anything after the "#" sign in your e-mail address.
Assuming you really must cater for MySQL, Oracle and MSSQL .. the most efficient way might be to store the account name and domain name in two separate fields. The you can do your ordering:
select id,name,email from table order by name
select id,name,email,account,domain from table order by email
select id,name,email,account,domain from table order by domain,account
as donnie points out, string manipulation functions are non standard .. that is why you will have to keep the data redundant!
I've added account and domain to the third query, since I seam to recall not all DBMSs will sort a query on a field that isn't in the selected fields.
This will work with Oracle:
select id,name,email,substr(email,instr(email,'#',1)+1) as domain
from table1
order by domain asc
For postgres the query is:
SELECT * FROM table
ORDER BY SUBSTRING(email,(position('#' in email) + 1),252)
The value 252 is the longest allowed domain (since, the max length of an email is 254 including the local part, the #, and the domain.
See this for more details: What is the maximum length of a valid email address?
You are going to have to use the text manipulation functions to parse out the domain. Then order by the new column.
MySQL, an intelligent combination of right() and instr()
SQL Server, right() and patindex()
Oracle, instr() and substr()
And, as said by someone else, if you have a decent to high record count, wrapping your email field in functions in you where clause will make it so the RDBMS can't use any index you might have on that column. So, you may want to consider creating a computed column which holds the domain.
If you have million records, I suggest you to create new column with domain name only.
My suggestion would be (for mysql):
SELECT
LOWER(email) AS email,
SUBSTRING_INDEX(email, '#', + 1) AS account,
REPLACE(SUBSTRING_INDEX(email, '#', -1), CONCAT('.',SUBSTRING_INDEX(email, '.', -1)),'') -- 2nd part of mail - tld.
AS domain,
CONCAT('.',SUBSTRING_INDEX(email, '.', -1)) AS tld
FROM
********
ORDER BY domain, email ASC;
And then just add a WHERE...
The original answer for SQL Server didn't work for me....
Here is a version for SQL Server...
select SUBSTRING(email,(CHARINDEX('#',email)+1),len(email)), count(*)
from table_name
group by SUBSTRING(email,(CHARINDEX('#',email)+1),len(email))
order by count(*) desc
work smarter not harder:
SELECT REVERSE(SUBSTRING_INDEX(REVERSE(SUBSTRING(emails.email, POSITION('#' IN emails.email)+1)),'.',2)) FROM emails