for example :
I have a table with student ID and student grades
-----------------------
ID | grades
-----------------------
1 | 80
2 | 28
-----------------------
I want to get 0 when I query about ID = 3
can I do that ?
like select grades from student where id = 3 .
I want to get 0 because ID is not in the table
Run a select command with the reserved function called count:
select count(*) from STUDENT.GRADES where ID=3
It should be just like that.
Maybe this will do what you want:
SELECT ID, MAX(Grades)
FROM (SELECT ID, Grade FROM Students WHERE ID = 3
UNION
VALUES (3, 0) -- Not certain of syntax here
)
GROUP BY ID
The basic idea is that students present in the table will have two rows and the MAX will pick their proper grade (assuming that there are no circumstances where the grade is coded as a negative value). Students that are not represented will have just the one row with a grade of 0. The repeated 3 is the ID of the student being sought.
Have fun chasing down the full syntax. I started at Queries in the DB2 9.7 Information Centre, but ran out of patience before I got a good answer — and I don't have DB2 to experiment on. You might need to write SELECT ID, Grades FROM VALUES (3, 0), or there might be some other magical incantation that does the job. You could probably use SELECT 3 AS ID, 0 AS Grades FROM SYSIBM.SYSTABLES WHERE TABID = 1, but that's a clumsy expression.
I've kept with the column name Grades (plural) even though it looks like it contains one grade. It is depressing how often people ask questions about anonymous tables.
Related
Can anyone help? My trouble is that people might have the same id or different and have different name spellings. If I group by id (which is not the primary key) I get a different amount of rows than if I group by ID and name. How do I just group by ID, while still having the ID and Name in the select?
Create Table Client(ID Int, Name Varchar(15))
Insert Into Client VALUES(11,'Batman'),(22,'Batman'),(33,'Robin'),(44,'Joker'),(44,'The Joker'),(33,'Robin')
Select Count(ID) From Client
Select * From Client
--This returns 4 rows as it should
Select Count (ID)
From Client
Group By ID
--This returns 5 rows because Joker and The Joker have different names, but the same ID. I want to count by ID and not the name, since so many have typos.
Select Count (ID), [Name] , ID
From Client
Group By ID, [Name]
How do I do this and have it work?
Select Count (ID), [Name] , ID
From Client
Group By ID --<< Always throws and error unless I include Name, which
--returns too many rows.
It should return
Count Name ID
1 Batman 11
1 Batman 22
2 Joker 44 --<< Correct
2 Robin 33
And not
Count Name ID
1 Batman 11
1 Batman 22
2 Robin 33
1 Joker 44 --Wrong
1 The Joker 44 --Wrong
using select count(*) from ClientLog will tell you exactly how many records there are in your table. If your ID field is the primary key, then select count(ID) from ClientLog should return the same number.
Your first query is a little confusing, because you're grouping by ID but not displaying the ID. So you're likely getting a row for each record, where the row value is 1.
Your 2nd query is also a bit confusing, because there's no aggregation happening (since your ID field is unique).
What specifically are you trying to obtain in your query (if anything besides just how many records you have in your table)?
I have an SQL Server 2012 table with ID, First Name and Last name. The ID is unique per person but due to an error in the historical feed, different people were assigned the same id.
------------------------------
ID FirstName LastName
------------------------------
1 ABC M
1 ABC M
1 ABC M
1 ABC N
2 BCD S
3 CDE T
4 DEF T
4 DEG T
In this case, the people with ID’s 1 are different (their last name is clearly different) but they have the same ID. How do I query and get the result? The table in this case has millions of rows. If it was a smaller table, I would probably have queried all ID’s with a count > 1 and filtered them in an excel.
What I am trying to do is, get a list of all such ID's which have been assigned to two different users.
Any ideas or help would be very appreciated.
Edit: I dont think I framed the question very well.
There are two ID's which are present multiple time. 1 and 4. The rows with id 4 are identical. I dont want this in my result. The rows with ID 1, although the first name is same, the last name is different for 1 row. I want only those ID's whose ID is same but one of the first or last names is different.
I tried loading ID's which have multiple occurrences into a temp table and tried to compare it against the parent table albeit unsuccessfully. Any other ideas that I can try and implement?
SELECT
ID
FROM
<<Table>>
GROUP BY
ID
HAVING
COUNT(*) > 1;
SELECT *
FROM myTable
WHERE ID IN (
SELECT ID
FROM myTable
GROUP BY ID
HAVING MAX(LastName) <> MIN(LastName) OR MAX(FirstName) <> MIN(FirstName)
)
ORDER BY ID, LASTNAME
I need to write an sql query that will pull back the data that meets several groups of criteria from the same table. The easiest way to describe is to imagine using an SQL "in" clause but instead of the internals of that clause being "or"s joining the parameters you want it to match it is instead an "and".
I attempted to use count to verify the correct amount of data was pulled back for each "in" statement but the count can't always be trusted due to other entries being similar for each column.
A sample table might be this:
id count animal
--- ----- ------
1 5 puppy
1 6 cat
1 6 puppy
So, now I need a query that will pull back all entries with an id of 1 and a count of 5 and 6 and an animal of puppy and cat. I pretty much need to verify the entire path of the table entry to know I want to pull it back. Is there any built in function that can do this? Do I need to use a recursive CTE to dig deep after confirming that one set of criteria is met? Thanks for any help.
If I got it right
with cnt as(
select id
from tbl
where [count] in (5,6) and animal in ('puppy', 'cat')
group by id
having count(distinct[count])=2 and count(distinct animal)=2
)
select id, [count], animal
from tbl
where id in (select id from cnt);
It's kind of confusing what you're looking for exactly but can you not use or's and ands?
select id, count, animal
from table
where id = 1 and
(count = 5 or count = 6) and
(animal = puppy or anmial = cat)
I think you just want:
select t.*
from t
where id = 1 and
count in (5, 6) and
animal in ('puppy', 'cat');
EDIT:
If you want them all in the same row, just rearrange the conditions:
select t.*
from t
where id = 1 and
( (count = 5 and animal = 'puppy') or
(count = 6 and animal = 'cat')
);
this question was probably asked somewhere but I can't seem to phrase it correctly in the search to find an accurate answer.
I'm doing a query on a Postgres DB, it has quite a few joins, the results are something like this:
WON | name | item
1 Joe A
1 Joe B
2 Smith A
So one row for each entry, I need to somehow get the result back as such:
WON | name | item
1 Joe A, B
2 Smith A
This can be done in the query or with NodeJS, there are hundreds to thousands of results for the query, so getting a distinct row (WON 1) then searching the DB for all entries that match it then repeating for the rest isn't feasible, so this may be better done in Node / Javascript, but I'm somewhat new to that, what would be a (somewhat) efficient way to do this?
If there IS a way to do this in the query itself then that would be my preference though.
Thanks
A sql approach:
SELECT won, name
,STRING_AGG(item, ',' ORDER BY item) AS items
FROM myTable
GROUP BY won, name
ORDER BY won, name
You can use GROUP BY and string_agg to cancat rows, somelike this:
Create table:
CREATE TABLE test
(
won int,
name character varying(255),
item character varying(255)
);
insert into test (won, name, item) values (1,'Joe', 'A'),(1, 'Joe', 'B'),(2, 'Smith', 'A')
And do this in the query:
select won, name, string_agg(item, ',') from test group by won, name order by won
See this example in sqlFiddle
Goal is to replace a integer value that is returned in a SQL query with the char value that the number represents. For example:
A table attribute labeled ‘Sport’ is defined as a integer value between 1-4. 1 = Basketball, 2 = Hockey, etc. Below is the database table and then the desired output.
Database Table:
Player Team Sport
--------------------------
Bob Blue 1
Roy Red 3
Sarah Pink 4
Desired Outputs:
Player Team Sport
------------------------------
Bob Blue Basketball
Roy Red Soccer
Sarah Pink Kickball
What is best practice to translate these integer values for String values? Use SQL to translate the values prior to passing to program? Use scripting language to change the value within the program? Change database design?
The database should hold the values and you should perform a join to another table which has that data in it.
So you should have a table which has say a list of people
ID Name FavSport
1 Alex 4
2 Gnats 2
And then another table which has a list of the sports
ID Sport
1 Basketball
2 Football
3 Soccer
4 Kickball
Then you would do a join between these tables
select people.name, sports.sport
from people, sports
where people.favsport = sports.ID
which would give you back
Name Sport
Alex Kickball
Gnat Football
You could also use a case statement eg. just using the people table from above you could write something like
select name,
case
when favsport = 1 then 'Basketball'
when favsport = 2 then 'Football'
when favsport = 3 then 'Soccer'
else 'Kickball'
end as "Sport"
from people
But that is certainly not best practice.
MySQL has a CASE statement. The following works in SQL Server:
SELECT
CASE MyColumnName
WHEN 1 THEN 'First'
WHEN 2 THEN 'Second'
WHEN 3 THEN 'Third'
ELSE 'Other'
END
In oracle you can use the DECODE function which would provide a solution where the design of the database is beyond your control.
Directly from the oracle documentation:
Example: This example decodes the value warehouse_id. If warehouse_id is 1, then the function returns 'Southlake'; if warehouse_id is 2, then it returns 'San Francisco'; and so forth. If warehouse_id is not 1, 2, 3, or 4, then the function returns 'Non domestic'.
SELECT product_id,
DECODE (warehouse_id, 1, 'Southlake',
2, 'San Francisco',
3, 'New Jersey',
4, 'Seattle',
'Non domestic') "Location"
FROM inventories
WHERE product_id < 1775
ORDER BY product_id, "Location";
The CASE expression could help. However, it may be even faster to have a small table with an int primary key and a name string such as
1 baseball
2 football
etc, and JOIN it appropriately in the query.
Do you think it would be helpful to store these relationships between integers and strings in the database itself? As long as you have to store these relationships, it makes sense to store it close to your data (in the database) instead of in your code where it can get lost. If you use this solution, this would make the integer a foreign key to values in another table. You store integers in another table, say sports, with sport_id and sport, and join them as part of your query.
Instead of SELECT * FROM my_table you would SELECT * from my_table and use the appropriate join. If not every row in your main column has a corresponding sport, you could use a left join, otherwise selecting from both tables and using = in the where clause is probably sufficient.
definitely have the DB hold the string values. I am not a DB expert by any means, but I would recommend that you create a table that holds the strings and their corresponding integer values. From there, you can define a relationship between the two tables and then do a JOIN in the select to pull the string version of the integer.
tblSport Columns
------------
SportID int (PK, eg. 12)
SportName varchar (eg. "Tennis")
tblFriend Columns
------------
FriendID int (PK)
FriendName (eg. "Joe")
LikesSportID (eg. 12)
In this example, you can get the following result from the query below:
SELECT FriendName, SportName
FROM tblFriend
INNER JOIN tblSport
ON tblFriend.LikesSportID = tblSport.SportID
Man, it's late - I hope I got that right. by the way, you should read up on the different types of Joins - this is the simplest example of one.