Using SQL Server 2014. Taking the following recordset:
I need to find a way to extract the ordOrderNum which is duplicates, with a different DeliveryNum. In this example, orders 93400460 and 93400467 would be extract, because they are duplicates. Order 93408170 is ok. How can I do that??!
thanks for your time and help
You can use group by and having:
select ordOrderNum
from mytable
group by ordOrderNum
having min(ordDeliveryNum) <> max(ordDeliveryNum)
Try this:
SELECT
ORDORDERNUM, ORDLINENUM,
COUNT(*) FROM TABLE
GROUP BY
ORDORDERNUM, ORDLINENUM
Having count(*)>1
Related
I need to know where the mistake is in this oracle query?
SELECT(KEY1),COUNT(*) FROM TABLE1 GROUP BY AGE
SELECT KEY1,COUNT(*) FROM TABLE1 GROUP BY KEY1
There are two problems. First one: You cannot close the parenthesis after the first keyword. Second: You have to group by all keys that are in the query that are not all row dependend. In that case "KEY1". If you want to order by age you have to query age as parameter.
SELECT AGE,COUNT(*) FROM TABLE1 GROUP BY AGE
Your table naming is not very good. I assume you should have a look at group by tutorials like https://www.w3schools.com/sql/sql_groupby.asp or the sql tutorial https://www.w3schools.com/sql/
Your query had an issue. You have to modify your query as below
SELECT KEY1,COUNT(*) FROM TABLE1 GROUP BY KEY1.
Observation:
All the columns that are added in the select statement alongside the aggregate functions, should be included the group by columns.
Your first column does have the bracket in it which should be removed.
I am trying to use group by with count function but this doesn't work.
SELECT
projects.AgencyId,
projects.ProgramId,
count(projects.ProjStatusByMin) as status,
projects.ProjStatusByMin
from
projects
where
projects.AgencyId=40
group by
projects.ProjStatusByMin
This above code works in MySQL perfectly now i want to achieve the same thing in SQL Server.
Select
ProjStatusByMin,
COUNT(ProjStatusByMin) [projstatus]
from
Projects
where
AgencyId=40
group by
ProjStatusByMin,AgencyId,ProjId
However if i select a single column like the bellow code then group by work
Select
ProjStatusByMin,
COUNT(ProjStatusByMin) [projstatus]
from
Projects
where
AgencyId=40
group by
ProjStatusByMin
Now how can I achieve group by with multi column selected?
You have to add all the columns (except for the one in the count function) to the group by clause.
SELECT projects.AgencyId,projects.ProgramId,count(projects.ProjStatusByMin) as status,
projects.ProjStatusByMin
from projects
where projects.AgencyId=40
group by projects.ProjStatusByMin, projects.AgencyId,projects.ProgramId
In Sql Server you have to write all the column names in group by clause which you are going to select in the select statement.
I am using an SQL query with of form
SELECT...FROM...WHERE...GROUP BY id
I want to know how many groups this query returns. How to do this?
SELECT count(id) FROM....WHERE...GROUP BY id
#Tyler Ferraro answers should solve it.
In case the SQL query is very complicated, you can use a nested query:
SELECT COUNT(*) FROM (SELECT...FROM...WHERE...GROUP BY id)
Try this:
select count(*) from (Your SQL).
According to tips from MySQL performance wiki:
Don't use DISTINCT when you have or could use GROUP BY.
Can somebody post example of queries where GROUP BY can be used instead of DISTINCT?
If you know that two columns from your result are always directly related then it's slower to do this:
SELECT DISTINCT CustomerId, CustomerName FROM (...)
than this:
SELECT CustomerId, CustomerName FROM (...) GROUP BY CustomerId
because in the second case it only has to compare the id, but in the first case it has to compare both fields. This is a MySQL specific trick. It won't work with other databases.
SELECT Code
FROM YourTable
GROUP BY Code
vs
SELECT DISTINCT Code
FROM YourTable
The basic rule : Put all the columns from the SELECT clause into the GROUP BY clause
so
SELECT DISTINCT a,b,c FROM D
becomes
SELECT a,b,c FROM D GROUP BY a,b,c
Example.
Relation customer(ssnum,name, zipcode, address) PK(ssnum). ssnum is social security number.
SQL:
Select DISTINCT ssnum from customer where zipcode=1234 group by name
This SQL statement returns unique records for those customer's that have zipcode 1234. At the end results are grouped by name.
Here DISTINCT is no not necessary. because you are selecting ssnum which is already unique because ssnun is primary key. two person can not have same ssnum.
In this case Select ssnum from customer where zipcode=1234 group by name will give better performance than "... DISTINCT.......".
DISTINCT is an expensive operation in a DBMS.
Given a command in SQL;
SELECT ...
FROM ...
GROUP BY ...
Can I group by something that isn't in the SELECT line?
Yes.
This is often used in the superaggregate queries like this:
SELECT AVG(cnt)
FROM (
SELECT COUNT(*) AS cnt
FROM sales
GROUP BY
product
HAVING COUNT(*) > 10
) q
, which aggregate the aggregates.
Yes of course e.g.
select
count(*)
from
some_table_with_updated_column
group by
trunc(updated, 'MM.YYYY')
Yes you can do it, but if you do that you won't be able to tell which result is for which group.
As a result, you almost always want to return the columns you've grouped by in the select clause. But you don't have to.
Yes, you can. Example:
select count(1)
from sales
group by salesman_id
What you can't do, of course, if having something on your select clause (other than aggregate functions) that are not part of the group by clause.
Hmm, I think the question should have been in the other way round like,
Can I SELECT something that is not there in the GROUP BY?
It's alright to write a code like:
SELECT customerId, count(orderId) FROM orders
GROUP BY customerId, orderedOn
If you want to find out the number of orders done by a customer datewise.
But you cannot do it the other way round:
SELECT customerId, orderedOn count(orderId) FROM orders
GROUP BY customerId
You can issue an aggregate function on the column that is not there in the group by. But you cannot give it in the select line without the aggregate function. As it will not make much sense. Like for the above query. You group by just customerId for order counts and you want the date also to be printed in the output??!! You don't involve the date factor in the group for counting then will it mean something to have a date in it?
I don't know about other DBMS' but DB2/z, for one, does this just fine. It's not required to have the column in the select portion but, of course, it does have to extract the data from the table in order to aggregate so you're probably not saving any time by leaving it off. You should only select the columns that you need, aggregation of the data is a separate task from that.
I'm pretty certain the SQL standard allows this (although that's only based on the knowledge that the mainframe DB2 product follows it pretty closely).