To Detecting duplicated rows in my table i have this query :
select SeatForShowtimeID_FK,count(*) as cnt from dbo.TicketRow
group by SeatForShowtimeID_FK
having cnt>1
I want to find row that have same SeatForShowtimeID_FK, but when i execute this query i get this error :
Invalid column name 'cnt'.
What should i do for this?
change having cnt > 1 to having count(*) > 1
HAVING clause is WHERE clause of GROUP BY.
In HAVING you can't use alias of field.
You have written:
having cnt>1
but cnt is an alias. Your condition must be COUNT(*)>1 (or COUNT(1) as suggested by Moho).
Related
I am trying to find the count of obsv_dt which has less than million records
select obsv_dt,count(*) as c from table
group by obsv_dt
having c<1000000
order by c
is giving unable to resolve column 'c'. I get that 'c' is alias and this error is expected
How can i get this working?
select obsv_dt,count(*) as c from table
group by obsv_dt
having count(*) <1000000
order by count(*)
You cannot use the alias before it has been calculated; try:
select
obsv_dt,
count(obsv_dt) as c
from
table
group by obsv_dt
having count(obsv_dt) < 1000000
order by count(obsv_dt)
There is a subtle difference in using count(*) vs count(col). But often it does not matter. count(*) vs count(column-name) - which is more correct?
Below is the precedence of sql clauses:
FROM clause
ON clause
OUTER clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
DISTINCT clause
ORDER BY clause
TOP clause
Since HAVING clause is evaluated prior to the SELECT clause it is
unware of the aliases. Similarly for all clauses except for ORDER BY
where we can include the alias for sorting the result set.
What if a SQL code as below?
Proc SQL;
SELECT DISTINCT ID,SUM(AMOUNT) AS M,SUM(NO) AS CNT
FROM CUSTOMER_LIST
GROUP BY ID
ORDER BY CNT DESC;
QUIT;
Use DISTINCT with GROUP BY. Any possible error will occur when using this combination Or DISTINCT just a redundant word?
Thanks~
Use DISTINCT with GROUP BY. Any possible error will occur when using this combination? Or DISTINCT just a redundant word?
This won't error, but that's just unnecessary redondancy. GROUP BY ID guarantees that each ID will appear only on one row in the resulset. There is no benefit for adding DISTINCT here - and it makes the intent of the query harder to understand.
On the other hand, there are situations where you would use DISTINCT without GROUP BY: typically when you want to deduplicate a set of columns, but do not need to use aggregate functions (SUM(), COUNT()...).
SELECT ID,SUM(AMOUNT) AS M,SUM(NO) AS CNT
FROM CUSTOMER_LIST
GROUP BY ID
ORDER BY CNT DESC;
We already group by id so no need distinct id
I am trying to run the query to get the total number of repetitions (appeared more than once) for one column called "abc" . I am trying this but not able to achieve.
select COUNT(SELECT DISTINCT card_no, COUNT(*) AS cnt )
please help, thanks in advance.
For Example below is the column :
cards
123,
456
,123
Result:
Count
1
As 123 appeared more than once.
You want the number of distinct values in the column that are repeated at least once, is that right?
SELECT COUNT(dupes)
FROM (SELECT card_no AS dupes, COUNT(*) cnt FROM table_name
GROUP BY card_no HAVING COUNT(*) > 1) A
Edit for explanation.
The inner query SELECT card_no AS dupes, COUNT(*) cnt FROM table_name GROUP BY card_no HAVING COUNT(*) > 1 returns only those values that are repeated in your table. The aliases on the columns are necessary because it's a subquery. You can run this query independently of the outer query to see what results it returns.
You have to have the group by on any field that you don't want to aggregate when you're aggregating other fields (e.g. performing a count of records), and the HAVING part is to filter out anything that isn't duplicated (i.e. has a count of 1). HAVING is the way to apply filtering on aggregated fields that you can't have in a WHERE.
The outer query SELECT COUNT(dupes)... is merely counting the number of card_no values returned by the inner query. Since these are grouped, it gives the number of distinct values that are duplicated.
A at the end there sets up an alias for the subquery so that it can be referenced like it's an actual table elsewhere in the query. This is necessary for any subquery in the FROM clause of another query. Effectively the select in the outer query reads SELECT COUNT(A.dupes)... and without the alias A there would be no way to qualify where the dupes field is being referenced from (even though in this case it's implied).
It's also worth noting that the field COUNT(*) cnt isn't required in the SELECT part of the subquery as it isn't being used anywhere else in the query. It will work just as effectively without it, as long as you still have the GROUP BY and HAVING clauses.
SELECT
card_no, COUNT(*) AS "Occurrences"
FROM
YourTable
GROUP BY card_no
HAVING
COUNT(*) > 1
I have a simple query in a tabloid control that gets all the leads in one month. I then use the tabloid control to group them into lead source. And then I have an associated count column. I want to sort my report on the count descending, without doing it in the query. I keep getting an error saying you cannot sort on an aggregate.
Thanks.
you can do one more thing..
just write your query in subquery part and write order by clause in outer query.
(suppose you have group by query as follow-
select lead_source, count(*) cnt
from your_table
group by lead_source
)
so you can do as follow -
select lead_source, cnt from (
select lead_source, count(*) cnt
from your_table
group by lead_source
)
order by cnt
this your_table and group by column list you have to edit accordingly your table structure ..
Looking for sql to get distinct names and count of those names from a sql table:
Structure:
id
name
other details
Do I use distinct to get each group and then count through those to get:
name1 count(name1)
name2 count(name2)
etc
Thanks
Rob.
When you want a COUNT() or a SUM(), you're using an AGGREGATE FUNCTION based on a GROUP BY clause.
As GROUP BY brings together all records with the same values specified in the GROUP BY columns, you're already getting the same effect as DISTINCT.
Except that DISTINCT doesn't allow aggregates, and GROUP BY does.
SELECT
name,
COUNT(*) AS count_of_name
FROM
yourTable
GROUP BY
name
Try :
SELECT *, COUNT(*) FROM my_table GROUP BY name
Something like this?
select name,COUNT(name) FROM Persons GROUP BY name
In the end I used:
SELECT DISTINCT `school`,COUNT(`school`) AS cat_num FROM table GROUP BY school order by cat_num DESC