I have an oracle database table with a lot of columns. I'd like to count the number of fully unique rows. The only thing I could find is:
SELECT COUNT(DISTINCT col_name) FROM table;
This however would require me listing all the columns and I haven't been able to come up with syntax that will do that for me. I'm guessing the reason for that is that this query would be very low performance? Is there a recommended way of doing this?
How about
SELECT COUNT(*)
FROM (SELECT DISTINCT * FROM Table)
It depends on what you are trying to accomplish.
To get a count of the distinct rows by specific column, so that you know what data exists, and how many of that distinct data there are:
SELECT DISTINCT
A_CODE, COUNT(*)
FROM MY_ARCHV
GROUP BY A_CODE
--This informs me there are 93 unique codes, and how many of each of those codes there are.
Another method
--How to count how many of a type value exists in an oracle table:
select A_CDE, --the value you need to count
count(*) as numInstances --how many of each value
from A_ARCH -- the table where it resides
group by A_CDE -- sorting method
Either way, you get something that looks like this:
A_CODE Count(*)
1603 32
1600 2
1605 14
I think you want a count of all distinct rows from a table like this
select count(1) as c
from (
select distinct *
from tbl
) distinct_tbl;
SELECT DISTINCT **col_name**, count(*) FROM **table_name** group by **col_name**
Related
fairly new to PostgreSQL and trying out a few count queries. I'm looking to count and count distinct all values in a table. Pretty straightforward -
CountD Count
351 400
With a query like this:
SELECT COUNT(*)
COUNT(id) AS count_id,
COUNT DISTINCT(id) AS count_d_id
FROM table
I see that I can create a single column this way:
SELECT COUNT(*) FROM (SELECT DISTINCT id FROM table) AS count_d_id
But the title (count_d_id) doesn't come through properly and unsure how can I add an additional column. Guidance appreciated
This is the correct syntax:
SELECT COUNT(id) AS count_id,
COUNT(DISTINCT id) AS count_d_id
FROM table
Your original query aliases the subquery rather than the column. You seem to want:
SELECT COUNT(*) AS count_d_id FROM (SELECT DISTINCT id FROM table) t
-- column alias --^ -- subquery alias --^
I need to sum the result of count of a column in one query.
Is it possible to have like this query?
SELECT sum(count(pro_id)) from jalasat group by pro_id
You have not mentioned which SQL database you are using so you may modify this slightly to fit it to what you are using:
SELECT SUM(cnt) FROM (SELECT COUNT(pro_id) as cnt
FROM jalasat
GROUP BY continent) as t1
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
If i perform a standard query in SQLite:
SELECT * FROM my_table
I get all records in my table as expected. If i perform following query:
SELECT *, 1 FROM my_table
I get all records as expected with rightmost column holding '1' in all records. But if i perform the query:
SELECT *, COUNT(*) FROM my_table
I get only ONE row (with rightmost column is a correct count).
Why is such results? I'm not very good in SQL, maybe such behavior is expected? It seems very strange and unlogical to me :(.
SELECT *, COUNT(*) FROM my_table is not what you want, and it's not really valid SQL, you have to group by all the columns that's not an aggregate.
You'd want something like
SELECT somecolumn,someothercolumn, COUNT(*)
FROM my_table
GROUP BY somecolumn,someothercolumn
If you want to count the number of records in your table, simply run:
SELECT COUNT(*) FROM your_table;
count(*) is an aggregate function. Aggregate functions need to be grouped for a meaningful results. You can read: count columns group by
If what you want is the total number of records in the table appended to each row you can do something like
SELECT *
FROM my_table
CROSS JOIN (SELECT COUNT(*) AS COUNT_OF_RECS_IN_MY_TABLE
FROM MY_TABLE)
I'm not sure if this is even a good question or not.
I have a complex query with lot's of unions that searches multiple tables for a certain keyword (user input). All tables in which there is searched are related to the table book.
There is paging on the resultset using LIMIT, so there's always a maximum of 10 results that get withdrawn.
I want an extra column in the resultset displaying the total amount of results found however. I do not want to do this using a separate query. Is it possible to add a count() column to the resultset that counts every result found?
the output would look like this:
ID Title Author Count(...)
1 book_1 auth_1 23
2 book_2 auth_2 23
4 book_4 auth_.. 23
...
Thanks!
This won't add the count to each row, but one way to get the total count without running a second query is to run your first query using the SQL_CALC_FOUND_ROWS option and then select FOUND_ROWS(). This is sometimes useful if you want to know how many total results there are so you can calculate the page count.
Example:
select SQL_CALC_FOUND_ROWS ID, Title, Author
from yourtable
limit 0, 10;
SELECT FOUND_ROWS();
From the manual:
http://dev.mysql.com/doc/refman/5.1/en/information-functions.html#function_found-rows
The usual way of counting in a query is to group on the fields that are returned:
select ID, Title, Author, count(*) as Cnt
from ...
group by ID, Title, Author
order by Title
limit 1, 10
The Cnt column will contain the number of records in each group, i.e. for each title.
Regarding second query:
select tbl.id, tbl.title, tbl.author, x.cnt
from tbl
cross join (select count(*) as cnt from tbl) as x
If you will not join to other table(s):
select tbl.id, tbl.title, tbl.author, x.cnt
from tbl, (select count(*) as cnt from tbl) as x
My Solution:
SELECT COUNT(1) over(partition BY text) totalRecordNumber
FROM (SELECT 'a' text, id_consult_req
FROM consult_req cr);
If your problem is simply the speed/cost of doing a second (complex) query I would suggest you simply select the resultset into a hash-table and then count the rows from there while returning, or even more efficiently use the rowcount of the previous resultset, then you do not even have to recount
This will add the total count on each row:
select count(*) over (order by (select 1)) as Cnt,*
from yourtable
Here is your answare:
SELECT *, #cnt count_rows FROM (
SELECT *, (#cnt := #cnt + 1) row_number FROM your_table
CROSS JOIN (SELECT #cnt := 0 AS variable) t
) t;
You simply cannot do this, you'll have to use a second query.