How can I count the occurrence of the field/column in SQL?
Example dataset:
A
A
A
A
B
B
C
I want:
A | 4
A | 4
A | 4
A | 4
B | 2
B | 2
C | 1
Is there anyway to do it without using GROUP BY? So far all answer I get my query retuns the following:
A | 4
B | 2
C | 1
select value, count(*) from table group by value
Use HAVING to further reduce the results, e.g. only values that occur more than 3 times:
select value, count(*) from table group by value having count(*) > 3
You could use a nested sub-select for this desired result set.
If the example table name is my_table and the column called col1:
select col1,
(select count(*) from my_table where col1 = t.col1) as Count
from my_table t;
Or if you want to remove the duplicates, use the distinct statement. It removes the duplicates of your result set.
select distinct col1,
(select count(*) from my_table where col1 = t.col1) as Count
from my_table t;
Related
I have a table with two sets of integer values. Using MySQL I want to display all of the rows that correspond to unique entries in the second column. Basically I can have duplicate A values, but only unique B values. If there are duplicates for a value in B, remove all the results with that value. If I use DISTINCT I will still get one of those duplicates which I do not want. I also want to avoid using COUNT(). Here's an example:
|_A____B_|
| 1 2 |
| 1 3 |
| 2 2 |
| 2 4 |
| 1 4 |
| 5 5 |
Will have the following Results (1,3), (5,5). Any value in B that has a duplicate is removed.
Try this
SELECT * FROM TEMP WHERE B IN (
SELECT B FROM TEMP GROUP BY B Having COUNT(B)=1
);
I know you want to avoid using COUNT() but this is the quick solution.
working fiddle here - http://sqlfiddle.com/#!9/29d16/8
Tested and works! you need atleast count(*) to count the values
select * from test where B in (
select B from test group by B having count(*)<2
)
I don't know why you want to avoid using count(), because that's what would do the trick as follows:
Let's say your table is named "mytable"
SELECT t1.A, t1.B
FROM mytable t1
JOIN (
SELECT B, count(*) AS B_INSTANCES
FROM mytable
GROUP BY B
HAVING count(*) = 1
) t2 ON t2.B = t1.B
ORDER BY t1.A, t1.B
I have different tables (per region) with some columns that are the same. Now I need to have a count for each value that is placed in one column over multiple tables. I'm trying to get a sum for this so I don't have to use 4 separate queries and outputs. Furthermore the values are matched with a lookup table
Region table(s) - Table1:
id | Column1 |
---------|----------|
1 | 1
2 | 2
3 | 3
etc
Lookup table
id | Description |
---------|-------------|
1 | Description1
2 | Description2
3 | Description3
The query I'm using to get the count from 1 of the tables is :
SELECT Description, Count(*) as Number from Table1, LookupTable
WHERE Column1 = LookupTable.id GROUP BY Column1 ORDER BY Number Desc
The output is
Description | Number
---------------|--------
Description1 | Number
Description2 | Number
Etc.
Any idea on how to sum up the counts for each Description/value of Column1 from 4 tables that generates the output as displayed above (but then with the sum value for each description)?
It's not clear but I guess you can use:
select LookupTable.id,LookupTable.Description, SUM(Cnt) as Number
from LookupTable
JOIN
(
SELECT Column1 as CId, count(*) as Cnt from Table1 group by Column1
union all
SELECT Column2 as CId, count(*) as Cnt from Table2 group by Column2
union all
SELECT Column3 as CId, count(*) as Cnt from Table3 group by Column3
union all
SELECT Column4 as CId, count(*) as Cnt from Table4 group by Column4
) T1 on LookupTable.id =T1.Cid
GROUP BY LookupTable.id,LookupTable.Description
ORDER BY Number Desc
Use this query:
SELECT LookupTable.Description, Count(*) as Number
FROM Table1, LookupTable
WHERE Table1.Column1 = LookupTable.id
GROUP BY Table1.Column1;
You have leave the name of table or its alias to call the column.
I have a table tbl_entries with the following structure:
+----+------+------+------+
| id | col1 | col2 | col3 |
+----+------+------+------+
| 11 | a | b | c |
| 12 | d | e | a |
| 13 | a | b | c |
| 14 | X | e | 2 |
| 15 | a | b | c |
+----+------+------+------+
And another table tbl_reviewlist with the following structure:
+----+-------+------+------+------+
| id | entid | cola | colb | colc |
+----+-------+------+------+------+
| 1 | 12 | N | Y | Y |
| 2 | 13 | Y | N | Y |
| 3 | 14 | Y | N | N |
+----+-------+------+------+------+
Basically, tbl_reviewlist contains reviews about the entries in tbl_entries. However, for some known reason, the entries in tbl_entries are duplicated. I am extracting the unique records by the following query:
SELECT * FROM `tbl_entries` GROUP BY `col1`, `col2`, `col3`;
However, any one of the duplicate rows from tbl_entries will be returned no matter they have been reviewed or not. I want the query to prefer those rows which have been reviewed. How can I do that?
EDIT: I want to prefer rows which have been reviewed but if there are rows which have not been reviewed yet it should return those as well.
Thanks in advance!
Have you actually tried anything?
A hint: The SQL standard requires that every column in the result set of a query with a group by clause must be either
a grouping column
an aggregate function — sum(), count(), etc.,
a constant value/literal, or
an expression derived solely from the above.
Some broken implementations (and I believe MySQL is one of them) allow other columns to be included and offer their own...creative...behavior. If you think about it, group by essentially says to do the following:
Order this table by the grouping expressions
Partition it into subsets based on the group by sequence
Collapse each such partition into a single row computing the aggregate expressions as you go.
Once you've done that, what does it mean to ask for something that isn't uniform across the collapsed group partition?
If you have a table foo containing columns A, B, C, D and E and say something like
select A,B,C,D,E from foo group by A,B,C
per the standard, you should get a compile error. Deviant implementations [usually] treat this sort of query as the [rough] equivalent of
select *
from foo t
join ( select A,B,C
from foo
group by A,B,C
) x on x.A = t.A
and x.B = t.B
and x.C = t.C
But I wouldn't necessarily count on that without review the documentation for the specific implementation that your are using.
If you want to find just reviewed entries, then something like this:
select *
from tbl_entries t
where exists ( select *
from tbl_reviewlist x
where x.entid = t.id
)
will do you. If, however, you want to find reviewed entries that are duplicated on col1, col2 and col3 then something like this should do you:
select *
from tbl_entries t
join ( select col1,col2,col3
from tbl_entries x
group by col1,col2,col3
having count(*) > 1
) d on d.col1 = t.col1
and d.col2 = t.col2
and d.col3 = t.col3
where exists ( select *
from tbl_reviewlist x
where x.entid = t.id
)
Since your problem statement is rather unclear, another take might be something along these lines:
select t.col1 ,
t.col2 ,
t.col3 ,
t.duplicate_count ,
coalesce(x.review_count,0) as review_count
from ( select col1 ,
col2 ,
col3 ,
count(*) as duplicate_count
from tbl_entries
group by col1 ,
col2 ,
col3
) t
left join ( select cola, colb, colc , count(*) as review_count
from tbl_reviewList
group by cola, colb, colc
having count(*) > 1
) x on x.cola = t.col1
and x.colb = t.col2
and x.colc = t.col3
order by sign(coalesce(x.review_count,0)) desc ,
t.col1 ,
t.col2 ,
t.col3
This query
summarizes the entries table, developing a count of how many time seach col1/2/3 combination exists.
summarizes the review table, developing a count of reviews for each cola/b/c combination
joins them together matching cols a:1, b:2 c:3
orders them
preferring reviewed items to non-reviewed items by placing them first,
then by the col1/2/3 values.
I think there's a way with less repetition, but this should be a start:
select
tbl_entries.ID,
col1,
col2,
col3,
cola, -- ... you get the idea ...
from (
select coalesce(min(entid), min(tbl_entries.ID)) as favID
from tbl_entries left join tbl_reviewlist on entid = tbl_entries.ID
group by col1, col2, col3
) as A join tbl_entries on tbl_entries.ID = favID
left join tbl_reviewlist on entid = tbl_entries.ID
Basically you distill the desired output to a list of core ID's and then re-map back to the data...
SELECT e.col1, e.col2, e.col3,
COALESCE(MIN(r.entid), MIN(e.id)) AS id
FROM tbl_entries AS e
LEFT JOIN tbl_reviewlist AS r
ON r.entid = e.id
GROUP BY e.col1, e.col2, e.col3 ;
Tested at SQL-Fiddle
Is it possible to select the next lower number from a table without using limit.
Eg: If my table had 10, 3, 2 , 1 I'm trying to select * from table where col > 10.
The result I'm expecting is 3. I know I can use limit 1, but can it be done without that?
Try
SELECT MAX(no) no
FROM table1
WHERE no < 10
Output:
| NO |
------
| 3 |
SQLFiddle
Try this query
SELECT
*
FROM
(SELECT
#rid:=#rid+1 as rId,
a.*
FROM
tbl a
JOIN
(SELECT #rid:=0) b
ORDER BY
id DESC)tmp
WHERE rId=2;
SQL FIDDLE:
| RID | ID | TYPE | DETAILS |
------------------------------------
| 2 | 28 | Twitter | #sqlfiddle5 |
Another approach
select a.* from supportContacts a inner join
(select max(id) as id
from supportContacts
where
id in (select id from supportContacts where id not in
(select max(id) from supportContacts)))b
on a.id=b.id
SQL FIDDLE:
| ID | TYPE | DETAILS |
------------------------------
| 28 | Twitter | #sqlfiddle5 |
Alternatively, this query will always get the second highest number based on the inner where clause.
SELECT *
FROM
(
SELECT t.col,
(
SELECT COUNT(distinct t2.col)
FROM tableName t2
WHERE t2.col >= t.col
) as rank
FROM tablename t
WHERE col <= 10
) xx
WHERE rank = 2 -- <<== means second highest
SQLFiddle Demo
SQLFiddle Demo (supports duplicate values)
If you want to get next lower number from table
you can get it with this query:
SELECT distinct col FROM table1 a
WHERE 2 = (SELECT count(DISTINCT(b.col)) FROM table1 b WHERE a.col >= b.col);
later again if you want to get third lower number you can just pass 3 in place of 2 in where clause
again if you want to get second higher number, just change the condition of where clause in inner query with
a.col <= b.col
Hi there m trying to calculate the row count for same value,
id,value
1 | a
2 | b
3 | c
4 | d
5 | e
and my query is
select value, count(*) as Count from mytable where id in('4','2','4','1','4') group by value having count(*) > 1
for which my expected output will be,
value,Count
d | 3
b | 1
a | 1
Thanks, any help will be appreciated
Try that:
SELECT value, count(value) AS Count
FROM mytable m
WHERE value = m.value
GROUP BY value
SELECT t.id, t.value, COUNT(t.id)
FROM
test t
JOIN
( SELECT 1 AS id
UNION ALL SELECT 3
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 1
UNION ALL SELECT 1 ) AS tmp
ON t.id = tmp.id
GROUP BY t.id
Sample on sqlfiddle.com
See also: Force MySQL to return duplicates from WHERE IN clause without using JOIN/UNION?
Of course, your IN parameter will be dynamic, and thus you will have to generate the corresponding SQL statement for the tmp table.
That's the SQL-only way to do it. Another possibility is to have the query like you have it in your question and afterwards programmatically associate the rows to the count passed to the IN parameter.