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
Related
Is there an easy way avoiding the usage of cursors to convert this:
+-------+------+-------+
| Group | From | Until |
+-------+------+-------+
| X | 1 | 3 |
+-------+------+-------+
| X | 2 | 4 |
+-------+------+-------+
| Y | 5 | 7 |
+-------+------+-------+
| X | 8 | 10 |
+-------+------+-------+
| Y | 11 | 12 |
+-------+------+-------+
| Y | 12 | 13 |
+-------+------+-------+
Into this:
+-------+------+-------+
| Group | From | Until |
+-------+------+-------+
| X | 1 | 4 |
+-------+------+-------+
| Y | 5 | 7 |
+-------+------+-------+
| X | 8 | 10 |
+-------+------+-------+
| Y | 11 | 13 |
+-------+------+-------+
So far I've tried to assign an ID to each row and GROUP BY that ID, but I can't get any closer without using cursors.
SELECT `Group`, `From`, `Until`
FROM ( SELECT `Group`, `From`, ROW_NUMBER() OVER (PARTITION BY `Group` ORDER BY `From`) rn
FROM test t1
WHERE NOT EXISTS ( SELECT NULL
FROM test t2
WHERE t1.`From` > t2.`From`
AND t1.`From` <= t2.`Until`
AND t1.`Group` = t2.`Group` ) ) t3
JOIN ( SELECT `Group`, `Until`, ROW_NUMBER() OVER (PARTITION BY `Group` ORDER BY `From`) rn
FROM test t1
WHERE NOT EXISTS ( SELECT NULL
FROM test t2
WHERE t1.`Until` >= t2.`From`
AND t1.`Until` < t2.`Until`
AND t1.`Group` = t2.`Group` ) ) t4 USING (`Group`, rn)
fiddle
Must work at any overlapping type (partially overlapped, adjacent, fully included).
Will not work if From and/or Until is NULL.
Could you add an explanation in English? – ysth
1st subquery searches joined ranges starts (see the fiddle - it is executed separately) - it searches for From value in a group which is not in the middle/end of any other range (start point equiality allowed).
2nd subquery do the same for joined ranges Until.
Both additionally enumerates found values ascending.
Outer query simply joins each range start and its finish into one row.
If you are using MYSQL version 8+ then you can use row_number to get the desired result:
Demo
SELECT MIN(`FROM`) START,
MAX(`UNTIL`) END,
`GROUP` FROM (
SELECT A.*,
ROW_NUMBER() OVER(ORDER BY `FROM`) RN_FROM,
ROW_NUMBER() OVER(PARTITION BY `GROUP` ORDER BY `UNTIL`) RN_UNTIL
FROM Table_lag A) X
GROUP BY `GROUP`, (RN_FROM - RN_UNTIL)
ORDER BY START;
You can do this with window functions only, using some gaps-and-island technique.
The idea is to build group of consecutive record having the same group and overlapping ranges, using lag() and a window sum(). You can then aggregate the groups:
select grp, min(c_from) c_from, max(c_until) c_until
from (
select
t.*,
sum(lag_c_until < c_from) over(partition by grp order by c_from) mygrp
from (
select
t.*,
lag(c_until, 1, c_until) over(partition by grp order by c_from) lag_c_until
from mytable t
) t
) t
group by grp, mygrp
The column names you chose conflict with SQL keywords (group, from), so I renamed them to grp, c_from and c_until.
Demo on DB Fiddle - with credits to ysth for creating the fiddle in the first place:
grp | c_from | c_until
:-- | -----: | ------:
X | 1 | 4
Y | 5 | 7
X | 8 | 10
Y | 11 | 13
I would use a recursive CTE for this:
with recursive intervals (`Group`, `From`, `Until`) as (
select distinct t1.Group, t1.From, t1.Until
from Table_lag t1
where not exists (
select 1
from Table_lag t2
where t1.Group=t2.Group
and t1.From between t2.From and t2.Until+1
and (t1.From,t1.Until) <> (t2.From,t2.Until)
)
union all
select t1.Group, t1.From, t2.Until
from intervals t1
join Table_lag t2
on t2.Group=t1.Group
and t2.From between t1.From and t1.Until+1
and t2.Until > t1.Until
)
select `Group`, `From`, max(`Until`) as Until
from intervals
group by `Group`, `From`
order by `From`, `Group`;
The anchor expression (select .. where not exists (...)) finds all the group & from that won't combine with some earlier from (so has one row for each row in our eventual output):
Then the recursive query adds rows for merged intervals for each of our rows.
Then just group by group and from (those are awful column names) to get the biggest
interval for each starting group/from.
https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=9efa508504b80e44b73c952572394b76
Alternatively, you can do it with a straightforward set of joins and subqueries, with no CTE or window functions needed:
select
interval_start_range.grp,
interval_start_range.start,
max(merged.finish) finish
from (
select
interval_start.grp,
interval_start.start,
min(later_interval_start.start) next_start
from (
select distinct t1.grp, t1.start, t1.finish
from Table_lag t1
where not exists (
select 1
from Table_lag t2
where t1.grp=t2.grp
and t1.start between t2.start and t2.finish+1
and (t1.start,t1.finish) <> (t2.start,t2.finish)
)
) interval_start
left join (
select distinct t1.grp, t1.start, t1.finish
from Table_lag t1
where not exists (
select 1
from Table_lag t2
where t1.grp=t2.grp
and t1.start between t2.start and t2.finish+1
and (t1.start,t1.finish) <> (t2.start,t2.finish)
)
) later_interval_start
on interval_start.grp=later_interval_start.grp
and interval_start.start < later_interval_start.start
group by interval_start.grp, interval_start.start
) as interval_start_range
join Table_lag merged
on merged.grp=interval_start_range.grp
and merged.start >= interval_start_range.start
and (interval_start_range.next_start is null or merged.start < interval_start_range.next_start)
group by interval_start_range.grp, interval_start_range.start
order by interval_start_range.start, interval_start_range.grp
(I have renamed the columns here to not need backticks.)
Here there's a select to get all the starts of the reportable intervals we will report, joined to another similar select (you could use a CTE to avoid the redundancy) to find the following start of a reportable interval for the same group (if there is one). That's wrapped in a subquery to get the group, the start value, and the start value of the following reportable interval. Then it just needs to join all the other records that start within that range and pick the maximum ending value.
https://dbfiddle.uk/?rdbms=mysql_5.5&fiddle=151cc933489c299f7beefa99e1959549
table one
+----------------------+
|column A | Column B|
| 2 | 4 |
| 3 | 5 |
| 1 | 2 |
| 1 | 2 |
| 8 | 7 |
+----------------------+
Output
+-------+
|1 | 2 |
|1 | 2 |
+-------+
i want to print only the above output without COUNT, and any duplicate record example? please help
how about below where cluase
select * from t where columnA=1 and columnB=2
or
select columnA,columnB from t
group by columnA,columnB
having count(*)>1
or you can use exists
select t1.* from t t1 where exists
(select 1 from t t2 where t2.columnA=t1.columnA
and t2.columnB=t1.columnB group by columnA,columnB
having count(*)>1
)
You possibly want only those rows which are duplicate. If you don't have Window Functions available in your MySQL version, you can do the following:
SELECT
t.*
FROM your_table AS t
JOIN (SELECT columnA, columnB
FROM your_table
GROUP BY columnA, columnB
HAVING COUNT(*) > 1) AS dt
ON dt.columnA = t.columnA AND dt.columnB = t.columnB
Details: In a Derived table, we get all those combination of columnA and columnB which have more than one row(s) (HAVING COUNT(*) > 1).
Now, we simply join this result-set back to the main table, to get those rows only.
Note: This approach would not be needed if you want to fetch only these two columns. A simple Group By with Having would suffice, as suggested in other answer(s). However, if you have more columns in the table, and you will need to fetch all of them, and not just the columns (used to determine duplicates); you will need to use this approach.
You can use in operator with a grouped subquery as :
select *
from tab
where ( columnA, columnB) in
(
select columnA, count(columnA)
from tab
group by columnA
);
or use a self-join as :
select t1.columnA, t1.columnB
from tab t1
join
(
select columnA, count(columnA) as columnB
from tab
group by columnA
) t2
on ( t1.columnA = t2.columnA and t1.columnB = t2.columnB );
Rextester Demo
I would use EXISTS, if the table has primary column :
SELECT t.*
FROM table t
WHERE EXISTS (SELECT 1 FROM table t1 WHERE t1.col1 = t.col1 AND t1.col2 = t.col2 AND t1.pk <> t.pk);
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;
I have a table like this in MYSQL:
ID | NAME | VALUE |
----------------------------
1 | Bob | 1 |
2 | Bob | 2 |
3 | Jack | 5 |
4 | Jack | 8 |
5 | Jack | 10 |
and I'm trying to update the VALUE column to the highest value of rows with same NAME. So the result should be:
ID | NAME | VALUE |
----------------------------
1 | Bob | 2 |
2 | Bob | 2 |
3 | Jack | 10 |
4 | Jack | 10 |
5 | Jack | 10 |
I managed to get the max value like this:
SELECT MAX(Value) max FROM `table` GROUP BY Name having count(*) >1 AND MAX(Value) != MIN(Value)
But can't figure out how to put it in my update
Update table set Value = (SELECT MAX(Value) max FROM `table` GROUP BY Name having count(*) >1 AND MAX(Value) != MIN(Value))
Doesn't work. I'd appreciate any help.
This is easier than other answers are making it.
UPDATE MyTable AS t1 INNER JOIN MyTable AS t2 USING (Name)
SET Value = GREATEST(t1.Value, t2.Value);
You don't have to find the largest value. You just have to join each row to the set of rows with the same name, and set the Value to the greater Value of the two joined rows. This is a no-op on some rows, but it will apply to every row in turn.
http://sqlfiddle.com/#!9/f79a3/1
UPDATE t1
INNER JOIN (SELECT name, MAX(`value`) max_value
FROM t1 GROUP BY name) t2
ON t1.name = t2.name
SET t1.value = t2.max_value;
Create a temporary table consisting of ID NAME and MAX VALUE as follows:
CREATE TEMP TABLE TABLE1 AS
(SELECT NAME,MAX(Value) value FROM `table` GROUP BY Name having count(*) >1
AND MAX(Value) != MIN(Value)
);
Use this temporary table to do your update as follows:
UPDATE
Table_A
SET
Table_A.value = Table_B.value
FROM
`table` AS Table_A
INNER JOIN TABLE1 AS Table_B
ON Table_A.NAME = Table_B.NAME
Also this code is somewhat of an approximation as i am not familiar with mysql but i am familiar with sql.
Let me know if this doesn't help.
Simple left join would do the trick.
Try this out and let me know in case of any queries.
select a.id,a.name,b.value
from
table a
left join
(select name,max(value) as value from table group by name) b
on a.name=b.name;
You may use this query. The table is joined with a subquery (table t2) that contains the results you want to update your table with:
UPDATE `table` t1,
(SELECT Name, MAX(Value) maxv, MIN(Value) minv
FROM `table`
GROUP BY Name
HAVING COUNT(*)>1 AND maxv != minv) t2
SET t1.Value = t2.maxv
WHERE t1.Name = t2.Name;
If you want to know how will the values be updated, you can first run an equivalent SELECT query:
SELECT t1.*, t2.maxv
FROM `table` t1,
(SELECT Name, MAX(Value) maxv, MIN(Value) minv
FROM `table`
GROUP BY Name
HAVING COUNT(*)>1 AND maxv != minv) t2
WHERE t1.Name = t2.Name;
This query will display all the fields of table, followed by the new value maxv. You can check the current value and the new value, and if it looks fine, you may run the UPDATE query.
I have the next table:
+---------+------------+
| firm_id | service_id |
+---------+------------+
| 6 | 2 |
| 6 | 4 |
| 23 | 7 |
| 23 | 6 |
I want to get ONLY companies who do not have service_id=4 in their service list.
A query of the above table should return only the company with firm_id=23 because firm_id=6 has one record with service_id=4.
I want to make it with one query. Is this possible (without joins)?
Thanks.
P.S. Thanks everyone. User "derobert" suggested very interesting way, what i was looking for.
You can do it several ways. Here is one, with a correlated subquery:
SELECT DISTINCT firm_id FROM table t1
WHERE NOT EXISTS ( SELECT 1 FROM table t2 WHERE t1.firm_id = t2.firm_id AND t2.service_id = 4)
In MySQL-land it is often better to rewrite as a self-join:
SELECT DISTINCT firm_id
FROM table t1 LEFT JOIN table t2 ON (t1.firm_id = t2.firm_id AND t2.service_id = 4)
WHERE t2.firm_id IS NULL
Finally, here is one way to do it that doesn't involve subqueries or joins (but I expect performs worse than either of the above)
SELECT firm_id, CONCAT(',', GROUP_CONCAT(service_id SEPARATOR ','), ',') AS service_ids
FROM table t1
GROUP BY firm_id
HAVING service_ids NOT LIKE '%,4,%'
I confess I haven't actually run these; please forgive typos.
SELECT DISTINCT
firm_id
FROM
TableX AS t
WHERE
NOT EXISTS
( SELECT
*
FROM
TableX AS s
WHERE
s.firm_id = t.firm_id
AND
s.service_id = 4
)
or:
SELECT
firm_id
FROM
TableX
GROUP BY
firm_id
HAVING
COUNT(service_id = 4) = 0
You could try
SELECT * FROM your_table
WHERE firm_id NOT IN
(SELECT DISTINCT firm_id FROM your_table
WHERE service_id = 4) a
As suggested by ypercube (thanks!) you can also try
SELECT DISTINCT firm_id, service_id FROM your_table
WHERE firm_id NOT IN
(SELECT firm_id FROM your_table
WHERE service_id = 4) a