I need to update the current row using the following logic:
if current row is null, then set it as previous row
if current row is not null, then no action
the 1st row is not null, then NULL appears randomly
Those NULLs need to be updated using the logic previously mentioned
e.g.
1. 1
2. null
3. null
4. 2
5. null
6. null
needs to be updated as
1. 1
2. 1
3. 1
4. 2
5. 2
6. 2
How to do it in SQL?
Thanks
r
In case of two Null values in a row, you need to define the least non-null value of the table, so I think Outer Apply will handle your problem:
CREATE TABLE #TB(ID Int Identity(1, 1), Value Int)
INSERT INTO #TB([Value]) VALUES(1),(Null),(Null),(2),(Null),(Null)
UPDATE G SET G.Value = GG.Value
FROM
#TB AS G
OUTER APPLY
(SELECT
TOP 1 *
FROM
#TB AS GG
WHERE
GG.Value IS NOT NULL
AND
GG.ID < G.ID
ORDER BY
GG.ID DESC
) AS GG
WHERE
G.Value IS NULL
SELECT * FROM #TB AS T
but note, that if the first value is Null it will not give you the results, as you have not defined the logic for this scenario.
This might help:
SELECT
t1.col1,
t1.col2 AS previous,
(SELECT
t2.col2
FROM table_1 t2
WHERE t2.col1 = (SELECT
MAX(t3.col1)
FROM table_1 t3
WHERE t3.col1 <= t1.col1
AND col2 IS NOT NULL))
AS new
FROM table_1 t1;
result
Where are you using this SQL code? If you are using Hive SQL for example, there is a function which allows you to directly get last non null value:
LAST_VALUE(col, true) over (PARTITION BY id ORDER BY date)
Oracle 10g has also a function to do this, as adressed in this thread:
Fill null values with last non-null amount - Oracle SQL
Are you familiar with window functions?
while (select count(*) FROM Table_1 where c1_derived = '') > 0
begin
update top(1) Table_1
set c1_derived = (select c1_derived from Table_1 t2 where (t2.id = [Table_1].id-1))
where c1_derived = ''
end
Try the below script. (sql 2008 +)
CREATE TABLE #table(id Int Identity(1, 1), value Int)
INSERT INTO #table([Value]) VALUES(1),(Null),(Null),(2),(Null),(Null)
;WITH cte AS
(
SELECT ID,Value,ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS row
FROM #table
)
SELECT a.ID,max(b.Value)
FROM cte a
INNER JOIN cte b ON a.row >=b.row
GROUP BY a.ID
drop table #table
Edit2 this also another script using "UNBOUNDED PRECEDING "
CREATE TABLE #table(id Int Identity(1, 1), value Int)
INSERT INTO #table([Value]) VALUES(1),(Null),(Null),(2),(Null),(Null)
select * ,max(t.value) over(order by Id Rows UNBOUNDED PRECEDING) maxValue
from #table t
drop table #table
check this link about "OVER Clause"
https://learn.microsoft.com/en-us/sql/t-sql/queries/select-over-clause-transact-sql
Related
Have a scenario to select the value from table where range condition is present in source table.
Like,
TableA
ID value condition
1 20 A-M
2 50 N-Z
Select value from TableA where condition = 'C%'
--want to select TableA value from TableB by passing person name starts with like,
-- Here C is item name starts with
-- Should compare with range (A-M) and return first row.
-- Condition column is varchar(3)
I have seen the solution on other way where range can be compared with input value, but here the range is present in the source table. Please help.
If I have understood what you are after correctly you can use
SELECT TOP 1 B.*
FROM TableB B
WHERE B.Name LIKE (SELECT CONCAT('[',condition,']%') FROM TableA WHERE ID =1)
ORDER BY B.Id
If I understand correctly, you should be structuring TableA as:
ID value Lower Upper
1 20 A M
2 50 N Z
Then you want:
select a.*
from tableA a
where left(#name, 1) between a.lower and a.upper;
You can get this to work with your format, by doing:
select a.*
from tableA a
where left(#name, 1) between left(a.condition) and right(a.condition);
But I don't recommend that. Better to store the condition in two columns.
I would use QUOTENAME() function as
SELECT *
FROM TableA
WHERE #Condition LIKE QUOTENAME(Condition);
This will be as
WHERE 'C' LIKE [A-M] --return True
Demo1
Demo2
Always you should try to add data and DDL for setup correctly the test scenario, here my proposed solution:
DECLARE #SourceA AS TABLE
(
ID INT,
Value INT,
Condition VARCHAR(100)
);
INSERT INTO #SourceA ( ID ,
Value ,
Condition
)
VALUES ( 1 , -- ID - int
110 , -- Value - int
'A-M' -- Condition - varchar(100)
),(2,250,'N-Z')
DECLARE #Alphabet VARCHAR(200)='A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z';
; WITH MyCTE AS
(
SELECT ID,Value,Condition, SUBSTRING(#Alphabet, PATINDEX('%'+ LEFT(Condition,1) + '%' ,#Alphabet),(LEN(#Alphabet)-PATINDEX('%'+ RIGHT(Condition,1) + '%' ,#Alphabet))+1) AS FormattedCondition
FROM #SourceA
)
SELECT * FROM MyCTE
WHERE MyCTE.FormattedCondition LIKE '%C%'
CREATE PROCEDURE [dbo].[uspGetLogs]
(
#StartDate DATETIME,
#EndDate DATETIME
)
AS
SELECT
sl.ID,
LOG10(sl.Value)
FROM
dbo.SampleList sl
INNER JOIN
(
SELECT
ID,
RANK() OVER(PARTITION BY Codec ORDER BY TimeStampUTC DESC, d.ID DESC) ranked
FROM
dbo.SampleList
WHERE
ListDate BETWEEN #StartDate AND #EndDate
) r
ON
r.ID = sl.ID AND
r.ranked = 1
I tried this stored procedure with this #StartDate = 2014-01-29 #EndDate = 2015-03-14.
And gets this error
An invalid floating point operation occurred
The reason of the error "An Invalid floating point operation occured" is the invalid usage of mathematical function.
SELECT LOG10(-3);
SELECT LOG10(0);
If the above functions are run it will return the error.
I able to get a single value from the whole table set where value is less than one. But the ListDate for that value is 2015-03-14 so it should not be included because it is not coverted by the date range passed in the stored procedure.
So it seems that the stored procedure executes the function in the whole set first before joining and filtering the dataset with date range.
Is this expected?
I think there could be a data issue here as the basic logic of your code doesn't cause an issue, see the below sample:
CREATE TABLE #temp1 ( id INT, val INT )
CREATE TABLE #temp2 ( id INT, val INT )
INSERT INTO #temp1 ( id, val )
VALUES ( 1, 1 ), ( 2, 10 ), ( 3, -1 ) -- Negative value for id=3 exculded in subquery
INSERT INTO #temp2 ( id, val )
VALUES ( 1, 1 ), ( 2, 10 ), ( 3, 20 )
SELECT t1.id ,
LOG10(t1.val) AS Val
FROM #temp1 t1
INNER JOIN ( SELECT * ,
RANK() OVER ( PARTITION BY id ORDER BY val ) ranked
FROM #temp2
WHERE id BETWEEN 1 AND 2 -- excludes id 3
) t2 ON t2.id = t1.id
AND t2.ranked = 1
DROP TABLE #temp1
DROP TABLE #temp2
Produces:
id val
1 0
2 1
If you modify the BETWEEN clause to WHERE id BETWEEN 1 AND 3, you do see the error as the negative value is included.
So I'd triple check the data and if there's still an issue, try to post a small sample that recreates the issue.
I dont think there's a guaranteed point where function gets executed, so my answer is it depends, it depends on query plan, on how "early" the optimizer decides to execute the function - before or after the join. To make sure the function is only executed for valid values, you can change to:
CASE WHEN sl.Value < 1 THEN 0 ELSE LOG10(sl.Value) END
Suppose that I have a relation with only 1 column "Value (INT)" and its values are in descending order.
+----------+
+ VALUE +
+----------+
+ 10 +
+ 9 +
+ 8 +
+ 7 +
....
How can list all the combinations which contains two tuples such that the first tuple is greater than the second tuple
Note: It may exist two tuples with same value
The desired outputs should be like: (10,9) (10, 8) (9,8), (9,7) (8,7)
You can do a cross join on the same table.
SELECT t1.VALUE AS VALUE1, t2.VALUE AS VALUE2
FROM thing t1 JOIN thing t2 ON (t1.VALUE != t2.VALUE AND t1.VALUE > t2.VALUE)
I understand that a single tuple may apear only twice on the left side of the resultset, am I right? That's why there is no (10,7)?
Then you need to compute row number.
select t1.value, t2.value
from
(
select t.value, row_number(order by t.value) as rnum
from table t
) t1 inner join
(
select t.value, row_number(order by t.value) as rnum
from table t
) t2 on t1.value > t2.value and t1.rnum < t2.rnum + 2
Performance of this query will be pretty bad, but I don't know what database are you using - I've used MS SQL row_number function.
Another idea:
If you are using SQL Server 2012+ and your answer to the question posed at the begining of this post is positive, you can use:
select t.value, lead(t.value,1,0) over(order by t.value desc) as lead1
lead(t.value,2,0) over(order by t.value desc) as lead2
from table t
You may need to handle 0 (defulat value if there is no "lead" tuple). I'm not sure if output in this form is acceptable.
And here you go with cursor solution:
DECLARE #result TABLE
(
value1 int,
value2 int
);
DECLARE
#value int,
#lag1 int,
#lag2 int
DECLARE c CURSOR LOCAL STATIC FORWARD_ONLY READ_ONLY
FOR
SELECT value
FROM table
ORDER BY value desc
OPEN c;
FETCH NEXT FROM c INTO #lag2;
FETCH NEXT FROM c INTO #lag1;
FETCH NEXT FROM c INTO #value;
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT #result(value1, value2) SELECT #lag2, #lag1
INSERT #result(value1, value2) SELECT #lag2, #value
SET #lag2 = #lag1
SET #lag1 = #value
FETCH NEXT FROM c INTO #value
END
CLOSE c;
Again, I used MS SQL syntax. If you write how you want duplicates handled, I can update the solution.
I have three address line columns, aline1, aline2, aline3 for a street
address. As staged from inconsistent data, any or all of them can be
blank. I want to move the first non-blank to addrline1, 2nd non-blank
to addrline2, and clear line 3 if there aren't three non blank lines,
else leave it. ("First" means aline1 is first unless it's blank,
aline2 is first if aline1 is blank, aline3 is first if aline1 and 2
are both blank)
The rows in this staging table do not have a key and there could be
duplicate rows. I could add a key.
Not counting a big case statement that enumerates the possible
combination of blank and non blank and moves the fields around, how
can I update the table? (This same problem comes up with a lot more
than 3 lines, so that's why I don't want to use a case statement)
I'm using Microsoft SQL Server 2008
Another alternative. It uses the undocumented %%physloc%% function to work without a key. You would be much better off adding a key to the table.
CREATE TABLE #t
(
aline1 VARCHAR(100),
aline2 VARCHAR(100),
aline3 VARCHAR(100)
)
INSERT INTO #t VALUES(NULL, NULL, 'a1')
INSERT INTO #t VALUES('a2', NULL, 'b2')
;WITH cte
AS (SELECT *,
MAX(CASE WHEN RN=1 THEN value END) OVER (PARTITION BY %%physloc%%) AS new_aline1,
MAX(CASE WHEN RN=2 THEN value END) OVER (PARTITION BY %%physloc%%) AS new_aline2,
MAX(CASE WHEN RN=3 THEN value END) OVER (PARTITION BY %%physloc%%) AS new_aline3
FROM #t
OUTER APPLY (SELECT ROW_NUMBER() OVER (ORDER BY CASE WHEN value IS NULL THEN 1 ELSE 0 END, idx) AS
RN, idx, value
FROM (VALUES(1,aline1),
(2,aline2),
(3,aline3)) t (idx, value)) d)
UPDATE cte
SET aline1 = new_aline1,
aline2 = new_aline2,
aline3 = new_aline3
SELECT *
FROM #t
DROP TABLE #t
Here's an alternative
Sample table for discussion, don't worry about the nonsensical data, they just need to be null or not
create table taddress (id int,a varchar(10),b varchar(10),c varchar(10));
insert taddress
select 1,1,2,3 union all
select 2,1, null, 3 union all
select 3,null, 1, 2 union all
select 4,null,null,2 union all
select 5,1, null, null union all
select 6,null, 4, null
The query, which really just normalizes the data
;with tmp as (
select *, rn=ROW_NUMBER() over (partition by t.id order by sort)
from taddress t
outer apply
(
select 1, t.a where t.a is not null union all
select 2, t.b where t.b is not null union all
select 3, t.c where t.c is not null
--- EXPAND HERE
) u(sort, line)
)
select t0.id, t1.line, t2.line, t3.line
from taddress t0
left join tmp t1 on t1.id = t0.id and t1.rn=1
left join tmp t2 on t2.id = t0.id and t2.rn=2
left join tmp t3 on t3.id = t0.id and t3.rn=3
--- AND HERE
order by t0.id
EDIT - for the update back into table
;with tmp as (
select *, rn=ROW_NUMBER() over (partition by t.id order by sort)
from taddress t
outer apply
(
select 1, t.a where t.a is not null union all
select 2, t.b where t.b is not null union all
select 3, t.c where t.c is not null
--- EXPAND HERE
) u(sort, line)
)
UPDATE taddress
set a = t1.line,
b = t2.line,
c = t3.line
from taddress t0
left join tmp t1 on t1.id = t0.id and t1.rn=1
left join tmp t2 on t2.id = t0.id and t2.rn=2
left join tmp t3 on t3.id = t0.id and t3.rn=3
Update - Changed statement to an Update statement. Removed Case statement solution
With this solution, you will need a unique key in the staging table.
With Inputs As
(
Select PK, 1 As LineNum, aline1 As Value
From StagingTable
Where aline1 Is Not Null
Union All
Select PK, 2, aline2
From StagingTable
Where aline2 Is Not Null
Union All
Select PK, 3, aline3
From StagingTable
Where aline3 Is Not Null
)
, ResequencedInputs As
(
Select PK, Value
, Row_Number() Over( Order By LineNum ) As LineNum
From Inputs
)
, NewValues As
(
Select S.PK
, Min( Case When R.LineNum = 1 Then R.addrline1 End ) As addrline1
, Min( Case When R.LineNum = 2 Then R.addrline1 End ) As addrline2
, Min( Case When R.LineNum = 3 Then R.addrline1 End ) As addrline3
From StagingTable As S
Left Join ResequencedInputs As R
On R.PK = S.PK
Group By S.PK
)
Update OtherTable
Set addrline1 = T2.addrline1
, addrline2 = T2.addrline2
, addrline3 = T2.addrline3
From OtherTable As T
Left Join NewValues As T2
On T2.PK = T.PK
R. A. Cyberkiwi, Thomas, and Martin, thanks very much - these were very generous responses by each of you. All of these answers were the type of spoonfeeding I was looking for. I'd say they all rely on a key-like device and work by dividing addresses into lines, some of which are empty and some of which aren't, excluding the empties. In the case of lines of addresses, in my opinion this is semantically a gimmick to make the problem fit what SQL does well, and it's not a natural way to conceptualize the problem. Address lines are not "really" separate rows in a table that just got denormalized for a report. But that's debatable and whether you agree or not, I (a rank beginner) think each of your alternatives are idiomatic solutions worth elaborating on and studying.
I also get lots of similar cases where there really is normalization to be done - e.g., collatDesc1, collatCode1, collatLastAppraisal1, ... collatLastAppraisal5, with more complex criteria about what in excludeand how to order than with addresses, and I think techniques from your answers will be helpful.
%%phsloc%% is fun - since I'm able to create a key in this case I won't use it (as Martin advises). There was other stuff in Martin's stuff I wasn't familiar with too, and I'm still tossing them all around.
FWIW, here's the trigger I tried out, I don't know that I'll actually use it for the problem at hand. I think this qualifies a "bubble sort", with the swapping expressed in a peculiar way.
create trigger fixit on lines
instead of insert as
declare #maybeblank1 as varchar(max)
declare #maybeblank2 as varchar(max)
declare #maybeblank3 as varchar(max)
set #maybeBlank1 = (select line1 from inserted)
set #maybeBlank2 = (select line2 from inserted)
set #maybeBlank3 = (select line3 from inserted)
declare #counter int
set #counter = 0
while #counter < 3
begin
set #counter = #counter + 1
if #maybeBlank2 = ''
begin
set #maybeBlank2 =#maybeblank3
set #maybeBlank3 = ''
end
if #maybeBlank1 = ''
begin
set #maybeBlank1 = #maybeBlank2
set #maybeBlank2 = ''
end
end
select * into #kludge from inserted
update #kludge
set line1 = #maybeBlank1,
line2 = #maybeBlank2,
line3 = #maybeBlank3
insert into lines
select * from #kludge
You could make an insert and update trigger that check if the fields are empty and then move them.
I'd like to find the first "gap" in a counter column in an SQL table. For example, if there are values 1,2,4 and 5 I'd like to find out 3.
I can of course get the values in order and go through it manually, but I'd like to know if there would be a way to do it in SQL.
In addition, it should be quite standard SQL, working with different DBMSes.
In MySQL and PostgreSQL:
SELECT id + 1
FROM mytable mo
WHERE NOT EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = mo.id + 1
)
ORDER BY
id
LIMIT 1
In SQL Server:
SELECT TOP 1
id + 1
FROM mytable mo
WHERE NOT EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = mo.id + 1
)
ORDER BY
id
In Oracle:
SELECT *
FROM (
SELECT id + 1 AS gap
FROM mytable mo
WHERE NOT EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = mo.id + 1
)
ORDER BY
id
)
WHERE rownum = 1
ANSI (works everywhere, least efficient):
SELECT MIN(id) + 1
FROM mytable mo
WHERE NOT EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = mo.id + 1
)
Systems supporting sliding window functions:
SELECT -- TOP 1
-- Uncomment above for SQL Server 2012+
previd
FROM (
SELECT id,
LAG(id) OVER (ORDER BY id) previd
FROM mytable
) q
WHERE previd <> id - 1
ORDER BY
id
-- LIMIT 1
-- Uncomment above for PostgreSQL
Your answers all work fine if you have a first value id = 1, otherwise this gap will not be detected. For instance if your table id values are 3,4,5, your queries will return 6.
I did something like this
SELECT MIN(ID+1) FROM (
SELECT 0 AS ID UNION ALL
SELECT
MIN(ID + 1)
FROM
TableX) AS T1
WHERE
ID+1 NOT IN (SELECT ID FROM TableX)
There isn't really an extremely standard SQL way to do this, but with some form of limiting clause you can do
SELECT `table`.`num` + 1
FROM `table`
LEFT JOIN `table` AS `alt`
ON `alt`.`num` = `table`.`num` + 1
WHERE `alt`.`num` IS NULL
LIMIT 1
(MySQL, PostgreSQL)
or
SELECT TOP 1 `num` + 1
FROM `table`
LEFT JOIN `table` AS `alt`
ON `alt`.`num` = `table`.`num` + 1
WHERE `alt`.`num` IS NULL
(SQL Server)
or
SELECT `num` + 1
FROM `table`
LEFT JOIN `table` AS `alt`
ON `alt`.`num` = `table`.`num` + 1
WHERE `alt`.`num` IS NULL
AND ROWNUM = 1
(Oracle)
The first thing that came into my head. Not sure if it's a good idea to go this way at all, but should work. Suppose the table is t and the column is c:
SELECT
t1.c + 1 AS gap
FROM t as t1
LEFT OUTER JOIN t as t2 ON (t1.c + 1 = t2.c)
WHERE t2.c IS NULL
ORDER BY gap ASC
LIMIT 1
Edit: This one may be a tick faster (and shorter!):
SELECT
min(t1.c) + 1 AS gap
FROM t as t1
LEFT OUTER JOIN t as t2 ON (t1.c + 1 = t2.c)
WHERE t2.c IS NULL
This works in SQL Server - can't test it in other systems but it seems standard...
SELECT MIN(t1.ID)+1 FROM mytable t1 WHERE NOT EXISTS (SELECT ID FROM mytable WHERE ID = (t1.ID + 1))
You could also add a starting point to the where clause...
SELECT MIN(t1.ID)+1 FROM mytable t1 WHERE NOT EXISTS (SELECT ID FROM mytable WHERE ID = (t1.ID + 1)) AND ID > 2000
So if you had 2000, 2001, 2002, and 2005 where 2003 and 2004 didn't exist, it would return 2003.
The following solution:
provides test data;
an inner query that produces other gaps; and
it works in SQL Server 2012.
Numbers the ordered rows sequentially in the "with" clause and then reuses the result twice with an inner join on the row number, but offset by 1 so as to compare the row before with the row after, looking for IDs with a gap greater than 1. More than asked for but more widely applicable.
create table #ID ( id integer );
insert into #ID values (1),(2), (4),(5),(6),(7),(8), (12),(13),(14),(15);
with Source as (
select
row_number()over ( order by A.id ) as seq
,A.id as id
from #ID as A WITH(NOLOCK)
)
Select top 1 gap_start from (
Select
(J.id+1) as gap_start
,(K.id-1) as gap_end
from Source as J
inner join Source as K
on (J.seq+1) = K.seq
where (J.id - (K.id-1)) <> 0
) as G
The inner query produces:
gap_start gap_end
3 3
9 11
The outer query produces:
gap_start
3
Inner join to a view or sequence that has a all possible values.
No table? Make a table. I always keep a dummy table around just for this.
create table artificial_range(
id int not null primary key auto_increment,
name varchar( 20 ) null ) ;
-- or whatever your database requires for an auto increment column
insert into artificial_range( name ) values ( null )
-- create one row.
insert into artificial_range( name ) select name from artificial_range;
-- you now have two rows
insert into artificial_range( name ) select name from artificial_range;
-- you now have four rows
insert into artificial_range( name ) select name from artificial_range;
-- you now have eight rows
--etc.
insert into artificial_range( name ) select name from artificial_range;
-- you now have 1024 rows, with ids 1-1024
Then,
select a.id from artificial_range a
where not exists ( select * from your_table b
where b.counter = a.id) ;
This one accounts for everything mentioned so far. It includes 0 as a starting point, which it will default to if no values exist as well. I also added the appropriate locations for the other parts of a multi-value key. This has only been tested on SQL Server.
select
MIN(ID)
from (
select
0 ID
union all
select
[YourIdColumn]+1
from
[YourTable]
where
--Filter the rest of your key--
) foo
left join
[YourTable]
on [YourIdColumn]=ID
and --Filter the rest of your key--
where
[YourIdColumn] is null
For PostgreSQL
An example that makes use of recursive query.
This might be useful if you want to find a gap in a specific range
(it will work even if the table is empty, whereas the other examples will not)
WITH
RECURSIVE a(id) AS (VALUES (1) UNION ALL SELECT id + 1 FROM a WHERE id < 100), -- range 1..100
b AS (SELECT id FROM my_table) -- your table ID list
SELECT a.id -- find numbers from the range that do not exist in main table
FROM a
LEFT JOIN b ON b.id = a.id
WHERE b.id IS NULL
-- LIMIT 1 -- uncomment if only the first value is needed
My guess:
SELECT MIN(p1.field) + 1 as gap
FROM table1 AS p1
INNER JOIN table1 as p3 ON (p1.field = p3.field + 2)
LEFT OUTER JOIN table1 AS p2 ON (p1.field = p2.field + 1)
WHERE p2.field is null;
I wrote up a quick way of doing it. Not sure this is the most efficient, but gets the job done. Note that it does not tell you the gap, but tells you the id before and after the gap (keep in mind the gap could be multiple values, so for example 1,2,4,7,11 etc)
I'm using sqlite as an example
If this is your table structure
create table sequential(id int not null, name varchar(10) null);
and these are your rows
id|name
1|one
2|two
4|four
5|five
9|nine
The query is
select a.* from sequential a left join sequential b on a.id = b.id + 1 where b.id is null and a.id <> (select min(id) from sequential)
union
select a.* from sequential a left join sequential b on a.id = b.id - 1 where b.id is null and a.id <> (select max(id) from sequential);
https://gist.github.com/wkimeria/7787ffe84d1c54216f1b320996b17b7e
Here is an alternative to show the range of all possible gap values in portable and more compact way :
Assume your table schema looks like this :
> SELECT id FROM your_table;
+-----+
| id |
+-----+
| 90 |
| 103 |
| 104 |
| 118 |
| 119 |
| 120 |
| 121 |
| 161 |
| 162 |
| 163 |
| 185 |
+-----+
To fetch the ranges of all possible gap values, you have the following query :
The subquery lists pairs of ids, each of which has the lowerbound column being smaller than upperbound column, then use GROUP BY and MIN(m2.id) to reduce number of useless records.
The outer query further removes the records where lowerbound is exactly upperbound - 1
My query doesn't (explicitly) output the 2 records (YOUR_MIN_ID_VALUE, 89) and (186, YOUR_MAX_ID_VALUE) at both ends, that implicitly means any number in both of the ranges hasn't been used in your_table so far.
> SELECT m3.lowerbound + 1, m3.upperbound - 1 FROM
(
SELECT m1.id as lowerbound, MIN(m2.id) as upperbound FROM
your_table m1 INNER JOIN your_table
AS m2 ON m1.id < m2.id GROUP BY m1.id
)
m3 WHERE m3.lowerbound < m3.upperbound - 1;
+-------------------+-------------------+
| m3.lowerbound + 1 | m3.upperbound - 1 |
+-------------------+-------------------+
| 91 | 102 |
| 105 | 117 |
| 122 | 160 |
| 164 | 184 |
+-------------------+-------------------+
select min([ColumnName]) from [TableName]
where [ColumnName]-1 not in (select [ColumnName] from [TableName])
and [ColumnName] <> (select min([ColumnName]) from [TableName])
Here is standard a SQL solution that runs on all database servers with no change:
select min(counter + 1) FIRST_GAP
from my_table a
where not exists (select 'x' from my_table b where b.counter = a.counter + 1)
and a.counter <> (select max(c.counter) from my_table c);
See in action for;
PL/SQL via Oracle's livesql,
MySQL via sqlfiddle,
PostgreSQL via sqlfiddle
MS Sql via sqlfiddle
It works for empty tables or with negatives values as well. Just tested in SQL Server 2012
select min(n) from (
select case when lead(i,1,0) over(order by i)>i+1 then i+1 else null end n from MyTable) w
If You use Firebird 3 this is most elegant and simple:
select RowID
from (
select `ID_Column`, Row_Number() over(order by `ID_Column`) as RowID
from `Your_Table`
order by `ID_Column`)
where `ID_Column` <> RowID
rows 1
-- PUT THE TABLE NAME AND COLUMN NAME BELOW
-- IN MY EXAMPLE, THE TABLE NAME IS = SHOW_GAPS AND COLUMN NAME IS = ID
-- PUT THESE TWO VALUES AND EXECUTE THE QUERY
DECLARE #TABLE_NAME VARCHAR(100) = 'SHOW_GAPS'
DECLARE #COLUMN_NAME VARCHAR(100) = 'ID'
DECLARE #SQL VARCHAR(MAX)
SET #SQL =
'SELECT TOP 1
'+#COLUMN_NAME+' + 1
FROM '+#TABLE_NAME+' mo
WHERE NOT EXISTS
(
SELECT NULL
FROM '+#TABLE_NAME+' mi
WHERE mi.'+#COLUMN_NAME+' = mo.'+#COLUMN_NAME+' + 1
)
ORDER BY
'+#COLUMN_NAME
-- SELECT #SQL
DECLARE #MISSING_ID TABLE (ID INT)
INSERT INTO #MISSING_ID
EXEC (#SQL)
--select * from #MISSING_ID
declare #var_for_cursor int
DECLARE #LOW INT
DECLARE #HIGH INT
DECLARE #FINAL_RANGE TABLE (LOWER_MISSING_RANGE INT, HIGHER_MISSING_RANGE INT)
DECLARE IdentityGapCursor CURSOR FOR
select * from #MISSING_ID
ORDER BY 1;
open IdentityGapCursor
fetch next from IdentityGapCursor
into #var_for_cursor
WHILE ##FETCH_STATUS = 0
BEGIN
SET #SQL = '
DECLARE #LOW INT
SELECT #LOW = MAX('+#COLUMN_NAME+') + 1 FROM '+#TABLE_NAME
+' WHERE '+#COLUMN_NAME+' < ' + cast( #var_for_cursor as VARCHAR(MAX))
SET #SQL = #sql + '
DECLARE #HIGH INT
SELECT #HIGH = MIN('+#COLUMN_NAME+') - 1 FROM '+#TABLE_NAME
+' WHERE '+#COLUMN_NAME+' > ' + cast( #var_for_cursor as VARCHAR(MAX))
SET #SQL = #sql + 'SELECT #LOW,#HIGH'
INSERT INTO #FINAL_RANGE
EXEC( #SQL)
fetch next from IdentityGapCursor
into #var_for_cursor
END
CLOSE IdentityGapCursor;
DEALLOCATE IdentityGapCursor;
SELECT ROW_NUMBER() OVER(ORDER BY LOWER_MISSING_RANGE) AS 'Gap Number',* FROM #FINAL_RANGE
Found most of approaches run very, very slow in mysql. Here is my solution for mysql < 8.0. Tested on 1M records with a gap near the end ~ 1sec to finish. Not sure if it fits other SQL flavours.
SELECT cardNumber - 1
FROM
(SELECT #row_number := 0) as t,
(
SELECT (#row_number:=#row_number+1), cardNumber, cardNumber-#row_number AS diff
FROM cards
ORDER BY cardNumber
) as x
WHERE diff >= 1
LIMIT 0,1
I assume that sequence starts from `1`.
If your counter is starting from 1 and you want to generate first number of sequence (1) when empty, here is the corrected piece of code from first answer valid for Oracle:
SELECT
NVL(MIN(id + 1),1) AS gap
FROM
mytable mo
WHERE 1=1
AND NOT EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = mo.id + 1
)
AND EXISTS
(
SELECT NULL
FROM mytable mi
WHERE mi.id = 1
)
DECLARE #Table AS TABLE(
[Value] int
)
INSERT INTO #Table ([Value])
VALUES
(1),(2),(4),(5),(6),(10),(20),(21),(22),(50),(51),(52),(53),(54),(55)
--Gaps
--Start End Size
--3 3 1
--7 9 3
--11 19 9
--23 49 27
SELECT [startTable].[Value]+1 [Start]
,[EndTable].[Value]-1 [End]
,([EndTable].[Value]-1) - ([startTable].[Value]) Size
FROM
(
SELECT [Value]
,ROW_NUMBER() OVER(PARTITION BY 1 ORDER BY [Value]) Record
FROM #Table
)AS startTable
JOIN
(
SELECT [Value]
,ROW_NUMBER() OVER(PARTITION BY 1 ORDER BY [Value]) Record
FROM #Table
)AS EndTable
ON [EndTable].Record = [startTable].Record+1
WHERE [startTable].[Value]+1 <>[EndTable].[Value]
If the numbers in the column are positive integers (starting from 1) then here is how to solve it easily. (assuming ID is your column name)
SELECT TEMP.ID
FROM (SELECT ROW_NUMBER() OVER () AS NUM FROM 'TABLE-NAME') AS TEMP
WHERE ID NOT IN (SELECT ID FROM 'TABLE-NAME')
ORDER BY 1 ASC LIMIT 1
SELECT ID+1 FROM table WHERE ID+1 NOT IN (SELECT ID FROM table) ORDER BY 1;