I want a sql query:
I have list of number and want to find out the FIRST missing number if there is no missing number in the list then give me the next available number
for example I have a column data 1,2,4, that means I need three which is a missing number and If i have 1,2,3,4 then i need number 5. Please help thanks
You could use this query:
SELECT MIN(t1.Number) + 1 AS MissingNumber
FROM dbo.TableName t1
LEFT OUTER JOIN dbo.TableName t2
ON (t1.Number + 1 = t2.Number)
WHERE t2.Number IS NULL
However, this is a race condition, the first wins. Normally you should not fill gaps. If it's a key column you could use an IDENTITY column with auto increment.
-- Note the +1, so to include the next number if the sequence is "complete",
-- And the isnull(,0) to handle the "empty table" case
declare #m as int = (select isnull(max(id), 0) + 1 from yourtable)
-- Sequence 1...#m of numbers
;with t as (
select 1 x
union all
select x + 1
from t
where x <= #m)
-- Find the minimum missing numebr
select min(x) from t where not exists (select 1 from yourtable where id = x)
Where yourtable is the table you want to find the missing numbers from and id is the column of which you want to find the missing numbers.
Related
Given this query, if I want to pull the rank of a specific individual where I know there $name and $score and return the rows above/below that rank (say +/- 4), how would I go about doing that?
$query = "SELECT #curRank := #curRank + 1 AS Rank,
uniqueID,
name,
score
FROM scores, (SELECT #curRank := 0) r
ORDER by score DESC";
I'm coding in php, using MySQL and C# in Unity. My game is making a call to the server and running the php code. Goal is to echo the information and parse the information back in the game.
Any help would be much appreciated :)
Based off of your :=, I'm assuming you are using PostgreSQL, correct? I'm more familiar with the T-SQL syntax; but regardless, both PostgreSQL and T-SQL have windowing functions. You could implement something similar to the following (I left out variables for you to fill-in):
$query = "WITH scoreOrder
AS
(
SELECT uniqueID,
name,
score,
ROW_NUMBER() OVER (ORDER BY score DESC, uniqueID DESC) AS RowNum
FROM scores
ORDER BY uniqueID DESC
)
SELECT ns.*
FROM scoreOrder ms --Your matching score
INNER JOIN scoreOrder ns --Your nearby scores
ON ms.name = /* your name variable */
AND ms.score = /* your score variable */
AND ns.RowNum BETWEEN ms.RowNum - /* your offset */ and ms.RowNum + /* your offset */";
Explanation: First, we're creating a common table expression called scoreOrder, and projecting a RowNum column for your scores. In short, ROW_NUMBER() OVER (ORDER BY score DESC, uniqueID DESC) is just saying, "I am returning the row number of this record ordered by score and uniqueID, both descending and in that order." Then, you join that CTE with itself... ms will be your score that you match with, and you join that with ns where the ns.RowNum will be between your ms.RowNum, plus or minus your offset.
There are a ton of other windowing functions. Here are some others that could be more or less appropriate for your scenario:
ROW_NUMBER() - the rownumber of the record
RANK() - the rank of the record, duplicating in ties and includes
gaps (i.e., if 2nd place ties, you would have 1st, 2nd, 2nd,
4th)
DENSE_RANK() - same as rank, except that it fills in the gaps
(i.e., if 2nd place ties, you would have 1st, 2nd, 2nd, 3rd)
For more info, check the PostgreSQL documentation on windowing functions and their tutorial
Update:
Unfornately, MySQL does not support windowing functions or common table expressions. In your scenario, you will have to put the results of your previous query into a temp table, then doing a similar join as demonstrated above. So for example...
CREATE TEMPORARY TABLE IF NOT EXISTS allRankings AS
(
SELECT #curRank := #curRank + 1 AS Rank,
uniqueID,
name,
score
FROM scores, (SELECT #curRank := 0) r
ORDER by score DESC, uniqueID
);
SELECT r.*
FROM allRankings r
INNER JOIN allRankings myRank
ON r.Rank BETWEEN myRank.Rank - <your offset> AND myRank.Rank + <your offset>
AND myRank.name = <your name>
AND myRank.score = <your score>
ORDER by r.Rank;
Here is a SQLFiddle link for an example. (I'm not using a temp table on SQLFiddle because you have to build tables in the Build Schema window).
I have a stored procedure that inserts a line in a table. This table has an auto incremented int primary key and a datetime2 column named CreationDate. I am calling it in a for loop via my C# code, and the loop is inside a transaction scope.
I run the program twice, first time with a for loop that turned 6 times and second time with a for loop that turned 2 times. When I executed this select on sql server I got a strange result
SELECT TOP 8
RequestId, CreationDate
FROM
PickupRequest
ORDER BY
CreationDate DESC
What I didn't get is the order of insertion: for example the line with Id=58001 has to be inserted after that with Id=58002 but this is not the case. Is that because I put my loop in a transaction scoope? or the precision in the datetime2 is not enough?
It is a question of speed and statement scope as well...
Try this:
--This will create a #numbers table with 1 mio numbers:
DECLARE #numbers TABLE(Nbr BIGINT);
WITH N(N) AS
(SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1)
,MoreN(N) AS
(SELECT 1 FROM N AS N1 CROSS JOIN N AS N2 CROSS JOIN N AS N3 CROSS JOIN N AS N4 CROSS JOIN N AS N5 CROSS JOIN N AS N6)
INSERT INTO #numbers(Nbr)
SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL))
FROM MoreN;
--This is a dummy table for inserts:
CREATE TABLE Dummy(ID INT IDENTITY,CreationDate DATETIME);
--Play around with the value for #Count. You can insert 1 mio rows in one go. Although this runs a while, all will have the same datetime value:
--Use a small number here and below, still the same time value
--Use a big count here and a small below will show a slightly later value for the second insert
DECLARE #Count INT = 1000;
INSERT INTO Dummy (CreationDate)
SELECT GETDATE()
FROM (SELECT TOP(#Count) 1 FROM #numbers) AS X(Y);
--A second insert
SET #Count = 10;
INSERT INTO Dummy (CreationDate)
SELECT GETDATE()
FROM (SELECT TOP(#Count) 1 FROM #numbers) AS X(Y);
SELECT * FROM Dummy;
--Clean up
GO
DROP TABLE Dummy;
You did your insertions pretty fast so the actual CreationDate values inserted in one program run had the same values. In case you're using datetime type, all the insertions may well occur in one millisecond. So ORDER BY CreationDate DESC by itself does not guarantee the select order to be that of insertion.
To get the desired order you need to sort by the RequestId as well:
SELECT TOP 8 RequestId, CreationDate
FROM PickupRequest
ORDER BY CreationDate DESC, RequestId DESC
Given data
I need to come up to this by including SalesNew column:
SalesNew column will compute for the sum of each items sales based on their group number conditionally.
Example based on the table above. when the group number of item is 1, IT WILL JUST COPY OR RETAIN ITS SALES. When it is not 1, SalesNew column should get the sum of all items per group, like in the given example, salesNew displays 20 for item 3 and item 4 because it adds their sales that both having 10. So item 3 and 4 salesNew value is 20.
I know the sum function but this doesn't display the desired output. I hope anyone could help me out on this.
Thanks in advance
You could use SUM(Sales) OVER(PARTITION BY [Group]), with a combination of CASE:
SELECT *,
salesNew =
CASE
WHEN [Group] = 1 THEN Sales
ELSE SUM(Sales) OVER(PARTITION BY [Group])
END
FROM Data
SQL Fiddle
You could also use CROSS APPLY:
SELECT
d.*,
salesNew =
CASE
WHEN [Group] = 1 THEN Sales
ELSE x.salesNew
END
FROM Data d
CROSS APPLY(
SELECT salesNew = SUM(Sales)
FROM Data
WHERE [Group] = d.[Group]
)x
SQL Fiddle
getName_as_Rows is an array which contains some names.
I want to set an int value to 1 if record found in data base.
for(int i = 0; i<100; i++)
{
using (var command = new SqlCommand("select some column from some table where column = #Value", con1))
{
command.Parameters.AddWithValue("#Value", getName_as_Rows[i]);
con1.Open();
command.ExecuteNonQuery();
}
}
I am looking for:
bool recordexist;
if the above record exist then bool = 1 else 0 with in the loop.
If have to do some other stuff if the record exist.
To avoid making N queries to the database, something that could be very expensive in terms of processing, network and so worth, I suggest you to Join only once using a trick I learned. First you need a function in your database that splits a string into a table.
CREATE FUNCTION [DelimitedSplit8K]
--===== Define I/O parameters
(#pString VARCHAR(8000), #pDelimiter CHAR(1))
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
--===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
-- enough to cover VARCHAR(8000)
WITH E1(N) AS (
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
), --10E+1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS (--==== This provides the "zero base" and limits the number of rows right up front
-- for both a performance gain and prevention of accidental "overruns"
SELECT 0 UNION ALL
SELECT TOP (DATALENGTH(ISNULL(#pString,1))) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
SELECT t.N+1
FROM cteTally t
WHERE (SUBSTRING(#pString,t.N,1) = #pDelimiter OR t.N = 0)
)
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY s.N1),
Item = SUBSTRING(#pString,s.N1,ISNULL(NULLIF(CHARINDEX(#pDelimiter,#pString,s.N1),0)-s.N1,8000))
FROM cteStart s
GO
Second, concatenate your 100 variables into 1 string:
"Value1", "Value 2", "Value 3"....
In Sql Server you can just join the values with your table
SELECT somecolumn FROM sometable t
INNER JOIN [DelimitedSplit8K](#DelimitedString, ',') v ON v.Item = t.somecolumn
So you find 100 strings at a time with only 1 query.
Use var result = command.ExecuteScalar() and check if result != null
But a better option than to loop would be to say use a select statement like
SELECT COUNT(*) FROM TABLE WHERE COLUMNVAL >= 0 AND COLUMNVAL < 100,
and run ExecuteScalar on that, and if the value is > 0, then set your variable to 1.
This may be a very silly mistake but I just can't fix it. I have 2 tables, Questions and Questions_Rating.
Questions:
question_id question user_id
------------------------------------------
1 'How to blablabla' 1
2 'bla bla bla' 1
Questions_Rating
In this table, users will rate questions either by +1 or -1
question_rating_id question_id user_id rate
------------------------------------------------------
1 1 2 (+1)
2 1 3 (+1)
3 1 4 ( 1)
Now I would simply like to fetch the question from the questions table, and the SUM of the rate in the questions_rating table for this question, which has an ID = 1.
String QUERY = "SELECT q.question, SUM(r.rate) FROM questions q, questions_rating r WHERE r.question_id = q.question_id AND q.question_id = 1";
And this is what I'm getting.
Column 'questions.question' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
I know that the SUM of the rate will return 1 row, and the question is supposedly 1 row, I can't figure out what's wrong with this query.
I am using SQL Server 2008.
You will have to Group the values as per the question so you need a
GROUP BY q.question
at the end of your query
Good Explanation here
You need the group by q.question in your SQL statement.
Your Sum is suppose to return only a single row against the table, since you are selecting a column along with the Sum you need to specify a group on the selected column. In your case it should be q.question, and sum will be applied to each group of questions.
SELECT q.question,SUM(r.rate) AS RateSum
FROM questions q,questions_rating r
WHERE r.question_id = q.question_id AND q.question_id=1
GROUP BY q.question
or (using ANSI 92 style joins)
SELECT q.question,SUM(r.rate) AS RateSum
FROM questions q INNER JOIN questions_rating r ON r.question_id = q.question_id
WHERE q.question_id=1
GROUP BY q.question
or (using subqueries)
SELECT q.question, (SELECT SUM(r.rate) FROM questions_rating r WHERE r.question_id = q.question_id) AS RateSum
FROM questions q
WHERE q.question_id=1
You are missing group by clause in your select statement.
As you have used sum() function which is an aggregate function
So you need to write group by for all the select columns.
String QUERY = "SELECT
q.question,
SUM(r.rate)
FROM
questions q,
questions_rating r
where
r.question_id = q.question_id AND
q.question_id=1
group by
q.question";