I got an error when I tried to solve this problem. First I need to count all values of 2 tables then I need in where condition get all max values.
My code:
Select *
FROM (
select Operator.OperatoriausPavadinimas,
(
select count(*)
from Plan
where Plan.operatoriausID= Operator.operatoriausID
) as NumberOFPlans
from Operator
)a
where a.NumberOFPlans= Max(a.NumberOFPlans)
I get this error
Msg 147, Level 15, State 1, Line 19
An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference.
I don't know how to solve this.
I need get this http://prntscr.com/p700w9
Update 1
Plan table contains of http://prntscr.com/p7055l values and
Operator table contains of http://prntscr.com/p705k0 values.
Are you looking for... an aggregate query that joins both tables and returns the record that has the maximum count?
I suspect that this might phrase as follows:
SELECT TOP(1) o.OperatoriausPavadinimas, COUNT(*)
FROM Operatorius o
INNER JOIN Planas p ON p.operatoriausID = o.operatoriausID
GROUP BY o.OperatoriausPavadinimas
ORDER BY COUNT(*) DESC
If you want to allow ties, you can use TOP(1) WITH TIES.
You can use top with ties. Your query is a bit hard to follow, but I think you want:
select top (1) with ties o.OperatoriausPavadinimas, count(*)
from plan p join
operator o
on p.operatoriausID = o.operatoriausID
group by o.OperatoriausPavadinimas
order by count(*) desc;
Related
I need to calculate the difference of a column between two lines of a table. Is there any way I can do this directly in SQL? I'm using Microsoft SQL Server 2008.
I'm looking for something like this:
SELECT value - (previous.value) FROM table
Imagining that the "previous" variable reference the latest selected row. Of course with a select like that I will end up with n-1 rows selected in a table with n rows, that's not a probably, actually is exactly what I need.
Is that possible in some way?
Use the lag function:
SELECT value - lag(value) OVER (ORDER BY Id) FROM table
Sequences used for Ids can skip values, so Id-1 does not always work.
SQL has no built in notion of order, so you need to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) then I don't know of a way to do that in standard SQL, but most SQL implementations will have extensions to do it.
Here is a way for SQL server that works if you can order rows such that each one is distinct:
select rank() OVER (ORDER BY id) as 'Rank', value into temp1 from t
select t1.value - t2.value from temp1 t1, temp1 t2
where t1.Rank = t2.Rank - 1
drop table temp1
If you need to break ties, you can add as many columns as necessary to the ORDER BY.
WITH CTE AS (
SELECT
rownum = ROW_NUMBER() OVER (ORDER BY columns_to_order_by),
value
FROM table
)
SELECT
curr.value - prev.value
FROM CTE cur
INNER JOIN CTE prev on prev.rownum = cur.rownum - 1
Oracle, PostgreSQL, SQL Server and many more RDBMS engines have analytic functions called LAG and LEAD that do this very thing.
In SQL Server prior to 2012 you'd need to do the following:
SELECT value - (
SELECT TOP 1 value
FROM mytable m2
WHERE m2.col1 < m1.col1 OR (m2.col1 = m1.col1 AND m2.pk < m1.pk)
ORDER BY
col1, pk
)
FROM mytable m1
ORDER BY
col1, pk
, where COL1 is the column you are ordering by.
Having an index on (COL1, PK) will greatly improve this query.
LEFT JOIN the table to itself, with the join condition worked out so the row matched in the joined version of the table is one row previous, for your particular definition of "previous".
Update: At first I was thinking you would want to keep all rows, with NULLs for the condition where there was no previous row. Reading it again you just want that rows culled, so you should an inner join rather than a left join.
Update:
Newer versions of Sql Server also have the LAG and LEAD Windowing functions that can be used for this, too.
select t2.col from (
select col,MAX(ID) id from
(
select ROW_NUMBER() over(PARTITION by col order by col) id ,col from testtab t1) as t1
group by col) as t2
The selected answer will only work if there are no gaps in the sequence. However if you are using an autogenerated id, there are likely to be gaps in the sequence due to inserts that were rolled back.
This method should work if you have gaps
declare #temp (value int, primaryKey int, tempid int identity)
insert value, primarykey from mytable order by primarykey
select t1.value - t2.value from #temp t1
join #temp t2
on t1.tempid = t2.tempid - 1
Another way to refer to the previous row in an SQL query is to use a recursive common table expression (CTE):
CREATE TABLE t (counter INTEGER);
INSERT INTO t VALUES (1),(2),(3),(4),(5);
WITH cte(counter, previous, difference) AS (
-- Anchor query
SELECT MIN(counter), 0, MIN(counter)
FROM t
UNION ALL
-- Recursive query
SELECT t.counter, cte.counter, t.counter - cte.counter
FROM t JOIN cte ON cte.counter = t.counter - 1
)
SELECT counter, previous, difference
FROM cte
ORDER BY counter;
Result:
counter
previous
difference
1
0
1
2
1
1
3
2
1
4
3
1
5
4
1
The anchor query generates the first row of the common table expression cte where it sets cte.counter to column t.counter in the first row of table t, cte.previous to 0, and cte.difference to the first row of t.counter.
The recursive query joins each row of common table expression cte to the previous row of table t. In the recursive query, cte.counter refers to t.counter in each row of table t, cte.previous refers to cte.counter in the previous row of cte, and t.counter - cte.counter refers to the difference between these two columns.
Note that a recursive CTE is more flexible than the LAG and LEAD functions because a row can refer to any arbitrary result of a previous row. (A recursive function or process is one where the input of the process is the output of the previous iteration of that process, except the first input which is a constant.)
I tested this query at SQLite Online.
You can use the following funtion to get current row value and previous row value:
SELECT value,
min(value) over (order by id rows between 1 preceding and 1
preceding) as value_prev
FROM table
Then you can just select value - value_prev from that select and get your answer
I have just started learning MS SQL Server and came across a problem to find median value of LAT_N from a DB on HackerRank.
Here's the problem.
Here's the DB schema if aren't able to view the above link without logging in.
Here's my code.
SELECT
CASE
WHEN COUNT(LAT_N)%2=0 THEN TOP COUNT(LAT_N)/2 LAT_N
ELSE TOP COUNT(LAT_N)/2+1 LAT_N
END as col1
INTO T1
FROM STATION
ORDER BY LAT_N ASC;
SELECT TOP COUNT(LAT_N)/2 LAT_N AS col2
INTO T2
FROM STATION
ORDER BY LAT_N DESC;
SELECT TOP 1 col1
FROM T1
ORDER BY LAT_N DESC;
SELECT TOP 1 col2
FROM T2
ORDER BY LAT_N ASC;
And I got here's the error:
Msg 156, Level 15, State 1, Server dbrank-tsql, Line 4
Incorrect syntax near the keyword 'TOP'.
So I decided to try it on a small database on W3schools.
Here's the editor.
This query works:
SELECT TOP 3 *
FROM Customers;
But this doesn't:
SELECT TOP COUNT(*)/2 *
FROM Customers;
Can someone please explain:
Why it doesn't work and
How to make TOP COUNT(*)/2 work.
Your SQL doesn't make sense. TOP needs a scalar value after it, and if it's an expression, it need to be in parenthesis (()). SELECT TOP COUNT(*)/2 * doesn't make sense, as you want to TOP what? Then you have COUNT(*)/2 * What are you then multiplying that value by? You're missing part of the expression.
The same is true for SELECT TOP COUNT(LAT_N)/2 LAT_N AS col2. The TOP what? You're missing a value for your TOP and then go straight to asking for a COUNT of the non-NULL values of LAT_N divided by 2. It then appears your missing a comma, but considering you are returning a COUNT of LAT_N it would need to be in your GROUP BY so it is unclear what your goal is there.
If you after the top "half" of the table, (from your comment "How to make TOP COUNT()/2 work."*) use TOP(50 PERCENT):
SELECT TOP (50 PERCENT)
*
FROM dbo.CUSTOMERS
ORDER BY ???;
SELECT TOP ((SELECT COUNT(*) FROM CUSTOMERS) / 2) *
FROM CUSTOMERS
Like Larnu he said I think the best option is to select the TOP X PERCENT and if you've got a column, like created date for eg you can get the most recent 50% rows created:
SELECT TOP 50 PERCENT
*
FROM
CUSTOMERS
ORDER BY
CreatedDate DESC
The TOP requires two parameters:
PARAMETER 1. how many records,
PARAMETER 2. which columns you want to get.
Here is an example usage of the TOP (adapted to your question)
SELECT TOP
/* PARAMETER 1. how many records, in this case half: */
((SELECT COUNT(LAT_N) FROM [STATION]) / 2)
/* PARAMETER 2. which columns you want to get, use star for ALL: */
*
FROM [STATION];
You can also use calculations for choosing the desired number of records.
Here is an example with CASE
SELECT TOP (
/* PARAMETER 1. how many records, in this case
if total number of records in a table is even, then get top half of the rows,
otherwise, make it even, then get the top half: */
CASE
WHEN (SELECT COUNT(LAT_N) FROM [STATION]) % 2 = 0
THEN ((SELECT COUNT(LAT_N) FROM [STATION]) )
ELSE
((SELECT COUNT(LAT_N) + 1 FROM [STATION]) / 2)
END
)
/* PARAMETER 2. which columns you want to get, use star for ALL: */
*
FROM [STATION];
I have a simple select statement. It's basically 2 CTE's, one includes a ROW_NUMBER() OVER (PARTITION BY, then a join from these into 4 other tables. No functions or anything unusual.
WITH Safety_Check_CTE AS
(
SELECT
Fact_Unit_Safety_Checks_Wkey,
ROW_NUMBER() OVER (PARTITION BY [Dim_Unit_Wkey], [Dim_Safety_Check_Type_Wkey]
ORDER BY [Dim_Safety_Check_Date_Wkey] DESC) AS Check_No
FROM
[Pitches].[Fact_Unit_Safety_Checks]
), Last_Safety_Check_CTE AS
(
SELECT
Fact_Unit_Safety_Checks_Wkey
FROM
Safety_Check_CTE
WHERE
Check_No = 1
)
SELECT
COUNT(*)
FROM
Last_Safety_Check_CTE lc
JOIN
Pitches.Fact_Unit_Safety_Checks f ON lc.Fact_Unit_Safety_Checks_Wkey = f.Fact_Unit_Safety_Checks_Wkey
JOIN
DIM.Dim_Unit u ON f.Dim_Unit_Wkey = u.Dim_Unit_Wkey
JOIN
DIM.Dim_Safety_Check_Type t ON f.Dim_Safety_Check_Type_Wkey = t.Dim_Safety_Check_Type_Wkey
JOIN
DIM.Dim_Date d ON f.Dim_Safety_Check_Date_Wkey = d.Dim_Date_Wkey
WHERE
f.Safety_Check_Certificate_No IN ('GP/KB11007') --option (maxdop 1)
Sometimes it returns 0, 1 or 2 rows. The result should obviously be consistent.
I have ran a profile trace whilst replicating the issue and my session was the only one in the database.
I have compared the Actual execution plans and they are both the same, except the final hash match returns the differing number of rows.
I cannot replicate if I use MAXDOP 0.
In case you use my comment as the answer.
My guess is ORDER BY [Dim_Safety_Check_Date_Wkey] is not deterministic.
In the CTE's you are finding the [Fact_Unit_Safety_Checks_Wkey] that's associated with the most resent row for any given [Dim_Unit_Wkey], [Dim_Safety_Check_Type_Wkey] combination... With no regard for weather or not [Safety_Check_Certificate_No] is equal to 'GP/KB11007'.
Then, in the outer query, you are filtering results based on [Safety_Check_Certificate_No] = 'GP/KB11007'.
So, unless the most recent [Fact_Unit_Safety_Checks_Wkey] happens to have [Safety_Check_Certificate_No] = 'GP/KB11007', the data is going to be filtered out.
Sorry for the poor title. I wasn't sure how to describe my problem. I've written a query that returns about 23,000 records. A lot of those records have similar information and I want to only select the records with the maximum of the field dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength. I've tried grouping by all of the other columns being selected, but it doesn't appear to work correctly. I don't fully understand SQL, especially the max and group functions. I can do simple max functions when I only want or need to select one thing. I don't understand how it works when I want to select a bunch of other data. Below is the query.
SELECT
dbo.tblmeterinfo.fldMeterSerialNumber AS "MOP_FNP_Meter",
dbo.tblMsgsOnAir_Type8.fldRBuddyId AS "MOP_FNP_FNID",
dbo.TBLMETERMAINT.fldmeterid AS "Meter_ID_Helped",
dbo.tblMsgsOnAir_Type8.fldCBuddyId AS "FNID_Helped",
dbo.fn_dt(dbo.tblMsgsOnAir_Type8.fldRBuddyToi) AS "TOI",
dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength AS "Sig_Str",
dbo.TBLSAWN_CIS_INFO.SML AS "Buddy_SML",
dbo.TBLMETERLIST.fldaddress AS "Buddy_Address",
dbo.TBLSAWNGISCOORD.X_COORD AS "X_Coord",
dbo.TBLSAWNGISCOORD.Y_COORD AS "Y_Coord"
FROM dbo.tblMsgsOnAir_Type8
LEFT OUTER JOIN dbo.TBLMETERLIST
ON (dbo.TBLMETERLIST.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyId)
LEFT OUTER JOIN dbo.TBLMETERMAINT
ON (dbo.TBLMETERMAINT.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyID)
LEFT OUTER JOIN dbo.TBLSAWN_CIS_INFO
ON (dbo.TBLSAWN_CIS_INFO.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyId)
LEFT OUTER JOIN dbo.TBLSAWNGISCOORD
ON (dbo.TBLSAWNGISCOORD.SRV_MAP_LOC = dbo.TBLSAWN_CIS_INFO.SML)
LEFT OUTER JOIN dbo.tblmeterinfo
ON (dbo.tblmeterinfo.fldRepId = dbo.tblMsgsOnAir_Type8.fldRBuddyId)
WHERE dbo.tblMsgsOnAir_Type8.fldRBuddyId IN (SELECT
dbo.tblSAWN_FNPmap.Repid
FROM dbo.tblSAWN_FNPmap)
AND dbo.TBLMETERMAINT.fldmeterid IS NOT NULL
The query below is simple and does what I want, but doesn't get all of the other field. This query only returns 617 records. I would like the above query to return 617 records, but include all of the other information I've selected.
SELECT
dbo.TBLMETERMAINT.fldmeterid AS "Meter_ID_Helped",
MAX(dbo.tblMsgsOnAir_Type8.fldBuddyLinkSigStrength) AS "Max_Sig"
FROM dbo.tblMsgsOnAir_Type8
LEFT OUTER JOIN dbo.TBLMETERMAINT
ON (dbo.TBLMETERMAINT.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyID)
WHERE dbo.tblMsgsOnAir_Type8.fldRBuddyId IN (SELECT
dbo.tblSAWN_FNPmap.Repid
FROM dbo.tblSAWN_FNPmap)
AND dbo.TBLMETERMAINT.fldmeterid IS NOT NULL
GROUP BY dbo.TBLMETERMAINT.fldmeterid
Probably row_number() to the rescue. You can use it to find the best records in a set, with a grouping by some subset or other. Something like
select *
from ....
where row_number over (partition by id order by fldBuddyLinkSigStrength) = 1
So SQL Server assigns a row number within the groups. Each record will be sub-grouped by id, in this case, and given 1 if it's the best strength, 2 if it's next, etc.
If you are getting duplicates have you tried using SELECT DISTINCT?
Basically how Max works is that it will select the highest value in the group.
So if you have a table:
ID | VALUE
1 | 10
1 | 7
1 | 9
2 | 6
2 | 8
And do
SELECT ID, MAX(VALUE)
FROM TABLE
GROUP BY ID
You'll get the max value per ID
ID | VALUE
1 | 10
2 | 8
If you want to get the Max while not grouping the result then you can do the group in a subselect
SELECT ID, VALUE, MAX_VALUE etc etc
FROM TABLE
JOIN ( SELECT ID, MAX(VALUE) AS MAX_VALUE FROM TABLE GROUP BY ID) as MAX ON MAX.ID = TABLE.ID
Without knowing your table structures in more detail I can't be sure this is the best way, but here's something that should work. Use the 2nd query as the left side of a left join, to pick up the extra columns:
select a.*
from (<your 2nd query>) a
left join dbo.TBLMETERLIST
on (a.FLDREPID = dbo.tblMsgsOnAir_Type8.fldCBuddyId)
left join <next table> ...
and so on. You'll also have to left join on dbo.tblMsgsOnAir_Type8 in order to pick up the columns in that table, so that's one additional left join beyond what your first query does. By the way, it's a good idea to post code here laid out so it's readable; it makes it a lot easier for others to understand.
I have a table in SQL, Employee_Details, having three columns, Name, Age and Salary. I came across this query to select the highest salary from the table which goes like this.
SELECT *
FROM Employee_Details e
WHERE 0 = (
SELECT count(DISTINCT Salary)
FROM Employee_Details
WHERE Salary > e.Salary
)
I have no idea about what the '0' signifies. Could anyone please give me an idea.
It's just a condition that says that the count from the Employee_Details table in the inner SELECT query must be 0 (no one can have a higher salary than the Employee selected in the outer SELECT)
The approach to do it this way seems a bit odd to me..... I would probably have used something like this:
SELECT (columns)
FROM dbo.Employee_Details e
WHERE e.Salary = (SELECT MAX(Salary) FROM dbo.Employee_Details)
which should produce the same result - only it seems a lot clearer to me what you're trying to achieve.
Get all from table Employee_details where count of salary is 0
Your query could be written as SELECT TOP 1 WITH TIES * FROM Employee_Details e ORDER BY Salary DESC (in T-SQL dialect). Condition in original query checks if the number of distinct values of Salary greater than Salary value in e is zero (i.e. there are no rows with greater Salary).