How do you return 1 value per row of the max of several columns:
TableName
[Number, Date1, Date2, Date3, Cost]
I need to return something like this:
[Number, Most_Recent_Date, Cost]
Query?
This question is related to
sql
sql-server
tsql
The answer is
Above table is an employee salary table with salary1,salary2,salary3,salary4 as columns.Query below will return the max value out of four columns
select
(select Max(salval) from( values (max(salary1)),(max(salary2)),(max(salary3)),(max(Salary4)))alias(salval)) as largest_val
from EmployeeSalary
Running above query will give output as largest_val(10001)
Logic of above query is as below:
select Max(salvalue) from(values (10001),(5098),(6070),(7500))alias(salvalue)
output will be 10001
Either of the two samples below will work:
SELECT MAX(date_columns) AS max_date
FROM ( (SELECT date1 AS date_columns
FROM data_table )
UNION
( SELECT date2 AS date_columns
FROM data_table
)
UNION
( SELECT date3 AS date_columns
FROM data_table
)
) AS date_query
The second is an add-on to lassevk's answer.
SELECT MAX(MostRecentDate)
FROM ( SELECT CASE WHEN date1 >= date2
AND date1 >= date3 THEN date1
WHEN date2 >= date1
AND date2 >= date3 THEN date2
WHEN date3 >= date1
AND date3 >= date2 THEN date3
ELSE date1
END AS MostRecentDate
FROM data_table
) AS date_query
SELECT
CASE
WHEN Date1 >= Date2 AND Date1 >= Date3 THEN Date1
WHEN Date2 >= Date3 THEN Date2
ELSE Date3
END AS MostRecentDate
This is slightly easier to write out and skips evaluation steps as the case statement is evaluated in order.
Here is another nice solution for the Max functionality using T-SQL and SQL Server
SELECT [Other Fields],
(SELECT Max(v)
FROM (VALUES (date1), (date2), (date3),...) AS value(v)) as [MaxDate]
FROM [YourTableName]
Either of the two samples below will work:
SELECT MAX(date_columns) AS max_date
FROM ( (SELECT date1 AS date_columns
FROM data_table )
UNION
( SELECT date2 AS date_columns
FROM data_table
)
UNION
( SELECT date3 AS date_columns
FROM data_table
)
) AS date_query
The second is an add-on to lassevk's answer.
SELECT MAX(MostRecentDate)
FROM ( SELECT CASE WHEN date1 >= date2
AND date1 >= date3 THEN date1
WHEN date2 >= date1
AND date2 >= date3 THEN date2
WHEN date3 >= date1
AND date3 >= date2 THEN date3
ELSE date1
END AS MostRecentDate
FROM data_table
) AS date_query
Problem: choose the minimum rate value given to an entity Requirements: Agency rates can be null
[MinRateValue] =
CASE
WHEN ISNULL(FitchRating.RatingValue, 100) < = ISNULL(MoodyRating.RatingValue, 99)
AND ISNULL(FitchRating.RatingValue, 100) < = ISNULL(StandardPoorsRating.RatingValue, 99)
THEN FitchgAgency.RatingAgencyName
WHEN ISNULL(MoodyRating.RatingValue, 100) < = ISNULL(StandardPoorsRating.RatingValue , 99)
THEN MoodyAgency.RatingAgencyName
ELSE ISNULL(StandardPoorsRating.RatingValue, 'N/A')
END
Inspired by this answer from Nat
DECLARE @TableName TABLE (Number INT, Date1 DATETIME, Date2 DATETIME, Date3 DATETIME, Cost MONEY)
INSERT INTO @TableName
SELECT 1, '20000101', '20010101','20020101',100 UNION ALL
SELECT 2, '20000101', '19900101','19980101',99
SELECT Number,
Cost ,
(SELECT MAX([Date])
FROM (SELECT Date1 AS [Date]
UNION ALL
SELECT Date2
UNION ALL
SELECT Date3
)
D
)
[Most Recent Date]
FROM @TableName
If you're using MySQL, you can use
SELECT GREATEST(col1, col2 ...) FROM table
There are 3 more methods where UNPIVOT (1) is the fastest by far, followed by Simulated Unpivot (3) which is much slower than (1) but still faster than (2)
CREATE TABLE dates
(
number INT PRIMARY KEY ,
date1 DATETIME ,
date2 DATETIME ,
date3 DATETIME ,
cost INT
)
INSERT INTO dates
VALUES ( 1, '1/1/2008', '2/4/2008', '3/1/2008', 10 )
INSERT INTO dates
VALUES ( 2, '1/2/2008', '2/3/2008', '3/3/2008', 20 )
INSERT INTO dates
VALUES ( 3, '1/3/2008', '2/2/2008', '3/2/2008', 30 )
INSERT INTO dates
VALUES ( 4, '1/4/2008', '2/1/2008', '3/4/2008', 40 )
GO
Solution 1 (UNPIVOT)
SELECT number ,
MAX(dDate) maxDate ,
cost
FROM dates UNPIVOT ( dDate FOR nDate IN ( Date1, Date2,
Date3 ) ) as u
GROUP BY number ,
cost
GO
Solution 2 (Sub query per row)
SELECT number ,
( SELECT MAX(dDate) maxDate
FROM ( SELECT d.date1 AS dDate
UNION
SELECT d.date2
UNION
SELECT d.date3
) a
) MaxDate ,
Cost
FROM dates d
GO
Solution 3 (Simulated UNPIVOT)
;WITH maxD
AS ( SELECT number ,
MAX(CASE rn
WHEN 1 THEN Date1
WHEN 2 THEN date2
ELSE date3
END) AS maxDate
FROM dates a
CROSS JOIN ( SELECT 1 AS rn
UNION
SELECT 2
UNION
SELECT 3
) b
GROUP BY Number
)
SELECT dates.number ,
maxD.maxDate ,
dates.cost
FROM dates
INNER JOIN MaxD ON dates.number = maxD.number
GO
DROP TABLE dates
GO
Above table is an employee salary table with salary1,salary2,salary3,salary4 as columns.Query below will return the max value out of four columns
select
(select Max(salval) from( values (max(salary1)),(max(salary2)),(max(salary3)),(max(Salary4)))alias(salval)) as largest_val
from EmployeeSalary
Running above query will give output as largest_val(10001)
Logic of above query is as below:
select Max(salvalue) from(values (10001),(5098),(6070),(7500))alias(salvalue)
output will be 10001
here is a good solution:
CREATE function [dbo].[inLineMax] (@v1 float,@v2 float,@v3 float,@v4 float)
returns float
as
begin
declare @val float
set @val = 0
declare @TableVal table
(value float )
insert into @TableVal select @v1
insert into @TableVal select @v2
insert into @TableVal select @v3
insert into @TableVal select @v4
select @val= max(value) from @TableVal
return @val
end
If you are using SQL Server 2005, you can use the UNPIVOT feature. Here is a complete example:
create table dates
(
number int,
date1 datetime,
date2 datetime,
date3 datetime
)
insert into dates values (1, '1/1/2008', '2/4/2008', '3/1/2008')
insert into dates values (1, '1/2/2008', '2/3/2008', '3/3/2008')
insert into dates values (1, '1/3/2008', '2/2/2008', '3/2/2008')
insert into dates values (1, '1/4/2008', '2/1/2008', '3/4/2008')
select max(dateMaxes)
from (
select
(select max(date1) from dates) date1max,
(select max(date2) from dates) date2max,
(select max(date3) from dates) date3max
) myTable
unpivot (dateMaxes For fieldName In (date1max, date2max, date3max)) as tblPivot
drop table dates
Scalar Function cause all sorts of performance issues, so its better to wrap the logic into an Inline Table Valued Function if possible. This is the function I used to replace some User Defined Functions which selected the Min/Max dates from a list of upto ten dates. When tested on my dataset of 1 Million rows the Scalar Function took over 15 minutes before I killed the query the Inline TVF took 1 minute which is the same amount of time as selecting the resultset into a temporary table. To use this call the function from either a subquery in the the SELECT or a CROSS APPLY.
CREATE FUNCTION dbo.Get_Min_Max_Date
(
@Date1 datetime,
@Date2 datetime,
@Date3 datetime,
@Date4 datetime,
@Date5 datetime,
@Date6 datetime,
@Date7 datetime,
@Date8 datetime,
@Date9 datetime,
@Date10 datetime
)
RETURNS TABLE
AS
RETURN
(
SELECT Max(DateValue) Max_Date,
Min(DateValue) Min_Date
FROM (
VALUES (@Date1),
(@Date2),
(@Date3),
(@Date4),
(@Date5),
(@Date6),
(@Date7),
(@Date8),
(@Date9),
(@Date10)
) AS Dates(DateValue)
)
here is a good solution:
CREATE function [dbo].[inLineMax] (@v1 float,@v2 float,@v3 float,@v4 float)
returns float
as
begin
declare @val float
set @val = 0
declare @TableVal table
(value float )
insert into @TableVal select @v1
insert into @TableVal select @v2
insert into @TableVal select @v3
insert into @TableVal select @v4
select @val= max(value) from @TableVal
return @val
end
From SQL Server 2012 we can use IIF.
DECLARE @Date1 DATE='2014-07-03';
DECLARE @Date2 DATE='2014-07-04';
DECLARE @Date3 DATE='2014-07-05';
SELECT IIF(@Date1>@Date2,
IIF(@Date1>@Date3,@Date1,@Date3),
IIF(@Date2>@Date3,@Date2,@Date3)) AS MostRecentDate
If you are using SQL Server 2005, you can use the UNPIVOT feature. Here is a complete example:
create table dates
(
number int,
date1 datetime,
date2 datetime,
date3 datetime
)
insert into dates values (1, '1/1/2008', '2/4/2008', '3/1/2008')
insert into dates values (1, '1/2/2008', '2/3/2008', '3/3/2008')
insert into dates values (1, '1/3/2008', '2/2/2008', '3/2/2008')
insert into dates values (1, '1/4/2008', '2/1/2008', '3/4/2008')
select max(dateMaxes)
from (
select
(select max(date1) from dates) date1max,
(select max(date2) from dates) date2max,
(select max(date3) from dates) date3max
) myTable
unpivot (dateMaxes For fieldName In (date1max, date2max, date3max)) as tblPivot
drop table dates
For T-SQL (MSSQL 2008+)
SELECT
(SELECT
MAX(MyMaxName)
FROM ( VALUES
(MAX(Field1)),
(MAX(Field2))
) MyAlias(MyMaxName)
)
FROM MyTable1
Unfortunately Lasse's answer, though seemingly obvious, has a crucial flaw. It cannot handle NULL values. Any single NULL value results in Date1 being returned. Unfortunately any attempt to fix that problem tends to get extremely messy and doesn't scale to 4 or more values very nicely.
databyss's first answer looked (and is) good. However, it wasn't clear whether the answer would easily extrapolate to 3 values from a multi-table join instead of the simpler 3 values from a single table. I wanted to avoid turning such a query into a sub-query just to get the max of 3 columns, also I was pretty sure databyss's excellent idea could be cleaned up a bit.
So without further ado, here's my solution (derived from databyss's idea).
It uses cross-joins selecting constants to simulate the effect of a multi-table join. The important thing to note is that all the necessary aliases carry through correctly (which is not always the case) and this keeps the pattern quite simple and fairly scalable through additional columns.
DECLARE @v1 INT ,
@v2 INT ,
@v3 INT
--SET @v1 = 1 --Comment out SET statements to experiment with
--various combinations of NULL values
SET @v2 = 2
SET @v3 = 3
SELECT ( SELECT MAX(Vals)
FROM ( SELECT v1 AS Vals
UNION
SELECT v2
UNION
SELECT v3
) tmp
WHERE Vals IS NOT NULL -- This eliminates NULL warning
) AS MaxVal
FROM ( SELECT @v1 AS v1
) t1
CROSS JOIN ( SELECT @v2 AS v2
) t2
CROSS JOIN ( SELECT @v3 AS v3
) t3
You could create a function where you pass the dates and then add the function to the select statement like below. select Number, dbo.fxMost_Recent_Date(Date1,Date2,Date3), Cost
create FUNCTION fxMost_Recent_Date
( @Date1 smalldatetime, @Date2 smalldatetime, @Date3 smalldatetime ) RETURNS smalldatetime AS BEGIN DECLARE @Result smalldatetime
declare @MostRecent smalldatetime
set @MostRecent='1/1/1900'
if @Date1>@MostRecent begin set @MostRecent=@Date1 end
if @Date2>@MostRecent begin set @MostRecent=@Date2 end
if @Date3>@MostRecent begin set @MostRecent=@Date3 end
RETURN @MostRecent
END
I do not know if it is on SQL, etc... on M$ACCESS help there is a function called MAXA(Value1;Value2;...) that is supposed to do such.
Hope can help someone.
P.D.: Values can be columns or calculated ones, etc.
Please try using UNPIVOT:
SELECT MAX(MaxDt) MaxDt
FROM tbl
UNPIVOT
(MaxDt FOR E IN
(Date1, Date2, Date3)
)AS unpvt;
SELECT
CASE
WHEN Date1 >= Date2 AND Date1 >= Date3 THEN Date1
WHEN Date2 >= Date3 THEN Date2
ELSE Date3
END AS MostRecentDate
This is slightly easier to write out and skips evaluation steps as the case statement is evaluated in order.
For T-SQL (MSSQL 2008+)
SELECT
(SELECT
MAX(MyMaxName)
FROM ( VALUES
(MAX(Field1)),
(MAX(Field2))
) MyAlias(MyMaxName)
)
FROM MyTable1
You could create a function where you pass the dates and then add the function to the select statement like below. select Number, dbo.fxMost_Recent_Date(Date1,Date2,Date3), Cost
create FUNCTION fxMost_Recent_Date
( @Date1 smalldatetime, @Date2 smalldatetime, @Date3 smalldatetime ) RETURNS smalldatetime AS BEGIN DECLARE @Result smalldatetime
declare @MostRecent smalldatetime
set @MostRecent='1/1/1900'
if @Date1>@MostRecent begin set @MostRecent=@Date1 end
if @Date2>@MostRecent begin set @MostRecent=@Date2 end
if @Date3>@MostRecent begin set @MostRecent=@Date3 end
RETURN @MostRecent
END
Scalar Function cause all sorts of performance issues, so its better to wrap the logic into an Inline Table Valued Function if possible. This is the function I used to replace some User Defined Functions which selected the Min/Max dates from a list of upto ten dates. When tested on my dataset of 1 Million rows the Scalar Function took over 15 minutes before I killed the query the Inline TVF took 1 minute which is the same amount of time as selecting the resultset into a temporary table. To use this call the function from either a subquery in the the SELECT or a CROSS APPLY.
CREATE FUNCTION dbo.Get_Min_Max_Date
(
@Date1 datetime,
@Date2 datetime,
@Date3 datetime,
@Date4 datetime,
@Date5 datetime,
@Date6 datetime,
@Date7 datetime,
@Date8 datetime,
@Date9 datetime,
@Date10 datetime
)
RETURNS TABLE
AS
RETURN
(
SELECT Max(DateValue) Max_Date,
Min(DateValue) Min_Date
FROM (
VALUES (@Date1),
(@Date2),
(@Date3),
(@Date4),
(@Date5),
(@Date6),
(@Date7),
(@Date8),
(@Date9),
(@Date10)
) AS Dates(DateValue)
)
Another way to use CASE WHEN
SELECT CASE true
WHEN max(row1) >= max(row2) THEN CASE true WHEN max(row1) >= max(row3) THEN max(row1) ELSE max(row3) end ELSE
CASE true WHEN max(row2) >= max(row3) THEN max(row2) ELSE max(row3) END END
FROM yourTable
Here is another nice solution for the Max functionality using T-SQL and SQL Server
SELECT [Other Fields],
(SELECT Max(v)
FROM (VALUES (date1), (date2), (date3),...) AS value(v)) as [MaxDate]
FROM [YourTableName]
I prefer solutions based on case-when, my assumption is that it should have the least impact on possible performance drop compared to other possible solutions like those with cross-apply, values(), custom functions etc.
Here is the case-when version that handles null values with most of possible test cases:
SELECT
CASE
WHEN Date1 > coalesce(Date2,'0001-01-01') AND Date1 > coalesce(Date3,'0001-01-01') THEN Date1
WHEN Date2 > coalesce(Date3,'0001-01-01') THEN Date2
ELSE Date3
END AS MostRecentDate
, *
from
(values
( 1, cast('2001-01-01' as Date), cast('2002-01-01' as Date), cast('2003-01-01' as Date))
,( 2, cast('2001-01-01' as Date), cast('2003-01-01' as Date), cast('2002-01-01' as Date))
,( 3, cast('2002-01-01' as Date), cast('2001-01-01' as Date), cast('2003-01-01' as Date))
,( 4, cast('2002-01-01' as Date), cast('2003-01-01' as Date), cast('2001-01-01' as Date))
,( 5, cast('2003-01-01' as Date), cast('2001-01-01' as Date), cast('2002-01-01' as Date))
,( 6, cast('2003-01-01' as Date), cast('2002-01-01' as Date), cast('2001-01-01' as Date))
,( 11, cast(NULL as Date), cast('2002-01-01' as Date), cast('2003-01-01' as Date))
,( 12, cast(NULL as Date), cast('2003-01-01' as Date), cast('2002-01-01' as Date))
,( 13, cast('2003-01-01' as Date), cast(NULL as Date), cast('2002-01-01' as Date))
,( 14, cast('2002-01-01' as Date), cast(NULL as Date), cast('2003-01-01' as Date))
,( 15, cast('2003-01-01' as Date), cast('2002-01-01' as Date), cast(NULL as Date))
,( 16, cast('2002-01-01' as Date), cast('2003-01-01' as Date), cast(NULL as Date))
,( 21, cast('2003-01-01' as Date), cast(NULL as Date), cast(NULL as Date))
,( 22, cast(NULL as Date), cast('2003-01-01' as Date), cast(NULL as Date))
,( 23, cast(NULL as Date), cast(NULL as Date), cast('2003-01-01' as Date))
,( 31, cast(NULL as Date), cast(NULL as Date), cast(NULL as Date))
) as demoValues(id, Date1,Date2,Date3)
order by id
;
and the result is:
MostRecent id Date1 Date2 Date3
2003-01-01 1 2001-01-01 2002-01-01 2003-01-01
2003-01-01 2 2001-01-01 2003-01-01 2002-01-01
2003-01-01 3 2002-01-01 2001-01-01 2002-01-01
2003-01-01 4 2002-01-01 2003-01-01 2001-01-01
2003-01-01 5 2003-01-01 2001-01-01 2002-01-01
2003-01-01 6 2003-01-01 2002-01-01 2001-01-01
2003-01-01 11 NULL 2002-01-01 2003-01-01
2003-01-01 12 NULL 2003-01-01 2002-01-01
2003-01-01 13 2003-01-01 NULL 2002-01-01
2003-01-01 14 2002-01-01 NULL 2003-01-01
2003-01-01 15 2003-01-01 2002-01-01 NULL
2003-01-01 16 2002-01-01 2003-01-01 NULL
2003-01-01 21 2003-01-01 NULL NULL
2003-01-01 22 NULL 2003-01-01 NULL
2003-01-01 23 NULL NULL 2003-01-01
NULL 31 NULL NULL NULL
DECLARE @TableName TABLE (Number INT, Date1 DATETIME, Date2 DATETIME, Date3 DATETIME, Cost MONEY)
INSERT INTO @TableName
SELECT 1, '20000101', '20010101','20020101',100 UNION ALL
SELECT 2, '20000101', '19900101','19980101',99
SELECT Number,
Cost ,
(SELECT MAX([Date])
FROM (SELECT Date1 AS [Date]
UNION ALL
SELECT Date2
UNION ALL
SELECT Date3
)
D
)
[Most Recent Date]
FROM @TableName
If you're using MySQL, you can use
SELECT GREATEST(col1, col2 ...) FROM table
Either of the two samples below will work:
SELECT MAX(date_columns) AS max_date
FROM ( (SELECT date1 AS date_columns
FROM data_table )
UNION
( SELECT date2 AS date_columns
FROM data_table
)
UNION
( SELECT date3 AS date_columns
FROM data_table
)
) AS date_query
The second is an add-on to lassevk's answer.
SELECT MAX(MostRecentDate)
FROM ( SELECT CASE WHEN date1 >= date2
AND date1 >= date3 THEN date1
WHEN date2 >= date1
AND date2 >= date3 THEN date2
WHEN date3 >= date1
AND date3 >= date2 THEN date3
ELSE date1
END AS MostRecentDate
FROM data_table
) AS date_query
Another way to use CASE WHEN
SELECT CASE true
WHEN max(row1) >= max(row2) THEN CASE true WHEN max(row1) >= max(row3) THEN max(row1) ELSE max(row3) end ELSE
CASE true WHEN max(row2) >= max(row3) THEN max(row2) ELSE max(row3) END END
FROM yourTable
If you're using MySQL, you can use
SELECT GREATEST(col1, col2 ...) FROM table
If you are using SQL Server 2005, you can use the UNPIVOT feature. Here is a complete example:
create table dates
(
number int,
date1 datetime,
date2 datetime,
date3 datetime
)
insert into dates values (1, '1/1/2008', '2/4/2008', '3/1/2008')
insert into dates values (1, '1/2/2008', '2/3/2008', '3/3/2008')
insert into dates values (1, '1/3/2008', '2/2/2008', '3/2/2008')
insert into dates values (1, '1/4/2008', '2/1/2008', '3/4/2008')
select max(dateMaxes)
from (
select
(select max(date1) from dates) date1max,
(select max(date2) from dates) date2max,
(select max(date3) from dates) date3max
) myTable
unpivot (dateMaxes For fieldName In (date1max, date2max, date3max)) as tblPivot
drop table dates
If you're using MySQL, you can use
SELECT GREATEST(col1, col2 ...) FROM table
I prefer solutions based on case-when, my assumption is that it should have the least impact on possible performance drop compared to other possible solutions like those with cross-apply, values(), custom functions etc.
Here is the case-when version that handles null values with most of possible test cases:
SELECT
CASE
WHEN Date1 > coalesce(Date2,'0001-01-01') AND Date1 > coalesce(Date3,'0001-01-01') THEN Date1
WHEN Date2 > coalesce(Date3,'0001-01-01') THEN Date2
ELSE Date3
END AS MostRecentDate
, *
from
(values
( 1, cast('2001-01-01' as Date), cast('2002-01-01' as Date), cast('2003-01-01' as Date))
,( 2, cast('2001-01-01' as Date), cast('2003-01-01' as Date), cast('2002-01-01' as Date))
,( 3, cast('2002-01-01' as Date), cast('2001-01-01' as Date), cast('2003-01-01' as Date))
,( 4, cast('2002-01-01' as Date), cast('2003-01-01' as Date), cast('2001-01-01' as Date))
,( 5, cast('2003-01-01' as Date), cast('2001-01-01' as Date), cast('2002-01-01' as Date))
,( 6, cast('2003-01-01' as Date), cast('2002-01-01' as Date), cast('2001-01-01' as Date))
,( 11, cast(NULL as Date), cast('2002-01-01' as Date), cast('2003-01-01' as Date))
,( 12, cast(NULL as Date), cast('2003-01-01' as Date), cast('2002-01-01' as Date))
,( 13, cast('2003-01-01' as Date), cast(NULL as Date), cast('2002-01-01' as Date))
,( 14, cast('2002-01-01' as Date), cast(NULL as Date), cast('2003-01-01' as Date))
,( 15, cast('2003-01-01' as Date), cast('2002-01-01' as Date), cast(NULL as Date))
,( 16, cast('2002-01-01' as Date), cast('2003-01-01' as Date), cast(NULL as Date))
,( 21, cast('2003-01-01' as Date), cast(NULL as Date), cast(NULL as Date))
,( 22, cast(NULL as Date), cast('2003-01-01' as Date), cast(NULL as Date))
,( 23, cast(NULL as Date), cast(NULL as Date), cast('2003-01-01' as Date))
,( 31, cast(NULL as Date), cast(NULL as Date), cast(NULL as Date))
) as demoValues(id, Date1,Date2,Date3)
order by id
;
and the result is:
MostRecent id Date1 Date2 Date3
2003-01-01 1 2001-01-01 2002-01-01 2003-01-01
2003-01-01 2 2001-01-01 2003-01-01 2002-01-01
2003-01-01 3 2002-01-01 2001-01-01 2002-01-01
2003-01-01 4 2002-01-01 2003-01-01 2001-01-01
2003-01-01 5 2003-01-01 2001-01-01 2002-01-01
2003-01-01 6 2003-01-01 2002-01-01 2001-01-01
2003-01-01 11 NULL 2002-01-01 2003-01-01
2003-01-01 12 NULL 2003-01-01 2002-01-01
2003-01-01 13 2003-01-01 NULL 2002-01-01
2003-01-01 14 2002-01-01 NULL 2003-01-01
2003-01-01 15 2003-01-01 2002-01-01 NULL
2003-01-01 16 2002-01-01 2003-01-01 NULL
2003-01-01 21 2003-01-01 NULL NULL
2003-01-01 22 NULL 2003-01-01 NULL
2003-01-01 23 NULL NULL 2003-01-01
NULL 31 NULL NULL NULL
Based on the ScottPletcher's solution from http://www.experts-exchange.com/Microsoft/Development/MS-SQL-Server/Q_24204894.html I’ve created a set of functions (e.g. GetMaxOfDates3 , GetMaxOfDates13 )to find max of up to 13 Date values using UNION ALL. See T-SQL function to Get Maximum of values from the same row However I haven't considered UNPIVOT solution at the time of writing these functions
I do not know if it is on SQL, etc... on M$ACCESS help there is a function called MAXA(Value1;Value2;...) that is supposed to do such.
Hope can help someone.
P.D.: Values can be columns or calculated ones, etc.
If you are using SQL Server 2005, you can use the UNPIVOT feature. Here is a complete example:
create table dates
(
number int,
date1 datetime,
date2 datetime,
date3 datetime
)
insert into dates values (1, '1/1/2008', '2/4/2008', '3/1/2008')
insert into dates values (1, '1/2/2008', '2/3/2008', '3/3/2008')
insert into dates values (1, '1/3/2008', '2/2/2008', '3/2/2008')
insert into dates values (1, '1/4/2008', '2/1/2008', '3/4/2008')
select max(dateMaxes)
from (
select
(select max(date1) from dates) date1max,
(select max(date2) from dates) date2max,
(select max(date3) from dates) date3max
) myTable
unpivot (dateMaxes For fieldName In (date1max, date2max, date3max)) as tblPivot
drop table dates
Using CROSS APPLY (for 2005+) ....
SELECT MostRecentDate
FROM SourceTable
CROSS APPLY (SELECT MAX(d) MostRecentDate FROM (VALUES (Date1), (Date2), (Date3)) AS a(d)) md
Unfortunately Lasse's answer, though seemingly obvious, has a crucial flaw. It cannot handle NULL values. Any single NULL value results in Date1 being returned. Unfortunately any attempt to fix that problem tends to get extremely messy and doesn't scale to 4 or more values very nicely.
databyss's first answer looked (and is) good. However, it wasn't clear whether the answer would easily extrapolate to 3 values from a multi-table join instead of the simpler 3 values from a single table. I wanted to avoid turning such a query into a sub-query just to get the max of 3 columns, also I was pretty sure databyss's excellent idea could be cleaned up a bit.
So without further ado, here's my solution (derived from databyss's idea).
It uses cross-joins selecting constants to simulate the effect of a multi-table join. The important thing to note is that all the necessary aliases carry through correctly (which is not always the case) and this keeps the pattern quite simple and fairly scalable through additional columns.
DECLARE @v1 INT ,
@v2 INT ,
@v3 INT
--SET @v1 = 1 --Comment out SET statements to experiment with
--various combinations of NULL values
SET @v2 = 2
SET @v3 = 3
SELECT ( SELECT MAX(Vals)
FROM ( SELECT v1 AS Vals
UNION
SELECT v2
UNION
SELECT v3
) tmp
WHERE Vals IS NOT NULL -- This eliminates NULL warning
) AS MaxVal
FROM ( SELECT @v1 AS v1
) t1
CROSS JOIN ( SELECT @v2 AS v2
) t2
CROSS JOIN ( SELECT @v3 AS v3
) t3
From SQL Server 2012 we can use IIF.
DECLARE @Date1 DATE='2014-07-03';
DECLARE @Date2 DATE='2014-07-04';
DECLARE @Date3 DATE='2014-07-05';
SELECT IIF(@Date1>@Date2,
IIF(@Date1>@Date3,@Date1,@Date3),
IIF(@Date2>@Date3,@Date2,@Date3)) AS MostRecentDate
Either of the two samples below will work:
SELECT MAX(date_columns) AS max_date
FROM ( (SELECT date1 AS date_columns
FROM data_table )
UNION
( SELECT date2 AS date_columns
FROM data_table
)
UNION
( SELECT date3 AS date_columns
FROM data_table
)
) AS date_query
The second is an add-on to lassevk's answer.
SELECT MAX(MostRecentDate)
FROM ( SELECT CASE WHEN date1 >= date2
AND date1 >= date3 THEN date1
WHEN date2 >= date1
AND date2 >= date3 THEN date2
WHEN date3 >= date1
AND date3 >= date2 THEN date3
ELSE date1
END AS MostRecentDate
FROM data_table
) AS date_query
There are 3 more methods where UNPIVOT (1) is the fastest by far, followed by Simulated Unpivot (3) which is much slower than (1) but still faster than (2)
CREATE TABLE dates
(
number INT PRIMARY KEY ,
date1 DATETIME ,
date2 DATETIME ,
date3 DATETIME ,
cost INT
)
INSERT INTO dates
VALUES ( 1, '1/1/2008', '2/4/2008', '3/1/2008', 10 )
INSERT INTO dates
VALUES ( 2, '1/2/2008', '2/3/2008', '3/3/2008', 20 )
INSERT INTO dates
VALUES ( 3, '1/3/2008', '2/2/2008', '3/2/2008', 30 )
INSERT INTO dates
VALUES ( 4, '1/4/2008', '2/1/2008', '3/4/2008', 40 )
GO
Solution 1 (UNPIVOT)
SELECT number ,
MAX(dDate) maxDate ,
cost
FROM dates UNPIVOT ( dDate FOR nDate IN ( Date1, Date2,
Date3 ) ) as u
GROUP BY number ,
cost
GO
Solution 2 (Sub query per row)
SELECT number ,
( SELECT MAX(dDate) maxDate
FROM ( SELECT d.date1 AS dDate
UNION
SELECT d.date2
UNION
SELECT d.date3
) a
) MaxDate ,
Cost
FROM dates d
GO
Solution 3 (Simulated UNPIVOT)
;WITH maxD
AS ( SELECT number ,
MAX(CASE rn
WHEN 1 THEN Date1
WHEN 2 THEN date2
ELSE date3
END) AS maxDate
FROM dates a
CROSS JOIN ( SELECT 1 AS rn
UNION
SELECT 2
UNION
SELECT 3
) b
GROUP BY Number
)
SELECT dates.number ,
maxD.maxDate ,
dates.cost
FROM dates
INNER JOIN MaxD ON dates.number = maxD.number
GO
DROP TABLE dates
GO
Based on the ScottPletcher's solution from http://www.experts-exchange.com/Microsoft/Development/MS-SQL-Server/Q_24204894.html I’ve created a set of functions (e.g. GetMaxOfDates3 , GetMaxOfDates13 )to find max of up to 13 Date values using UNION ALL. See T-SQL function to Get Maximum of values from the same row However I haven't considered UNPIVOT solution at the time of writing these functions
Using CROSS APPLY (for 2005+) ....
SELECT MostRecentDate
FROM SourceTable
CROSS APPLY (SELECT MAX(d) MostRecentDate FROM (VALUES (Date1), (Date2), (Date3)) AS a(d)) md
Please try using UNPIVOT:
SELECT MAX(MaxDt) MaxDt
FROM tbl
UNPIVOT
(MaxDt FOR E IN
(Date1, Date2, Date3)
)AS unpvt;
Source: Stackoverflow.com