Is there a Max function in SQL Server that takes two values like Math.Max in .NET?

Can be done in one line:

-- the following expression calculates ==> max(@val1, @val2)
SELECT 0.5 * ((@val1 + @val2) + ABS(@val1 - @val2)) 

Edit: If you're dealing with very large numbers you'll have to convert the value variables into bigint in order to avoid an integer overflow.

You'd need to make a User-Defined Function if you wanted to have syntax similar to your example, but could you do what you want to do, inline, fairly easily with a CASE statement, as the others have said.

The UDF could be something like this:

create function dbo.InlineMax(@val1 int, @val2 int)
returns int
as
begin
  if @val1 > @val2
    return @val1
  return isnull(@val2,@val1)
end

... and you would call it like so ...

SELECT o.OrderId, dbo.InlineMax(o.NegotiatedPrice, o.SuggestedPrice) 
FROM Order o

I don't think so. I wanted this the other day. The closest I got was:

SELECT
  o.OrderId,
  CASE WHEN o.NegotiatedPrice > o.SuggestedPrice THEN o.NegotiatedPrice 
     ELSE o.SuggestedPrice
  END
FROM Order o

In SQL Server 2012 or higher, you can use a combination of IIF and ISNULL (or COALESCE) to get the maximum of 2 values.
Even when 1 of them is NULL.

IIF(col1 >= col2, col1, ISNULL(col2, col1)) 

Or if you want it to return 0 when both are NULL

IIF(col1 >= col2, col1, COALESCE(col2, col1, 0)) 

Example snippet:

-- use table variable for testing purposes
declare @Order table 
(
  OrderId int primary key identity(1,1),
  NegotiatedPrice decimal(10,2),
  SuggestedPrice decimal(10,2)
);

-- Sample data
insert into @Order (NegotiatedPrice, SuggestedPrice) values
(0, 1),
(2, 1),
(3, null),
(null, 4);

-- Query
SELECT 
     o.OrderId, o.NegotiatedPrice, o.SuggestedPrice, 
     IIF(o.NegotiatedPrice >= o.SuggestedPrice, o.NegotiatedPrice, ISNULL(o.SuggestedPrice, o.NegotiatedPrice)) AS MaxPrice
FROM @Order o

Result:

OrderId NegotiatedPrice SuggestedPrice  MaxPrice
1       0,00            1,00            1,00
2       2,00            1,00            2,00
3       3,00            NULL            3,00
4       NULL            4,00            4,00

But if one needs the maximum of multiple columns?
Then I suggest a CROSS APPLY on an aggregation of the VALUES.

Example:

SELECT t.*
, ca.[Maximum]
, ca.[Minimum], ca.[Total], ca.[Average]
FROM SomeTable t
CROSS APPLY (
   SELECT 
    MAX(v.col) AS [Maximum], 
    MIN(v.col) AS [Minimum], 
    SUM(v.col) AS [Total], 
    AVG(v.col) AS [Average]
   FROM (VALUES (t.Col1), (t.Col2), (t.Col3), (t.Col4)) v(col)
) ca

This has the extra benefit that this can calculate other things at the same time.

The other answers are good, but if you have to worry about having NULL values, you may want this variant:

SELECT o.OrderId, 
   CASE WHEN ISNULL(o.NegotiatedPrice, o.SuggestedPrice) > ISNULL(o.SuggestedPrice, o.NegotiatedPrice)
        THEN ISNULL(o.NegotiatedPrice, o.SuggestedPrice)
        ELSE ISNULL(o.SuggestedPrice, o.NegotiatedPrice)
   END
FROM Order o

Try this. It can handle more than 2 values

SELECT Max(v) FROM (VALUES (1), (2), (3)) AS value(v)

SELECT o.OrderId,   
--MAX(o.NegotiatedPrice, o.SuggestedPrice)  
(SELECT MAX(v) FROM (VALUES (o.NegotiatedPrice), (o.SuggestedPrice)) AS value(v)) as ChoosenPrice  
FROM Order o

I would go with the solution provided by kcrumley Just modify it slightly to handle NULLs

create function dbo.HigherArgumentOrNull(@val1 int, @val2 int)
returns int
as
begin
  if @val1 >= @val2
    return @val1
  if @val1 < @val2
    return @val2

 return NULL
end

EDIT Modified after comment from Mark. As he correctly pointed out in 3 valued logic x > NULL or x < NULL should always return NULL. In other words unknown result.

YES, THERE IS.

T-SQL (SQL Server 2022 (16.x)) now supports GREATEST/LEAST functions:

MAX/MIN as NON-aggregate function

This is now live for Azure SQL Database and SQL Managed Instance. It will roll into the next version of SQL Server.

Logical Functions - GREATEST (Transact-SQL)

This function returns the maximum value from a list of one or more expressions.

GREATEST ( expression1 [ ,...expressionN ] ) 

So in this case:

SELECT o.OrderId, GREATEST(o.NegotiatedPrice, o.SuggestedPrice)
FROM Order o

I probably wouldn't do it this way, as it's less efficient than the already mentioned CASE constructs - unless, perhaps, you had covering indexes for both queries. Either way, it's a useful technique for similar problems:

SELECT OrderId, MAX(Price) as Price FROM (
   SELECT o.OrderId, o.NegotiatedPrice as Price FROM Order o
   UNION ALL
   SELECT o.OrderId, o.SuggestedPrice as Price FROM Order o
) as A
GROUP BY OrderId

Oops, I just posted a dupe of this question...

The answer is, there is no built in function like Oracle's Greatest, but you can achieve a similar result for 2 columns with a UDF, note, the use of sql_variant is quite important here.

create table #t (a int, b int) 

insert #t
select 1,2 union all 
select 3,4 union all
select 5,2

-- option 1 - A case statement
select case when a > b then a else b end
from #t

-- option 2 - A union statement 
select a from #t where a >= b 
union all 
select b from #t where b > a 

-- option 3 - A udf
create function dbo.GREATEST
( 
    @a as sql_variant,
    @b as sql_variant
)
returns sql_variant
begin   
    declare @max sql_variant 
    if @a is null or @b is null return null
    if @b > @a return @b  
    return @a 
end


select dbo.GREATEST(a,b)
from #t

kristof

Posted this answer:

create table #t (id int IDENTITY(1,1), a int, b int)
insert #t
select 1,2 union all
select 3,4 union all
select 5,2

select id, max(val)
from #t
    unpivot (val for col in (a, b)) as unpvt
group by id

You can do something like this:

select case when o.NegotiatedPrice > o.SuggestedPrice 
then o.NegotiatedPrice
else o.SuggestedPrice
end

SELECT o.OrderID
CASE WHEN o.NegotiatedPrice > o.SuggestedPrice THEN
 o.NegotiatedPrice
ELSE
 o.SuggestedPrice
END AS Price

Here's a case example that should handle nulls and will work with older versions of MSSQL. This is based on the inline function in one one of the popular examples:

case
  when a >= b then a
  else isnull(b,a)
end

 -- Simple way without "functions" or "IF" or "CASE"
 -- Query to select maximum value
 SELECT o.OrderId
  ,(SELECT MAX(v)
   FROM (VALUES (o.NegotiatedPrice), (o.SuggestedPrice)) AS value(v)) AS MaxValue
  FROM Order o;

select OrderId, (
    select max([Price]) from (
        select NegotiatedPrice [Price]
        union all
        select SuggestedPrice
    ) p
) from [Order]

Expanding on Xin's answer and assuming the comparison value type is INT, this approach works too:

SELECT IIF(ISNULL(@A, -2147483648) > ISNULL(@B, -2147483648), @A, @B)

This is a full test with example values:

DECLARE @A AS INT
DECLARE @B AS INT

SELECT  @A = 2, @B = 1
SELECT  IIF(ISNULL(@A, -2147483648) > ISNULL(@B, -2147483648), @A, @B)
-- 2

SELECT  @A = 2, @B = 3
SELECT  IIF(ISNULL(@A, -2147483648) > ISNULL(@B, -2147483648), @A, @B)
-- 3

SELECT  @A = 2, @B = NULL
SELECT  IIF(ISNULL(@A, -2147483648) > ISNULL(@B, -2147483648), @A, @B)
-- 2    

SELECT  @A = NULL, @B = 1
SELECT  IIF(ISNULL(@A, -2147483648) > ISNULL(@B, -2147483648), @A, @B)
-- 1

In MemSQL do the following:

-- DROP FUNCTION IF EXISTS InlineMax;
DELIMITER //
CREATE FUNCTION InlineMax(val1 INT, val2 INT) RETURNS INT AS
DECLARE
  val3 INT = 0;
BEGIN
 IF val1 > val2 THEN
   RETURN val1;
 ELSE
   RETURN val2;
 END IF; 
END //
DELIMITER ;

SELECT InlineMax(1,2) as test;

In Presto you could use use

SELECT array_max(ARRAY[o.NegotiatedPrice, o.SuggestedPrice])