Getting the minimum of two values in SQL

This works for up to 5 dates and handles nulls. Just couldn't get it to work as an Inline function.

CREATE FUNCTION dbo.MinDate(@Date1 datetime = Null,
@Date2 datetime = Null,
@Date3 datetime = Null,
@Date4 datetime = Null,
@Date5 datetime = Null)
RETURNS Datetime AS
BEGIN
--USAGE select dbo.MinDate('20120405',null,null,'20110305',null)
DECLARE @Output datetime;

WITH Datelist_CTE(DT)
AS (
SELECT @Date1 AS DT WHERE @Date1 is not NULL UNION
SELECT @Date2 AS DT WHERE @Date2 is not NULL UNION
SELECT @Date3 AS DT WHERE @Date3 is not NULL UNION
SELECT @Date4 AS DT WHERE @Date4 is not NULL UNION
SELECT @Date5 AS DT WHERE @Date5 is not NULL
)
Select @Output=Min(DT) FROM Datelist_CTE;

RETURN @Output;
END;

```SQL
SELECT (WHEN first > second THEN second ELSE first END) the_minimal FROM table
```

For SQL Server 2022+ (or MySQL or PostgreSQL 9.3+), a better way is to use the `LEAST` and `GREATEST` functions.

SELECT GREATEST(A.date0, B.date0) AS date0,
LEAST(A.date1, B.date1, B.date2) AS date1
FROM A, B
WHERE B.x = A.x

With:

- `GREATEST(value [, ...])` : Returns the **largest** (maximum-valued) argument from values provided
- `LEAST(value [, ...])` Returns the **smallest** (minimum-valued) argument from values provided


Documentation links :

- MySQL

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- Postgres

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- SQL Server

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