How to Find the Most Recent Date Across Multiple Date Columns in SQL?

SQL multi-column date maximum value acquisition skills

When working with tables containing multiple date or timestamp columns, you need to identify the latest value for each row. This article provides a SQL solution for getting the maximum value in multiple columns, converting raw data into a more manageable format.

Problem Description

Suppose there is a table called "TableName" with the following columns: [Number], [Date1], [Date2], [Date3], and [Cost]. The goal is to convert this table into a new table that displays the following information for each row: [Number], [Most_Recent_Date], and [Cost].

Solution

In SQL Server, an effective way to get the maximum value of multiple columns is to use T-SQL and SQL Server syntax:

<code class="language-sql">SELECT [Other Fields],
  (SELECT Max(v) 
   FROM (VALUES (date1), (date2), (date3),...) AS value(v)) as [MaxDate]
FROM [YourTableName]</code>

This code uses the table value constructor "VALUES" to build a temporary table that contains the values ​​of the individual columns in the original table. The SELECT statement in parentheses calculates the maximum value of each row and assigns it to the alias "[MaxDate]". By combining this information with other fields from the original table, we get a new table with the desired output format.

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