How Can I Find the Maximum Value Across Multiple Columns in SQL?

Finding the Largest Value Across Multiple Columns in SQL

Database tables often contain multiple columns with numerical or date values. Sometimes, you need to find the single largest value across these columns – for instance, the most recent date from several date fields.

SQL's MAX function offers a solution. This approach provides a clear result set:

<code class="language-sql">SELECT
  [Number],
  (
    SELECT
      MAX(v)
    FROM (
      VALUES (date1), (date2), (date3),...
    ) AS value(v)
  ) AS [Max_Value],
  [Cost]
FROM
  [TableName];</code>

This query uses a VALUES clause to create a temporary table containing the values from the multiple date columns (or other numeric columns). The outer query then uses the MAX function on this temporary table to find the largest value. The result, labeled Max_Value, is displayed alongside the Number and Cost columns.

This method leverages SQL Server's table value constructor to efficiently determine the maximum across multiple columns. This is particularly useful when dealing with numerous columns.

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