SQL BETWEEN vs. =: When to Use Which Operator?

SQL: BETWEEN vs. <= and >=

In SQL Server, the BETWEEN operator is equivalent to the combination of the <= and >= operators. However, there are subtle differences in functionality that may impact which one to use in specific scenarios.

BETWEEN Operator

The BETWEEN operator tests whether a specified expression falls within a range defined by two boundary values. The following query demonstrates its use:

SELECT EventId, EventName
FROM EventMaster
WHERE EventDate BETWEEN '10/15/2009' AND '10/18/2009'

This query will return all events where the EventDate column is greater than or equal to '10/15/2009' and less than or equal to '10/18/2009'. Both boundary values are inclusive, meaning events occurring on October 15th and 18th will be included.

<= and >= Operators

These operators can be combined to achieve the same functionality as BETWEEN. The following query is equivalent to the one above:

SELECT EventId, EventName
FROM EventMaster
WHERE EventDate >= '10/15/2009'
  AND EventDate <= '10/18/2009'

However, the <= and >= operators offer more flexibility when dealing with corner cases. For example, you can exclude either of the boundary values by using < or > instead.

Choice Considerations

• When to use BETWEEN: Use BETWEEN when you want to include both boundary values in the result.
• When to use <= and >=: Use <= and >= when you need to exclude one or both boundary values, or when you need to use the < or > operators.
• Dealing with DATETIME: When working with DATETIME values, note that the comparison includes the time component. Specify time boundaries explicitly to ensure accurate results.

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