When dealing with records, dates are one of the most common conditions in queries. SQL makes it possible to check whether a row matches a specific date, falls before or after a threshold, or belongs in a range.
These operations are consistent across most database engines and form the basis of time-based analysis.
What Comparing Dates Means
In SQL, comparing dates means applying an operator like =, <, or > to two date values. This tells the database whether one date is the same as, earlier than, or later than another. More advanced forms include checking if a date falls within a range or if it is missing (NULL).
Examples of Date Comparisons
Equality & Inequality
WHERE birth_date = '1995-02-18';
WHERE birth_date != '1995-02-18';
Before / After
WHERE birth_date < '1993-09-22';
WHERE birth_date >= '1993-09-22';
Range Queries
WHERE birth_date BETWEEN '1990-01-01' AND '1995-12-31';
Null Handling
WHERE birth_date IS NOT NULL;
Visual Comparison with DbVisualizer
Beyond writing queries, DbVisualizer allows you to compare table rows visually. Its “Compare Data” feature shows before–after differences, making it easier to see how updates affect records.
Best Practices
- Stick to
YYYY-MM-DDformatting. - Explicitly handle
NULLcases. - Consider whether time parts matter when comparing.
- Use logical conditions clearly when checking ranges.
FAQ
How to compare dates in SQL Server?
Use standard operators or DATEDIFF(). Always format dates consistently.
How to compare parts of dates?
Extract year, month, or day using YEAR(), MONTH(), or DATEPART().
Is DATEDIFF() useful?
Yes. It helps check differences between two dates.
Can timestamps be compared too?
Yes. All the same operators apply.
Conclusion
Date comparison in SQL is simple yet essential. By using operators, handling NULL, and following best practices, you can write queries that accurately reflect real-world conditions. Visual tools like DbVisualizer can add another layer of insight.
For further reading, read How to Compare SQL Dates article.
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