A date-based JOIN matches records using date or timestamp conditions in addition to normal relationship columns.
Many business relationships depend on when an event occurred, not only on an ID.
Match a transaction to the employee assignment that was active on the transaction date.
SELECT
t.TransactionID,
t.TransactionDate,
e.EmployeeName
FROM Transactions t
INNER JOIN EmployeeAssignments a
ON t.EmployeeID = a.EmployeeID
AND t.TransactionDate >= a.StartDate
AND t.TransactionDate < a.EndDate
INNER JOIN Employees e
ON a.EmployeeID = e.EmployeeID;Used in historical reporting, employee assignments, pricing, contracts, exchange rates, and financial analysis.
- Dates can be part of JOIN conditions.
- Date ranges can define valid relationships.
- Time-based relationships are common in business systems.
- Boundary conditions must be tested carefully.
- Date data types should be compatible.
Why use dates in a JOIN condition?
Dates can determine whether a relationship was valid during a specific period.
Where are date-based JOINs commonly used?
They are common in historical reporting, contracts, employee assignments, pricing, and financial analysis.