Compare Invoice Dates with LEAD/LAG

For each customer's invoice, show the previous and next invoice dates. This helps analyze purchase frequency patterns.

Write a SQL query using LEAD() and LAG() to show previous and next invoice dates for each customer.

Schema: Invoice

Schema: Customer

Requirements:

• Use LAG() to get the previous invoice date
• Use LEAD() to get the next invoice date
• Partition by CustomerId, order by InvoiceDate
• Return CustomerId, InvoiceDate, PrevInvoiceDate, NextInvoiceDate
• Limit to 20 rows

Window Function Syntax:

• LAG(column) OVER (PARTITION BY ... ORDER BY ...) - Previous row value
• LEAD(column) OVER (PARTITION BY ... ORDER BY ...) - Next row value