SQL LAG Function Explained: Purpose & Uses

The lag function is a type of window function used in SQL to retrieve the value of a specific row before the current row. It can be used to calculate the difference or ratio between the current row and the previous row. The lag function allows for specifying the offset of the previous row to be retrieved, with a default value of 1 if not specified. It is often used in time series analysis and comparing data from adjacent rows.