SQL LAG() is a window function that provides access to a row at a specified physical offset which comes before the current row. In other words, by using the LAG() function, from the current row, you can access data of the previous row, or from the second row before the current row, or from the third row before current row, and so on.

Nov 21, 2024 · The LAG() function in SQL is a powerful window function that allows you to retrieve the value of a column from the previous row in the result set. It is commonly used for tasks like calculating differences between rows, tracking trends, and comparing data within specific partitions.

Dec 23, 2024 · LAG provides access to a row at a given physical offset that comes before the current row. Use this analytic function in a SELECT statement to compare values in the current row with values in a previous row. Transact-SQL syntax conventions. OVER ( [ partition_by_clause ] order_by_clause ) .

Oct 15, 2019 · This article gives an overview of the SQL Lag function and its comparison with the SQL Lead function. We use a Lag () function to access previous rows data as per defined offset value. It is a window function available from SQL Server 2012 onwards. It …

Jul 5, 2024 · The Short Answer: What is the LAG () Function? The LAG() function is one of SQL’s window functions that allows you to create a new column that accesses a previous row from another column. It gets its name from the fact that each row in the new column you create would be lagging to fetch a value from a preceding row in the other column you specify.

Jun 11, 2024 · What Does the LAG () Function Do? The LAG () function – one of SQL’s window functions – is an important tool for planning and trend analysis. In this article, I’ll demonstrate how to include SQL LAG () in your queries using a few real-world examples.

Mar 3, 2024 · In diving deeper into the lag function in SQL, I’ve found it to be a remarkable tool for analysis and data comparison. The lag function allows me to look back at data from previous rows without having to perform complex self-joins or subqueries.

Jan 17, 2025 · The LAG function in SQL is a window function that allows you to access data from a previous row in your result set without using self-joins. It’s particularly useful for comparing current and previous row values, analyzing trends, and performing time-based calculations. The basic syntax of the LAG function is: Let’s break down the parameters:

In the following SQL lag example, we can see the use of this function to retrieve the previous invoice date field of a customer. The function is used in a single field (column) and the format looks like this: LAG ( <field_name>, offset ) OVER ( PARTITION BY <grouping_field> ORDER BY <field_name>) AS PreviousValue.

Mar 15, 2025 · Window functions in SQL are a powerful feature that allows you to perform advanced data analysis and manipulation without the need for complex self-joins or subqueries. ... Advanced Window Function Usage. Now, let’s use the LAG and LEAD functions to compare each employee’s salary with the previous and next employee in their department ...