0 AD LAG HOW TO

The following statement uses the LAG() function to return YoY sales performance of every salesman: WITH cte_sales ( The following picture shows the result: B) Using Oracle LAG() function over partitions example To calculate year over year sales performance of the salesman id 62, you can use a common table expression as shown in the following query: WITH cte_sales (ĬASE WHEN py_sales IS NULL THEN 'N/A' ELSE The first row returned NULL for the py_sales column because there was no previous row of the first row. The following query uses the LEAD() function to return sales and the previous year’s sales of the salesman id 62: SELECT SELECTĬode language: SQL (Structured Query Language) ( sql ) A) Using Oracle LEAD() function over a result set example We will reuse the salesman_performance view created in the LEAD() function tutorial for the demonstration. Similar to the LEAD() function, the LAG() function is very useful for calculating the difference between the values of current and previous rows. The order_by_clause clause specifies the order of the rows in each partition to which the LAG() function is applied. By default, the function treats the whole result set as a single partition. The query_partition_clause clause divides rows into partitions to which the LAG() function is applied. If you omit default, then the function returns NULL. If the offset goes beyond the scope of the partition, the function returns the default. Is the number of rows that you want to backward from the current row. Is a scalar expression evaluated against the value of the row at a given offset prior to the current row. The following illustrates the syntax of the LAG() function: LAG(expression )Ĭode language: SQL (Structured Query Language) ( sql ) Oracle LAG() is an analytic function that allows you to access the row at a given offset prior to the current row without using a self-join.

0 AD LAG HOW TO

Summary: in this tutorial, you will learn how to access the row at a given offset prior to the current row using Oracle LAG() function.

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