Course

## Associate Data Engineer in SQL

Gain practical knowledge in ETL, SQL, and data warehousing for data engineering.

### What is the difference between LAG() and LEAD() functions?

### Can the LAG() function be used to do year-on-year analysis with monthly datasets?

### Is it mandatory to use ORDER BY in the LAG() statement?

### Can the LAG() function follow the sequence of multiple columns at once?

### What is the most critical performance optimization measure that should be taken when using the `LAG()` function?

### Is the `LAG()` function syntax different across SQL Server, MySQL, Oracle and other RDBMSs?

Topics

Learn SQL with DataCamp

2 hr

881.7K

Course

### Introduction to SQL Server

4 hr

148.8K

Course

### Introduction to Oracle SQL

4 hr

12.7K

See More

RelatedSee MoreSee More

tutorial

### Aggregate Functions in SQL

Learn how to use aggregate functions for summarizing results and gaining useful insights about data in SQL.

Sayak Paul

9 min

tutorial

### SQL SUM() Function Explained

Discover the power of the SQL SUM() function for data aggregation. Learn how to implement rolling sums, cumulative sums, and sum multiple columns effectively.

Allan Ouko

8 min

tutorial

### COALESCE SQL Function

COALESCE() is one of the handiest functions in SQL. Read this tutorial to learn how to master it.

Travis Tang

4 min

tutorial

### How to Use SQL OFFSET

Master the SQL OFFSET clause. Discover how to use ORDER BY and LIMIT to return values based on position, with practical examples, including data pagination for web applications.

Allan Ouko

10 min

tutorial

### COUNT() SQL FUNCTION

COUNT() lets you count the number of rows that match certain conditions. Learn how to use it in this tutorial.

Travis Tang

3 min

tutorial

### How to Best Use the SQL LIMIT Clause

Learn the application of the SQL LIMIT clause to filter data. Master the use of the LIMIT clause in PostgreSQL and MySQL databases.

Allan Ouko

8 min