Learn Debugging SQL Course Debugging SQL Finding the root cause of common SQL query problems. Lessons in this Course Lesson 1 Debugging SQL syntax errors What to do when your query returns an error message. Start this Lesson Lesson 2 Debugging SQL query logic What to do when your query returns data that looks wrong. Start this Lesson Lesson 3 Debugging duplicated data in SQL query results What to do when your query returns data with duplicated rows or columns. Start this Lesson Lesson 4 Debugging missing data in SQL query results What to do when your query returns data that's missing rows or columns. Start this Lesson