Dbs101_flippedclass3
Topic : Null Values in SQL and Set Operations in SQL
Its about the null values in SQL and set operations in SQL, the null values in SQL stands for unknown or missing data. It’s like a blank space in a table column or it is not a single value; it isn’t the same as zero or an empty string. In searches and calculations, you can apply NULL to handle missing data, and there are certain ways for handling it. Understanding NULL is essential for effectively managing data in databases. The aggregate functions like COUNT(), SUM(), and AVG(), deal with the null values which typically ignore NULL values in calculations. They only consider non-NULL values unless instructed otherwise and wanted to include NULL values, you’ll need to handle them explicitly using functions like COUNT(*), ISNULL(), or COALESCE().
Set operators in SQL are used to combine or compare the results of two or more SELECT statements into a single result set. These operators include UNION, INTERSECT, and EXCEPT (or MINUS in some SQL dialects).
- UNION combines the results and eliminates duplicate rows.
- UNION ALL combines all results, including duplicates.
- INTERSECT returns only rows that appear in both result sets, removing duplicates.
- EXCEPT (or MINUS) returns rows from the first query that are not in the second query, also removing duplicates.
These operators are powerful tools for data manipulation and analysis, allowing for flexible querying and data combination without the need for joining tables
The flipped class had the same instruction as our first flipped class where the students were divided into four groups with 6 or 7 members each. There will be two expert groups having two different topics. First 30 minutes is given for reading time, next 30 minutes for discussion time and last 30 minutes, we have to return to our home group to explain our own ideas to other group members.
So, my expert group was 2 with the topic ‘Null values in SQL’, I just read the reading materials given in the instructions for the first 30 minutes then, the next 30 minutes our group just shared our own ideas or perceptive and added some points on our topic.At last, we moved to our home group, did a short presentation in our own language and also gave some simple examples to make it more understandable.
2 hours is too long for the flipped class, maybe 1 hour 30 minutes will be enough.