Class 12 Computer Science — Chapter 1: Querying and SQL Functions

Understand the fundamental difference between Single Row (Scalar) functions, which operate on each row individually, and Aggregate (Multiple Row) functions, which perform a calculation on a set of rows to return a single summary value.

Learn to use mathematical functions to perform calculations on numeric data. This includes functions like POWER() for calculating exponents, ROUND() for rounding numbers to a specified precision, and MOD() for finding the remainder of a division.

Master the manipulation of text data using common string functions. Key functions include UCASE()/LCASE() for case conversion, MID() or SUBSTRING() for extracting parts of a string, LENGTH() to find string length, and various TRIM functions (LTRIM, RTRIM, TRIM) to remove leading/trailing spaces.

Learn to work with and extract information from date and time values. This includes getting the current timestamp with NOW(), and extracting specific parts of a date like YEAR(), MONTH(), MONTHNAME(), DAY(), and DAYNAME().

Understand the structure and relationships of the sample CARSHOWROOM database, including the purpose of the INVENTORY, CUSTOMER, SALE, and EMPLOYEE tables and the data they contain. This is the foundation for writing all queries in the chapter.

Understand how to embed single-row functions within SELECT statements to create calculated columns for display, and within UPDATE statements to modify data based on calculations, as demonstrated with the 'FinalPrice' column.

Learn how to use the GROUP BY clause to collect and arrange identical data into groups. This clause is almost always used with aggregate functions (e.g., COUNT(), SUM(), AVG()) to perform calculations on each group of records.

Understand the concept of retrieving data from two or more related tables in a single query by specifying a join condition, typically linking a primary key from one table to a foreign key in another.