Basic HTML Version

|  | Table of Contents |  | View Full Version

Page 51 - Modular_V2.0_SQL_Flipbook
P. 51

    5                                                  ADVANCED FEATURES

                                                                                                    OF MYSQL

                             Your Aim

                            to learn about:
                                      Subqueries                             Joins
                                       Views                                   Index

                     This chapter covers important MySQL features: subqueries, joins, views, and indexes. These concepts
                     help in managing and retrieving data efficiently from databases. Understanding these features will
                     improve your ability to write complex queries and work with multiple tables. This knowledge is
                     essential for developing better database applications.

                         SUBQUERIES

                     A subquery can be defined as a query within another query. It can be embedded within various
                     clauses of the main query, such as the WHERE, HAVING, or FROM clause. A subquery helps retrieve
                     data that will be used by the main query.

                     Syntax:
                         SELECT column1, column2
                         FROM table1
                         WHERE column1 = (SELECT column1 FROM table2 WHERE condition);

                     For example, consider the following Table - STUDENTS
                                                                                                              Minimum value
                                                               Table-STUDENTS                                   of result set

                                    Stu_id        Stu_name       Subject_group           DOB             Age
                                     101        Rahim           Arts                 2000-10-10           22
                                     102        Raja            Commerce             1999-01-08           23
                                     103        Rita            Arts                 2001-03-12           21
                                     104        Rani            Science              2002-04-01           20
                                     105        Riya            Science               2003-05-18          24

                         SELECT * FROM STUDENTS WHERE Age = (SELECT MIN(Age) FROM STUDENTS);
                     The above query will extract the records that have the minimum value in the given dataset and

                     display the details of those records that meet the criteria.

                                                                                                                         49
                                                                                            Advanced Features of MySQL

| 46 47 48 49 50 51 52 53 54 55 56 |