Answer:- SUBSTR() function is used to retrieve the portion of any column.

Answer:- To rename column: ALTER TABLE table_name CHANGE COLUMN old_column_name new_column_name column_defination.

Answer:- An index is a data structure of a MySQL table that is used to speed up the queries. It is used by the database search engine to find out the records faster. One or more fields of a table can be used as an index key. Index key can be assigned at the time of table declaration or can be assigned after creating the table. • Create INDEX: CREATE INDEX [index name] ON [table name]([column name]); • List all indexes: SHOW INDEXES FROM[table name];

Answer:- A maximum of 16 indexed columns can be created for any standard table.

Answer:- A view works as a virtual table that is used to store the query and returns a result set when it is called. An updatable view is also supported by MySQL. CREATE VIEW view_name AS SELECT column1, column2 FROM table_name WHERE condition;

Answer:- • Inner join: It is a default join. It returns records when the values match in joining tables. • Left outer join: It returns all the records from the left table based on the matched records from the right table. • Right outer join: It returns all the records from the right table based on matched records from the left table. • Full outer join: It returns all the records that match from the left or right table.

Answer:- A LIMIT clause is used with the SQL statement to retrieve a particular number of records from a table. From which record and how many records will be retrieved are defined by the LIMIT clause.

Answer:- COUNT() function is used to count the total number of records of any table.

Answer:- One of the major components of MySQL server is the storage engine for doing different types of database operations. Each database table created is based on the specific storage engine MySQL supports two types of storage engine i.e. transactional and non-transactional. InnoDB is the default storage engine of MySQL which is a transactional storage engine. MyISAM storage engine is a non-transactional storage engine.

Answer:- To display the maximum salary in SQL, you can use the inbuilt function called MAX().

Answer:- Query: SELECT DISTINCT(salary)FROM employee ORDER BY salary DESC LIMIT n-1,1 So if you want to find out the 2nd highest salary, consider the below query. SELECT DISTINCT(salary) FROM employee ORDER BY salary DESC LIMIT 1,1

Answer:- SELECT dept_id, MAX(salary) FROM employee GROUP BY dept_id;

Answer:- SELECT m.emp_name as Employee, e.emp_name as Manager FROM employee e, employee m WHERE m.manager_id =e.id;

Answer:- SELECT id, COUNT(id) from employee Group by id Having COUNT(id)>1 Order by COUNT (id) desc;