KET SYSTEMS Interview Questions and Answers

To add a column without using create, you can use the ALTER TABLE statement.

• Use the ALTER TABLE statement to add a new column to an existing table

• Specify the table name and the new column name, data type, and any other constraints

• Example: ALTER TABLE table_name ADD column_name data_type;

Views are virtual tables that are based on the result of a query. They provide a way to simplify complex queries and restrict access to data.

• Views are created by selecting columns from one or more tables and can include joins, filters, and calculations.

• Unlike tables, views do not store data physically, but rather retrieve it dynamically from the underlying tables.

• Views can be used to present a subset of data to users, hide sensitive information, or simplify complex queries.

• Ta...read more

Indices are values that point to specific data within a data structure. They are used to access and manipulate data efficiently.

• Indices are commonly used in arrays to access specific elements.

• They can also be used in databases to improve search performance.

• Indices can be created on columns in a table to speed up queries.

• In programming, indices are often used in loops to iterate over data structures.

• Indices can also be used in mathematical operations, such as calculating the a...read more

Tomcat server is a Java-based web server that is used to serve Java Servlets and JSP pages.

• Tomcat is an open-source web server and servlet container

• It is used to deploy Java web applications

• It supports Java Servlet, JavaServer Pages (JSP), Java Expression Language (EL), and WebSocket technologies

• It can be used as a standalone server or integrated with other web servers like Apache

• It provides a web management interface for easy configuration and deployment

A table with 3-4 columns is created to store and organize data in a structured manner.

• Columns represent different attributes or properties of the data.

• Each row in the table represents a unique record or entry.

• Columns can have different data types such as text, numbers, dates, etc.

• Primary key column can be used to uniquely identify each record.

• Foreign key columns can establish relationships between tables.

• Example: A table for customer data may have columns like 'ID', 'Name', '...read more

Left outer join is used to combine all rows from the left table with matching rows from the right table.

• Use the LEFT JOIN keyword to perform a left outer join

• The syntax is: SELECT column_name(s) FROM table1 LEFT JOIN table2 ON table1.column_name = table2.column_name

• If there is no match in the right table, NULL values are returned

• Example: SELECT customers.name, orders.order_id FROM customers LEFT JOIN orders ON customers.customer_id = orders.customer_id;