Andritz Hydro Location India Interview Questions and Answers

The NVL() function is used to replace NULL values with a specified value.

• NVL() is commonly used in SQL queries to handle NULL values.

• It takes two arguments: the value to be checked and the replacement value.

• If the value is NULL, the function returns the replacement value.

• If the value is not NULL, the function returns the original value.

• Example: SELECT NVL(column_name, 'N/A') FROM table_name;

SQL constraints are rules that are applied to a table's columns to ensure data integrity.

• Constraints are used to enforce rules and restrictions on data in SQL tables.

• They help maintain data integrity by preventing invalid or inconsistent data from being inserted or updated.

• Common types of constraints include primary key, foreign key, unique, and check constraints.

• For example, a primary key constraint ensures that each row in a table has a unique identifier.

• Constraints can be ...read more

SQL is a programming language used for managing and manipulating relational databases.

• SQL stands for Structured Query Language.

• It is used to communicate with and manage databases.

• SQL allows users to create, modify, and retrieve data from databases.

• It is a standard language for relational database management systems (RDBMS).

• SQL is used for tasks like data insertion, deletion, updating, and querying.

• Examples of popular RDBMS that use SQL include MySQL, Oracle, and SQL Server.

Constraints are rules applied to a database table to enforce data integrity and ensure accuracy.

• Constraints define limits or conditions on the data that can be inserted, updated, or deleted in a table.

• They help maintain data consistency and prevent invalid or inconsistent data from being stored.

• Common types of constraints include primary key, foreign key, unique, not null, and check constraints.

• Examples: A primary key constraint ensures each row in a table has a unique identi...read more

Primary Key is a unique identifier for each record in a database table.

• Primary Key ensures data integrity by enforcing uniqueness and preventing duplicate records.

• It is used to establish relationships between tables in a database.

• Primary Key can be a single column or a combination of multiple columns.

• It is often used as a reference in foreign key constraints.

• Examples of Primary Keys include social security numbers, email addresses, or auto-incremented IDs.