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SQL Sub-Queries explained

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  Sub-Query  A sub-query is a query that is used within another query to retrieve data that will be used to manipulate the result of the main query. Here the output of inner query will be the input for outer query.It is also known as nested query or inner query. There are 3 main types of sub-query: - 1. Single-row sub-query: - A single row sub-query is a query in which inner query returns(or output) only row of data which  will be provided as an input to the outer query. To pass output of inner query output to outer query input we use '=' operator.   2. Multi-row sub-query: - A multi-row sub-query is a query where we get multiple output from inner query and those output will be passed as input to the outer query. To pass output of inner query output to outer query input we use 'IN' operator. 3. Co-related sub-query: - Co-related sub-query is a query that uses values from the outer query to filter or manipulate the result of the sub-query. It used to retrieve data tha...
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DBMS Tools

 There are many different DBMS system are available in market, each has it's own feature and limitations. Some of the most common DBMS software are:-  Oracle database, MySQL, Microsoft SQL server, Mongo DB, IBM DB2, PostgreSQL, Cassandra, Couchbase etc... Today we will be discussing about Oracle database. It is most commonly used for learning purpose among students and professionals. Oracle 10g: - It was released in 2003 by Oracle corporation. Features:  Grid Computing: Oracle 10g introduced the concept of grid computing, which allows multiple computers to work together to solve complex problems. This is like when you and your friends work together on a big project, each doing a different part of the work, to get it done faster and better. Real Application Clusters (RAC): Oracle 10g allows multiple instances of the Oracle database to run on a cluster of servers, providing scalability, availability, and performance benefits. This is like having many people working toge...
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DBMS Introduction

  Database : A database is an organized collection of data that is stored and managed on a computer system. Databases are designed to make it easy to store, retrieve, and manage large amounts of data quickly and efficiently.A database typically consists of one or more tables. Each table contains information about a specific type of data, and the rows represent individual records or entries in that table.   Types Of Database : Hierarchical Databases:- Developed in early 1960s.These are databases that organize data in a tree-like structure, with parent-child relationships. Relational Databases:- Most Popular database and developed in 1970's.These are databases that store data in a tabular format, with rows and columns. Non-Relational Databases:- Non-relational management systems are commonly referred to as   NoSQL databases . This type of database matured due to increasingly complex modern web applications. Object oriented databases:- These are databases that store data as...
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