Inconsistent dependency refers to the difficulty of accessing particular data as the path to reach the data may be missing or broken. Inconsistent dependency will leads users to search the data in the wrong table which will afterward give the error as an output.

Denormalization is used to access the data from higher or lower normal form of database. It also processes redundancy into a table by incorporating data from the related tables. Denormalization adds required redundant term into the tables so that we can avoid using complex joins and many other complex operations. Denormalization doesn?t mean that normalization will not be done, but the denormalization process takes place after the normalization process.

Operators are the special keywords or special characters reserved for performing particular operations and are used in the SQL queries. There is three type of operators used in SQL:

1. Arithmetic operators: addition (+), subtraction (-), multiplication (*), division (/), etc.
2. Logical operators: ALL, AND, ANY, ISNULL, EXISTS, BETWEEN, IN, LIKE, NOT, OR, UNIQUE.
3. Comparison operator: =, !=, <>, <, >, <=, >=, !<, !>

A view is a virtual table which contains a subset of data within a table. Views are not originally present, and it takes less space to store. A view can have data from one or more tables combined, and it depends on the relationship. Views are used to apply security mechanism in the SQL Server. The view of the database is the searchable object we can use a query to search the view as we use for the table.

SQL indexes are the medium of reducing the cost of the query as the high cost of the query will lead to the fall in the performance of the query. An index is used to increase the performance and allow faster retrieval of records from the table. Indexing reduces the number of data pages we need to visit to find a particular data page. Indexing also has a unique value that means that the index cannot be duplicated. An index creates an entry for each value, and it will be faster to retrieve data. For example, suppose you have a book which carries the details of the countries, and you want to find out the information about India than why you will go through every page of that book you could directly go to the index, and then from index you can go to that particular page where all the information about India is given.

There are three types of Indexes in SQL:

• Unique Index
• Clustered Index
• NonClustered Index
• Bit-Map index
• Normal index
• Composite index
• B-tree index
• function based index

Unique Index:

For creating a unique index, the user has to check the data in the column because the unique indexes are used when any column of the table has unique values. This indexing does not allow the field to have duplicate values if the column is unique indexed. A unique index can be applied automatically when a primary key is defined.

Clustered Index:

The clustered index is used to reorder the physical order of the table and search based on the key values. Each table can have only one clustered index. The Clustered index is the only index which has been automatically created when the primary key is generated. If moderate data modification needed to be done in the table then clustered indexes are preferred.

Non-Clustered Index:

The reason to create non-clustered index is searching the data. We well know that clustered indexes are created automatically primary keys are generated, but non-clustered indexes are created when multiple joins conditions and various filters are used in the query. Non-Clustered Index does not alter the physical order of the table and maintains logical order of data. Each table can have 999 non-clustered indexes.

SQL or Structured Query Language is a language which is used to communicate with a relational database. It provides a way to manipulate and create databases. On the other hand, MySQL and Microsoft's SQL Server both are relational database management systems that use SQL as their standard relational database language.

MySQL is available for free as it is open source whereas SQL server is not an open source software.