# DataBase
schema is a logical blueprint or structure that defines the organization, design, and relationship between different tables and entities in a database. It represents the overall framework of the database, including tables, columns, data types, constraints, and relationships.
A schema is used to organize and represent data in a structured and consistent manner. It provides a way to define the structure of the database and ensure data integrity by enforcing constraints and relationships. By using a schema, developers and administrators can easily understand and manage the database, perform data manipulation, and retrieve information efficiently.
A database schema typically consists of tables, columns, data types, constraints, and relationships. Tables represent the entities or objects being stored, columns define the attributes or properties of those entities, data types specify the type of data each column can hold, constraints define rules and restrictions on the data, and relationships define the associations between tables.
There are different types of database keys, including:
Primary Key: It is a unique identifier for a record in a table. It uniquely identifies each row in the table and ensures data integrity. There can be only one primary key per table.
Foreign Key: It is a field in a table that refers to the primary key of another table. It establishes a relationship between two tables by enforcing referential integrity. Foreign keys help maintain data consistency and enable the implementation of various types of relationships between tables.
Composite Key: It is a key that consists of multiple columns in a table. The combination of these columns must be unique to identify a record. Composite keys are useful when a single column cannot uniquely identify a record, but the combination of multiple columns can.
It is a unique identifier for a record in a table. It uniquely identifies each row in the table and ensures data integrity. There can be only one primary key per table.
It is a field in a table that refers to the primary key of another table. It establishes a relationship between two tables by enforcing referential integrity. Foreign keys help maintain data consistency and enable the implementation of various types of relationships between tables.
It is a key that consists of multiple columns in a table. The combination of these columns must be unique to identify a record. Composite keys are useful when a single column cannot uniquely identify a record, but the combination of multiple columns can.
depends on the specific requirements of the database design and the relationships between tables.
relationships define the associations or connections between tables. These relationships establish dependencies and constraints between tables, enabling data integrity and allowing data to be retrieved and manipulated in meaningful ways.
1:1 relationship refers to a relationship where each record in one table is associated with exactly one record in another table, and vice versa. It means that the two tables have a one-to-one correspondence, and the relationship is usually defined using primary and foreign keys.
Many:Many relationship, also known as a many-to-many relationship, is a relationship where each record in one table can be associated with multiple records in another table, and vice versa. It means that multiple records from one table can be related to multiple records in another table. To implement a many-to-many relationship, a join table is typically used, which contains the primary keys from both tables.
1:Many or Many:1 relationship, also known as a one-to-many relationship, is a relationship where each record in one table can be associated with multiple records in another table, but each record in the other table is associated with only one record in the first table. This relationship is often implemented using a foreign key in the “many” table that refers to the primary key in the “one” table.
## Things I want to know more about
diving deeper into databases in C# programming