Author Archives: user

SQL – Composite Key Table of content The SQL Composite Key An SQL Composite Key is a key that can be defined on two or more columns in a table to uniquely identify any record. It can also be described as a Primary Key created on multiple columns. Composite Keys are necessary in scenarios where […]

SQL – Primary Key Table of content The SQL Primary Key The SQL Primary Key is a column (or combination of columns) that uniquely identifies each record in a database table. The Primary Key also speeds up data access and is used to establish a relationship between tables. Even though a table can only have […]

SQL – Foreign Key Table of content The SQL Foreign Key In SQL, a Foreign Key is a column in one table that matches a Primary Key in another table, allowing the two tables to be connected together. A foreign key also maintains referential integrity between two tables, making it impossible to drop the table […]