SQL –> Structured Query Language
1. Two dimensional tables are used, where a row is known as a record and each column known as a field.
2. Before starting analysis, it is advised to look at the table and understand what purpose each table has to play ( count number of unique employees, store employee phone numbers etc)
3. To avoid duplicates in the data, a unique id is created which is known as a primary key. Most used types of primary keys are SSN and Driver License number.
4. When data within a table is growing at two different speeds, the content needs to be normalised where table is split into two. With the link of a foreign key which points to the primary key, the data within the two separate tables is linked.
5. SQL deals with relational data where the meaning of “relational data” is that each field within a table is interconnected.
6. You are advised to always ask yourself how many records you are expected to have as a result to your query, to avoid making mistakes and identify errors early.