#sqlrefresher

[codingandcrafting]

SQL Refresher #1

What is a relational database management system?

A RDBMS is a collection of programs that allow you to perform operations not limited to CRUD in your database. An RDBMS is a relational db, which means all the data is organized into a table-like structure with rows and columns.

2. What is a table? What is a field? What is a record or row? What is a column?

A table is a database object. Data is stored in tables. A field is a data entity. A record is an individual entry in a table. A column is a vertical entity that includes all the data of a field inside a table.

For example, if I have a customer table that is populated with data for age, salary, name, address, ssn numbers, id, dob, etc.

A record would be an individual row of data.

The fields are age, salary, name... etc.

A column contains all the data of a specific field, such as all the names or all the ages in the customer table.

[codingandcrafting]

SQL refresher

I started working on an SQL refresher for a Jr.SQL developer position. Just one mock interview made me realize how under prepared I was for an actual interview, granted I chose to go into this interview blind. My interviewer also mentioned that I cannot just memorize terms but I need to be able to teach the interviewer like they are 5 and provide examples.

Example questions I was asked are:

What is a primary and foreign key?

What is the difference between an inner and outer join?

Although now, I can look at these terms and feel confident. During the interview, I completely drew a blank and failed to articulate on simple questions like these.

I decided to go through the top 115 SQL Interview Questions

What is a relational database management system?

An RDBMS is a collection of programs that allow you to create, update, delete, and overall