SQL Flashcards
What is the left outer join and the right outer join in SQL?
Left outer join returns entire results from the left table along with the matched records from the right table. Right outer join is the opposite of this
What does it mean to truncate data?
To delete the data but not the table itself
What are primary keys and foreign keys?
Primary key - the unique identifier for each row of data stored in a database
Foreign key - a column or a group of columns in a relational database that describes how two tables are linked to each other
What is a table in SQL?
Tables are database objects that contain all the data in a database.
What is a database?
A SQL database is a collection of tables that stores a specific set of structured data
What are the different types of join?
Inner join, left outer join, right outer join, full outer join
What is data normalisation?
Normalization is the process to eliminate data redundancy and enhance data integrity in the table. Normalization also helps to organize the data in the database. It is a multi-step process that sets the data into tabular form and removes the duplicated data from the relational tables
What is the difference between unique key, foreign key and primary key?
primary - cannot be NULL, every row has its own primary key, used to relate tables together
foreign - a field in a table that’s a unique key in another table, used to link relational databases together
unique - can be NULL, tables may have more than one unique constraint, something like a student ID number
How can you fetch data from a table?
By using the SELECT statement
How can you use a join table to fetch data from multiple tables?
SELECT *
FROM
JOIN ON primary/foreign keys
What are SQL triggers?
A trigger is a special type of procedure that automatically runs when an event occurs in the database server. DML triggers run when a user tries to modify data through a data manipulation language (DML) event. DML events are INSERT, UPDATE, or DELETE statements
What command allows you to remove an entire table using SQL?
DROP command
What is big data?
The definition of big data is data that contains greater variety, arriving in increasing volumes and with more velocity. This is also known as the three Vs. (VARIETY, VOLUME, VELOCITY)
Put simply, big data is larger, more complex data sets, especially from new data sources. These data sets are so voluminous that traditional data processing software just can’t manage them. But these massive volumes of data can be used to address business problems you wouldn’t have been able to tackle before.
What is artificial intelligence?
Artificial intelligence leverages computers and machines to mimic the problem-solving and decision-making capabilities of the human mind.
What is cloud computing?
Cloud computing is the on-demand delivery of IT resources over the Internet with pay-as-you-go pricing. Instead of buying, owning, and maintaining physical data centers and servers, you can access technology services, such as computing power, storage, and databases, on an as-needed basis from a cloud provider like Amazon Web Services (AWS).
Benefits - scalability, cost savings, fast global deployment
