Technical(SQL)

Question 1

What is SQL?

Answer 1

Structured Query Language is a DB computer language designed to retrieve and manage data, create and modify DB schema, etc

Question 2

What is Database?

Answer 2

Db is an organized collection of data; space for storing information

Question 3

What is Query?

Answer 3

Request to DB to retrieve info

Question 4

What is DBMS?

Answer 4

Database Management System is a software that controls organization, storage, retrieval, security and integrity of data in DB

Question 5

What is relational DB?

Answer 5

DB that stores data in separate tables, rather than putting all the data in one table

Question 6

What is Schema?

Answer 6

Logical container for DB objects that is created by user; a visual or logical representation of a relational database’s logical and visual configuration

Question 7

What is Table?

Answer 7

Set of data elements that is organized using columns (fields) and rows (records)

Question 8

What is Field?

Answer 8

A DB storage simplest unit

Question 9

What is record?

Answer 9

One row of the table, represents single structured data set in a table

Question 10

What is Report?

Answer 10

Result that you get after running query

Question 11

Name popular DBs

Answer 11

Oracle, MS SQL Server, PostgreSQL, MySQL

Question 12

What did you use SQL for?

Answer 12

Getting data for testing; saving data generated during testing activities; data verification in DB (find data, ensure data integrity, manipulate test data for specific tests); testing DBs

Question 13

What is PK?

Answer 13

Primary Key is a unique identifier assigned to every record in a table

Question 14

What is DB Normalization?

Answer 14

Process of organizing fields and tables of relationship DB to minimize redundancy and dependency including dividing large tables into smaller tables and defining relationships between them

Question 15

What is a Foreign Key (FK)?

Answer 15

Column or combination of columns that is used to establish a relationship between tables; usually not unique and always points to a primary key of related table

Question 16

How to create table in DB?

Answer 16

CREATE TABLE table_name(col_name1 data_type, col_name2 data_type, etc)

Question 17

What does DESC do?

Answer 17

DESC table_name used to verify created table or find column names and datatypes

Question 18

What is used to delete table?

Answer 18

DROP TABLE table_name

Question 19

How to add, delete, modify columns in existing table?

Answer 19

ALTER TABLE table_name
ADD col_name datatype;
ALTER TABLE table_name
DROP COLUMN col_name;
ALTER TABLE table_name
MODIFY col_name datatype

Question 20

How to add record into table?

Answer 20

INSERT INTO table_name VALUES ()

Question 21

What is Constraint?

Answer 21

Used to define data integrity (restrict values in DB); e.g.: not null constraint, unique constraint, PK constraint (not null + unique), FK constraint (values in one table matches values in another), etc

Question 22

What is UPDATE used for?

Answer 22

To change data in a table. UPDATE table_name SET col1 = val1, [col2 = val2, etc] [WHERE conditions]

Question 23

How to delete records from table?

Answer 23

DELETE FROM table WHERE conditions