Identify types of SQL statement

Question 1

What are common relational database management systems that use SQL?

Answer 1

• Microsoft SQL server
• MySQL
• PostgreSQL
• MariaDB
• Oracle

Question 2

What is SQL?

Answer 2

SQL stands for Structured Query Language and is used to communicate with a relational database. It’s the standard language for relational database management systems (RBMS).

Question 3

What SQL statements can be used to achieve almost everything you need to do with a database?

Answer 3

1. Select
2. Update
3. Insert
4. Delete
5. Create
6. Drop

Question 4

What are common dialects of SQL?

Answer 4

• Transact-SQL (T-SQL): Use by by Microsoft SQL server and Azure SQL services.
• pgSQL: Use by PostgreSQL.
• PL (procedural language)/SQL: Use by Oracle.

Question 5

What is Data Definition Language (DDL) and the common statements?

Answer 5

DDL statements are used to create, modify, and remove tables and other objects in a database (tables, stored procedures, views, etc.)
Common DDL statements:
* CREATE - create a new object in database
* ALTER - modify the structure of an object.
* DROP - remove an object from the database.
* RENANME - rename an exisiting object.

Example:
CREATE TABLE Product
(
ID INT PRIMARY KEY,
Name VARCHAR(20) NOT NULL,
Price DECIMAL NULL);

Question 6

What is Data Control Language (DCL) and the common statements?

Answer 6

DCL statements are used to manage access to objects in a database by granting, denying, or revoking permissions to specific users or groups.
Main DCL statements:
* GRANT - grant permissions to perform specific actions.
* DENY - deny permissions to perform specific actions.
* REVOKE - remove previously granted permission.

Example:
GRANT SELECT, INSERT, UPDATE
ON Product TO user1;

Question 7

What is Data Manipulation Language (DML) and the common statements?

Answer 7

DML statement are used to manipulate the rows in tables. They enable users to retrieve data, insert new rows, or modify existing rows.
Main statements:
* SELECT - read rows from a table
* INSERT - insert new rows into a table
* UPDATE - modify data in existing rows
* DELETE - delete exisiting rows

Example:
SELECT * FROM Customer WHERE City = “Seattle”: