Introduction to SQL

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Questions and Answers

Which SQL command is used to remove an entire database table?

ALIAS

UPDATE

INSERT

DROP (correct)

Which data type can store values ranging from -2147483648 to 2147483647?

CHAR

INT (correct)

FLOAT

VARCHAR

Which command would you use to make permanent changes to the database?

COMMIT (correct)

REVOKE

ROLLBACK

TRUNCATE

What is required for a user to create tables in an RDBMS?

Authentication Signup and view all the answers

Which command is intended to alter the structure of an existing table?

ALTER Signup and view all the answers

What is the purpose of the TRUNCATE command in SQL?

To delete all data in a table without removing the table itself Signup and view all the answers

Which of the following SQL commands is categorized under Data Control Language (DCL)?

GRANT Signup and view all the answers

When creating a database structure, which of the following statements is true?

Physical files created depend on the specific RDBMS. Signup and view all the answers

What effect does a constraint violation have on a data action?

The action is aborted Signup and view all the answers

What SQL command is used to change the name of an existing table?

ALTER TABLE Signup and view all the answers

Which statement correctly describes the CREATE TABLE syntax?

CREATE TABLE table_name (column1 datatype other_constraints, column2 datatype other_constraints); Signup and view all the answers

What command is used to view the structure of an already created table?

DESCRIBE table_name; Signup and view all the answers

Which SQL statement permanently removes both the data and structure of a table?

DROP TABLE table_name Signup and view all the answers

What is the primary difference between the TRUNCATE and DROP TABLE statements?

TRUNCATE removes all data without removing the table structure. Signup and view all the answers

What SQL statement is utilized to change the structure of a table?

ALTER Signup and view all the answers

Which command is NOT part of the ALTER statement operational commands?

DROPPED Signup and view all the answers

Which of the following statements correctly renames a table 'students' to 'ccestudents'?

ALTER TABLE students RENAME TO ccestudents Signup and view all the answers

What effect does the TRUNCATE statement have on a table?

Removes all rows but retains the table structure. Signup and view all the answers

Which data type is likely appropriate for storing a student's age?

INTEGER Signup and view all the answers

If you want to remove an existing column from a table, which command would you use in conjunction with ALTER?

DROP Signup and view all the answers

What is an essential feature of constraints in a table?

They ensure data complies with specified rules. Signup and view all the answers

What is the correct command to create a new database?

CREATE DATABASE database_name; Signup and view all the answers

Which command is used to display the databases that have been created?

SHOW DATABASES; Signup and view all the answers

What must be done before working with a particular database?

USE database_name; Signup and view all the answers

What is the consequence of using the DROP DATABASE command?

The database is permanently deleted along with its data. Signup and view all the answers

Which of the following is NOT a requirement for creating a table in MySQL?

Database size specification Signup and view all the answers

What specification can be used to ensure a field in a MySQL table cannot be null?

NOT NULL Signup and view all the answers

SQL constraints are used to achieve what purpose?

Specify rules for the data in a table Signup and view all the answers

Which SQL command is used to ensure the uniqueness of data in a particular field of a table?

UNIQUE Signup and view all the answers

What is the primary purpose of Structured Query Language (SQL)?

To manage data as collections of tables in relational databases Signup and view all the answers

Which command is used in SQL for data manipulation?

SELECT Signup and view all the answers

When was the first relational DB marketed with SQL?

1979 Signup and view all the answers

What does the SQL standard provide for database definitions?

Syntax and semantics for data definition and manipulation Signup and view all the answers

What does RDBMS stand for?

Relational Database Management System Signup and view all the answers

In which year was the ANSI SQL standard first released?

1986 Signup and view all the answers

How has the SQL standard evolved since its inception?

It has undergone multiple updates to enhance functionality Signup and view all the answers

Which of the following capabilities is enabled by the SQL standard?

Portability of database definitions and application modules Signup and view all the answers

Study Notes

Learning Objectives

Understand the definition of SQL.
Familiarity with basic commands and functions of SQL.
Learn data administration tasks such as creating tables and indexes.
Master data manipulation tasks including adding, modifying, deleting, and retrieving data.
Learn how to query a database for valuable information.

SQL Overview

SQL stands for Structured Query Language.
It serves as the standard for relational database management systems (RDBMS).
RDBMS organizes data into tables, using common values to represent relationships.

History of SQL

Developed in the 1970s by Edgar F. Codd, establishing the relational database concept.
System R, which incorporated SQL, was created at IBM Research by Donald D. Chamberlin and Raymond F. Boyce.
Oracle released the first commercial relational database with SQL in 1979.
Subsequent RDBMS released include SQL/DS (1981), INGRES (1981), and Sybase (1986).
ANSI established the SQL standard in 1986, with updates in 1989, 1992, 1999, 2003, 2006, 2008, 2011, and 2016.
SQL is widely supported by major database vendors today.

Purpose of SQL Standard

Specifies syntax and semantics for data definition and manipulation.
Defines data structures and basic operational guidelines.
Ensures portability of database definitions and application modules.
Establishes minimal (level 1) and complete (level 2) standards for SQL usage.
Facilitates future enhancements including referential integrity and transaction management.

Common SQL Commands

DDL (Data Definition Language): CREATE, DROP, ALTER, RENAME, TRUNCATE
DML (Data Manipulation Language): SELECT, INSERT, UPDATE, DELETE
DCL (Data Control Language): GRANT, REVOKE
TCL (Transaction Control Language): COMMIT, ROLLBACK

Tasks Before Using a New RDBMS

Create a database structure, which varies between RDBMS types.
Authentication is crucial to verify registered user access through user ID and password.

SQL Data Types

INT: Normal-sized integer, capable of signed (-2147483648 to 2147483647) or unsigned (0 to 4294967295) values.

Creating a Database

Command: CREATE DATABASE database_name;
Example: CREATE DATABASE mydb;

Displaying Databases

Use SHOW DATABASES; to view existing databases.

Selecting a Database

To work with a database, it must be selected using:
- Command: USE database_name;
- Example: USE mydb;

Deleting a Database

Command to remove a database:
- Command: DROP DATABASE database_name;
- Example: DROP DATABASE mydb;

Creating Table Structures

Command: CREATE TABLE table_name (column1 datatype other_constraints, ... );
Requires:
- Name of the table.
- Names of fields.
- Definitions for each field.

SQL Constraints

Constraints limit data types in tables to ensure accuracy and reliability.
Violations result in an aborted data action.

Changing Table Structure

Use the ALTER statement for renaming, adding, or deleting columns.
Renaming Example: ALTER TABLE students RENAME TO ccestudents;

Deleting an Entire Table Structure

Command: DROP TABLE table_name;
Example: DROP TABLE students;

Emptying a Table

Use TRUNCATE TABLE table_name; to remove all data without deleting table structure.
Example: TRUNCATE TABLE students;

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Description

This quiz covers the fundamentals of Structured Query Language (SQL), including its basic commands and functions. You'll learn how to create tables, manage indexes, and manipulate data effectively using SQL. Test your knowledge on the essential components of SQL in this introductory quiz.