Define Data Definition Language (DDL) .

DDL is used to build and manage the structure of a relational database, by creating and modifying tables, fields, indexes and relationships.

Define Data Manipulation Language (DML) .

DML is used to manage the data stored within the database structures created by DDL, dealing with adding, updating, deleting and retrieving data.

What is the difference between DDL and DML?

DDL structures the database, whereas DML maintains the contents of the database.

What syntax do both DDL and DML use?

Both DDL and DML use SQL syntax to interact with the database.

True or False? A DBMS needs a different language for DDL and for DML.

False. Most modern DBMSs use SQL to support both DDL and DML operations.

DDL defines how data is by creating and modifying tables, fields, indexes and relationships.

DDL defines how data is stored by creating and modifying tables, fields, indexes and relationships.

What does CREATE DATABASE do?

CREATE DATABASE creates a new database .

What does CREATE TABLE do?

CREATE TABLE creates a new table with specified fields and data types.

What does ALTER TABLE do?

ALTER TABLE changes an existing table , for example to add or remove fields.

Name the seven data types available for attributes.

CHARACTER , VARCHAR(n) , BOOLEAN , INTEGER , REAL , DATE and TIME .

What is the difference between CHARACTER and VARCHAR(n) ?

CHARACTER stores fixed-length text , whereas VARCHAR(n) stores variable-length text up to a maximum length of n.

Which data type stores whole numbers, and which stores decimal numbers?

INTEGER stores whole numbers and REAL stores decimal numbers .

The data type stores a True or False value.

The data type BOOLEAN stores a True or False value.

What does PRIMARY KEY (field) do?

It sets a field as the primary key , the unique identifier for records in that table.

Which commands can a PRIMARY KEY clause be used inside?

It can be used inside a CREATE TABLE command or an ALTER TABLE command.

What does FOREIGN KEY (field) REFERENCES Table(Field) do?

It sets up a foreign key relationship between two tables .

What does SELECT ... FROM do?

SELECT ... FROM retrieves specific columns from a table.

WHERE filters the results based on a condition .

Write an SQL statement that lists all students older than 16 from a Students table.

SELECT * FROM Students WHERE Age > 16

What does ORDER BY do?

ORDER BY sorts the results into ascending or descending order.

What does GROUP BY do?

GROUP BY groups rows that have the same value in specified columns.

What does INNER JOIN do?

INNER JOIN combines rows from two tables where there is a matching key .

What is the difference between SUM() and COUNT() ?

SUM() calculates the total of a numeric column , whereas COUNT() counts the number of rows , or the non-null entries in a column.

AVG() calculates the average value of a numeric column .

What does INSERT INTO do?

INSERT INTO adds a new record to a table.

What does DELETE FROM do?

DELETE FROM removes records from a table.

UPDATE modifies existing data in a table.

True or False? UPDATE is a DDL command.

False. UPDATE is a DML command, because it changes the data in a table rather than the structure of the table.

A LevelComputer ScienceCambridge (CIE)Flashcards8. DatabasesData Definition Language (DDL) & Data Manipulation Language (DML)

Data Definition Language (DDL) & Data Manipulation Language (DML) (Cambridge (CIE) A Level Computer Science): Flashcards

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Define Data Definition Language (DDL).

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Cards in this collection (28)

Define Data Definition Language (DDL).
DDL is used to build and manage the structure of a relational database, by creating and modifying tables, fields, indexes and relationships.
Define Data Manipulation Language (DML).
DML is used to manage the data stored within the database structures created by DDL, dealing with adding, updating, deleting and retrieving data.
What is the difference between DDL and DML?
DDL structures the database, whereas DML maintains the contents of the database.
What syntax do both DDL and DML use?
Both DDL and DML use SQL syntax to interact with the database.
True or False?
A DBMS needs a different language for DDL and for DML.
False.
Most modern DBMSs use SQL to support both DDL and DML operations.
DDL defines how data is by creating and modifying tables, fields, indexes and relationships.
DDL defines how data is stored by creating and modifying tables, fields, indexes and relationships.
What does CREATE DATABASE do?
CREATE DATABASE creates a new database.
What does CREATE TABLE do?
CREATE TABLE creates a new table with specified fields and data types.
What does ALTER TABLE do?
ALTER TABLE changes an existing table, for example to add or remove fields.
Name the seven data types available for attributes.
CHARACTER, VARCHAR(n), BOOLEAN, INTEGER, REAL, DATE and TIME.
What is the difference between CHARACTER and VARCHAR(n)?
CHARACTER stores fixed-length text, whereas VARCHAR(n) stores variable-length text up to a maximum length of n.
Which data type stores whole numbers, and which stores decimal numbers?
INTEGER stores whole numbers and REAL stores decimal numbers.
The data type stores a True or False value.
The data type BOOLEAN stores a True or False value.
What does PRIMARY KEY (field) do?
It sets a field as the primary key, the unique identifier for records in that table.
Which commands can a PRIMARY KEY clause be used inside?
It can be used inside a CREATE TABLE command or an ALTER TABLE command.
What does FOREIGN KEY (field) REFERENCES Table(Field) do?
It sets up a foreign key relationship between two tables.
What does SELECT ... FROM do?
SELECT ... FROM retrieves specific columns from a table.
What does WHERE do?
WHERE filters the results based on a condition.
Write an SQL statement that lists all students older than 16 from a Students table.
SELECT * FROM Students WHERE Age > 16
What does ORDER BY do?
ORDER BY sorts the results into ascending or descending order.
What does GROUP BY do?
GROUP BY groups rows that have the same value in specified columns.
What does INNER JOIN do?
INNER JOIN combines rows from two tables where there is a matching key.
What is the difference between SUM() and COUNT()?
SUM() calculates the total of a numeric column, whereas COUNT() counts the number of rows, or the non-null entries in a column.
What does AVG() do?
AVG() calculates the average value of a numeric column.
What does INSERT INTO do?
INSERT INTO adds a new record to a table.
What does DELETE FROM do?
DELETE FROM removes records from a table.
What does UPDATE do?
UPDATE modifies existing data in a table.
True or False?
UPDATE is a DDL command.
False.
UPDATE is a DML command, because it changes the data in a table rather than the structure of the table.

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