My Addition

Question 1

In refernce of ALTER TABLE statements

What is the syntax for ADD

Answer 1

ALTER TABLE TableName 
ADD ColumnName DataType;

Question 2

In refernce of ALTER TABLE statements

What is the syntax for CHANGE

Answer 2

ALTER TABLE TableName 
CHANGE CurrentColumnName NewColumnName NewDataType;

Question 3

In refernce of ALTER TABLE statements

What is the syntax for DROP

Answer 3

ALTER TABLE TableName 
DROP ColumnName;

Question 4

What is the definition of tables in relational databases?

Answer 4

Tables are the core structure in relational databases containing a fixed sequence of columns and a varying set of rows.

Each column has a name and a specific data type, while each row consists of values that correspond to the column’s data types.

Question 5

What are the components of a table?

Answer 5

A table must have at least one column and can have multiple rows, but it can also be empty (having no rows).

Each column has a name and a specific data type.

Question 6

How do databases handle duplicate rows?

Answer 6

Some databases may allow duplicate rows temporarily, particularly when loading external data into a temporary table.

Question 7

What SQL statement is used to define a new table?

Answer 7

CREATE TABLE

This statement specifies table names and data types.

Question 8

What does the DROP TABLE statement do?

Answer 8

Deletes a table and all its data.

Question 9

What is the purpose of the ALTER TABLE statement?

Answer 9

Used to modify an existing table by adding, changing, or deleting columns.

Question 10

List common data types used in tables.

Answer 10

• integers (INT)
• values with 0 to N characters (VARCHAR(N))
• dates (DATE)
• decimals (DECIMAL)

Question 11

What rule governs the values in a cell of a table?

Answer 11

Exactly one value per cell.

Question 12

Are duplicate column names allowed in a table?

Answer 12

No duplicate column names are allowed within the same table but are allowed in different tables.

Question 13

What principle allows for optimization of storage in tables?

Answer 13

No significant row order, supporting the principle of data independence.

Question 14

What does it mean that there can be no duplicate rows in a table?

Answer 14

No two rows in a table may have identical values across all columns.

Question 15

What is a NULL value in a table?

Answer 15

Represents the absence of data in a cell.

Question 16

What is the SQL syntax for creating a table?

Answer 16

CREATE TABLE TableName (Column1 DATA_TYPE, Column2 DATA_TYPE, …, ColumnN DATA_TYPE);

Question 17

Fill in the blank: The ID column is of data type _______.

Answer 17

Integer (INT)

Question 18

What data type is used for the Name column?

Answer 18

Variable-length string with maximum 40 characters (VARCHAR(40)).

Question 19

What is the appropriate data type for the ProductType column?

Answer 19

Variable-length string with maximum 3 characters (VARCHAR(3)).

Question 20

What data type is used to store dates in a table?

Answer 20

Date.

Question 21

What is the format for the Weight column data type?

Answer 21

Decimal number with six significant digits and one digit after the decimal point (DECIMAL(6,1)).

Question 22

True or False: A table can have multiple rows with identical data.

Answer 22

False.

Question 23

Why are integers commonly used for IDs in databases?

Answer 23

They allow for efficient storage and quick retrieval when querying for specific products.

Question 24

What is the advantage of using VARCHAR for the Name column?

Answer 24

It allows for variable-length strings, using only the necessary space for each entry.

Question 25

Explain the data type DECIMAL(6,1).

Answer 25

It can accurately represent decimal numbers with up to 6 total digits, of which 1 digit is after the decimal point.