Column definitions and constraints in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a column named 'age' as an integer.

MySQL

CREATE TABLE Persons (age [1]);

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AINT

BTEXT

CVARCHAR(100)

DDATE

Attempts:

3 left

💡 Hint

Common Mistakes

Using VARCHAR for numeric data.

Using DATE for age.

The INT data type is used to define integer columns in MySQL.

2fill in blank

medium

Complete the code to add a NOT NULL constraint to the 'name' column.

MySQL

CREATE TABLE Employees (name VARCHAR(50) [1]);

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ANOT NULL

BDEFAULT NULL

CUNIQUE

DPRIMARY KEY

Attempts:

3 left

💡 Hint

Common Mistakes

Using DEFAULT NULL instead of NOT NULL.

Confusing UNIQUE with NOT NULL.

The NOT NULL constraint ensures the column cannot have NULL values.

3fill in blank

hard

Fix the error in the code to set 'id' as the primary key.

MySQL

CREATE TABLE Orders (id INT [1], order_date DATE);

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AUNIQUE

BPRIMARY KEY

CNOT NULL

DFOREIGN KEY

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNIQUE instead of PRIMARY KEY.

Forgetting to add NOT NULL with PRIMARY KEY.

The PRIMARY KEY constraint uniquely identifies each record in the table.

4fill in blank

hard

Fill all three blanks to define a 'salary' column as decimal with 10 digits total and 2 decimal places, and ensure it cannot be NULL.

MySQL

CREATE TABLE Staff (salary [1]([2], 2) [3]);

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ADECIMAL

B10

CNOT NULL

DVARCHAR

Attempts:

3 left

💡 Hint

Common Mistakes

Using VARCHAR for salary.

Omitting NOT NULL constraint.

DECIMAL(10, 2) defines a number with 10 digits total and 2 after the decimal point. NOT NULL ensures the column must have a value.

5fill in blank

hard

Fill all three blanks to define a 'username' column as VARCHAR(30), make it UNIQUE, and set a default value 'guest'.

MySQL

CREATE TABLE Users (username [1]([2]) DEFAULT 'guest' [3]);

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AVARCHAR

B30

CUNIQUE

DINT

Attempts:

3 left

💡 Hint

Common Mistakes

Using INT for username.

Forgetting UNIQUE constraint.

VARCHAR(30) defines a text column with max 30 characters. UNIQUE ensures no two users have the same username. DEFAULT 'guest' sets the default username if none is provided.