Зміст курсу

SQL Tutorial for Beginners

1. Database & Introduction to Syntax

Meet the SQL Select the Songs!SQL Select Column SQL Distinct SQL Where Challenge Where SQL And, Or, Not

2. SQL Aggregate Functions

SQL Min and Max Challenge Min and Max SQL Count, Sum, Avg Challenge Count

3. Filtering Statements

SQL Null SQL Like Challenge Like SQL Between SQL Order By Challenge Order By SQL Group By Challenge Group By SQL Top and Limit SQL Aliases SQL Having Challenge Having SQL Comments

SQL Where

You’ll need to filter your selected data very often, so you need to use WHERE keyword. After WHERE you put some condition or combination of them. Usually it is some column's values limitations.

For example, you want to select records where singer is AC/DC:


              12
            
SELECT * FROM songs
WHERE singer = 'AC/DC'

Another example of the query using the WHERE statement. It retrieves all records with a price column value greater than 100. The syntax is pretty easy to understand: WHERE price > 100.


              12
            
SELECT * FROM songs
WHERE price > 100

Here you can see the main syntax.

Use = to find fields which values are equal to some naming.
Use != or <> to find non-equal fields.
Use >, <, >=, <= for comparing.
Use single quotes 'Quotes' for string values.
Use () brackets for prioritization.


              123
            
/* all records where year column is greater or equal than 1970*/
SELECT * FROM songs
WHERE year >= 1970

For string values, you have to write them inside single quotes. Like 'ABBA', 'Toxic' etc. Check carefully string values in the condition statements: no extra spaces, correct capitalization (for example, Britney Spears is correct, not BRITNEY SPEARS or britney spears). Otherwise, you'll receive the Internal Server Error.

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів

Все було зрозуміло?

Секція 1. Розділ 5

SQL Where

For example, you want to select records where singer is AC/DC:


              12
            
SELECT * FROM songs
WHERE singer = 'AC/DC'

Another example of the query using the WHERE statement. It retrieves all records with a price column value greater than 100. The syntax is pretty easy to understand: WHERE price > 100.


              12
            
SELECT * FROM songs
WHERE price > 100

Here you can see the main syntax.

Use = to find fields which values are equal to some naming.
Use != or <> to find non-equal fields.
Use >, <, >=, <= for comparing.
Use single quotes 'Quotes' for string values.
Use () brackets for prioritization.


              123
            
/* all records where year column is greater or equal than 1970*/
SELECT * FROM songs
WHERE year >= 1970

For string values, you have to write them inside single quotes. Like 'ABBA', 'Toxic' etc. Check carefully string values in the condition statements: no extra spaces, correct capitalization (for example, Britney Spears is correct, not BRITNEY SPEARS or britney spears). Otherwise, you'll receive the Internal Server Error.

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Все було зрозуміло?

Секція 1. Розділ 5

SQL Where

For example, you want to select records where singer is AC/DC:


              12
            
SELECT * FROM songs
WHERE singer = 'AC/DC'

Another example of the query using the WHERE statement. It retrieves all records with a price column value greater than 100. The syntax is pretty easy to understand: WHERE price > 100.


              12
            
SELECT * FROM songs
WHERE price > 100

Here you can see the main syntax.

Use = to find fields which values are equal to some naming.
Use != or <> to find non-equal fields.
Use >, <, >=, <= for comparing.
Use single quotes 'Quotes' for string values.
Use () brackets for prioritization.


              123
            
/* all records where year column is greater or equal than 1970*/
SELECT * FROM songs
WHERE year >= 1970

For string values, you have to write them inside single quotes. Like 'ABBA', 'Toxic' etc. Check carefully string values in the condition statements: no extra spaces, correct capitalization (for example, Britney Spears is correct, not BRITNEY SPEARS or britney spears). Otherwise, you'll receive the Internal Server Error.

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Все було зрозуміло?

For example, you want to select records where singer is AC/DC:


              12
            
SELECT * FROM songs
WHERE singer = 'AC/DC'

Another example of the query using the WHERE statement. It retrieves all records with a price column value greater than 100. The syntax is pretty easy to understand: WHERE price > 100.


              12
            
SELECT * FROM songs
WHERE price > 100

Here you can see the main syntax.

Use = to find fields which values are equal to some naming.
Use != or <> to find non-equal fields.
Use >, <, >=, <= for comparing.
Use single quotes 'Quotes' for string values.
Use () brackets for prioritization.


              123
            
/* all records where year column is greater or equal than 1970*/
SELECT * FROM songs
WHERE year >= 1970

For string values, you have to write them inside single quotes. Like 'ABBA', 'Toxic' etc. Check carefully string values in the condition statements: no extra spaces, correct capitalization (for example, Britney Spears is correct, not BRITNEY SPEARS or britney spears). Otherwise, you'll receive the Internal Server Error.

Завдання

Select all records with Britney Spears as a singer. Change your query to select only Britney Spears songs' titles (not full records, only column title).

Секція 1. Розділ 5