Contenido del Curso

SQL Basics

1. Selecting

The very first meet with the database SELECTing certain columns LIMITing results Unique values from column Unique values from multiple columns How many?How many unique?Aliases Tables aliases

2. Filtering

Word filtering Number filtering Combining conditions Filtering by numeric interval Multiple filtering on one column LIKE filtering NOT like this!

3. Aggregating

MINimal and MAXimal values SUMming values Mean values ROUNDing

4. Sorting

Sorting by one column Sorting in DESCending order The cheapest car Sorting by multiple columns

5. Grouping

What is grouping?More aggregate statistics!Grouping by multiple columns The cheapest combination HAVING some conditions Least consuming cars Filtering group size

6. Practicing

Challenge: Unique combinations Challenge: Average Q-series cars price Challenge: The cheapest new A-series cars Challenge: Relation between engine size and fuel consumption Challenge: Mileage and manufacture year - is there relation?Challenge: Average price for each model and year Challenge: The most expensive transmission + engine size combinations

Multiple filtering on one column

What if we are interested only in two models: let it be A4 and A5?

Of course, we could write WHERE model = 'A4' OR model = 'A5'. But is there a point in writing two conditions for the same column? This problem is also solved in SQL by using IN statement. To check if a value from a column is one of acceptable use WHERE column IN ('value1', 'value2', ...) syntax. For example,


              123
            
SELECT *
FROM audi_cars
WHERE model IN ('A4', 'A5')

WHERE column IN ('value1', 'value2') is equvivalent to WHERE column = 'value1' OR column = 'value2'. It also works for numeric values.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones

¿Todo estuvo claro?

Sección 2. Capítulo 5

Multiple filtering on one column

What if we are interested only in two models: let it be A4 and A5?


              123
            
SELECT *
FROM audi_cars
WHERE model IN ('A4', 'A5')

WHERE column IN ('value1', 'value2') is equvivalent to WHERE column = 'value1' OR column = 'value2'. It also works for numeric values.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones

¿Todo estuvo claro?

Sección 2. Capítulo 5

Multiple filtering on one column

What if we are interested only in two models: let it be A4 and A5?


              123
            
SELECT *
FROM audi_cars
WHERE model IN ('A4', 'A5')

WHERE column IN ('value1', 'value2') is equvivalent to WHERE column = 'value1' OR column = 'value2'. It also works for numeric values.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones

¿Todo estuvo claro?

What if we are interested only in two models: let it be A4 and A5?


              123
            
SELECT *
FROM audi_cars
WHERE model IN ('A4', 'A5')

WHERE column IN ('value1', 'value2') is equvivalent to WHERE column = 'value1' OR column = 'value2'. It also works for numeric values.

Tarea

From audi_cars extract cars with engine size (enginesize column) 1.5 and 2.9 using IN statement.

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones

Sección 2. Capítulo 5

Cambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones