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SQL Basics
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Contenido del Curso

SQL Basics

SQL Basics

1. Selecting
The very first meet with the databaseSELECTing certain columnsLIMITing resultsUnique values from columnUnique values from multiple columnsHow many?How many unique?AliasesTables aliases
2. Filtering
Word filteringNumber filteringCombining conditionsFiltering by numeric intervalMultiple filtering on one columnLIKE filteringNOT like this!
3. Aggregating
MINimal and MAXimal valuesSUMming valuesMean valuesROUNDing
4. Sorting
Sorting by one columnSorting in DESCending orderThe cheapest carSorting by multiple columns
5. Grouping
What is grouping?More aggregate statistics!Grouping by multiple columnsThe cheapest combinationHAVING some conditionsLeast consuming carsFiltering group size
6. Practicing
Challenge: Unique combinationsChallenge: Average Q-series cars priceChallenge: The cheapest new A-series carsChallenge: Relation between engine size and fuel consumptionChallenge: Mileage and manufacture year - is there relation?Challenge: Average price for each model and yearChallenge: The most expensive transmission + engine size combinations

bookHow many?

What if you want to know the exact number of observations in your database? Counting manually sounds like a very very bad idea.

Fortunately, SQL has the built-in functionality of counting rows. To count the number of rows in the whole dataset use COUNT *. For example, we can count the total number of our website being visited by using the following query:


              
12

            
SELECT COUNT(*)
FROM visitors
copy

Please note, that for counting the total number of rows you must place * within parenthesis, like COUNT(*).

Tarea

Count number of Audi cars sold from audi_cars table.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Sección 1. Capítulo 6
toggle bottom row

bookHow many?

What if you want to know the exact number of observations in your database? Counting manually sounds like a very very bad idea.

Fortunately, SQL has the built-in functionality of counting rows. To count the number of rows in the whole dataset use COUNT *. For example, we can count the total number of our website being visited by using the following query:


              
12

            
SELECT COUNT(*)
FROM visitors
copy

Please note, that for counting the total number of rows you must place * within parenthesis, like COUNT(*).

Tarea

Count number of Audi cars sold from audi_cars table.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Sección 1. Capítulo 6
toggle bottom row

bookHow many?

What if you want to know the exact number of observations in your database? Counting manually sounds like a very very bad idea.

Fortunately, SQL has the built-in functionality of counting rows. To count the number of rows in the whole dataset use COUNT *. For example, we can count the total number of our website being visited by using the following query:


              
12

            
SELECT COUNT(*)
FROM visitors
copy

Please note, that for counting the total number of rows you must place * within parenthesis, like COUNT(*).

Tarea

Count number of Audi cars sold from audi_cars table.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

What if you want to know the exact number of observations in your database? Counting manually sounds like a very very bad idea.

Fortunately, SQL has the built-in functionality of counting rows. To count the number of rows in the whole dataset use COUNT *. For example, we can count the total number of our website being visited by using the following query:


              
12

            
SELECT COUNT(*)
FROM visitors
copy

Please note, that for counting the total number of rows you must place * within parenthesis, like COUNT(*).

Tarea

Count number of Audi cars sold from audi_cars table.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
Sección 1. Capítulo 6
Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
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