Usando Subconsultas Internas na Seção FROM

An inner subquery creates a table with which we then perform operations in the outer query.

From this, we can conclude that we can also use an inner query within the FROM section to select something from this table.

Let's consider an example where we need to work with employees whose salary is above a certain value. But instead of a WHERE clause, we will use an inner query:


              123456
            
SELECT *
FROM (
  SELECT * 
  From employees
  WHERE salary >= 70000
) AS high_salary_employees

We've created a new table using an inner subquery with which we can work and gather information.

Note

Notice that for such a table, it's essential to provide an alias.

When might this be useful?

Such a query is highly readable; sometimes, it can replace a WHERE clause.

Additionally, if you need to work not with the entire table but only with a filtered part, an inner subquery within the FROM section can be extremely handy.

Tarefa

Swipe to begin your solution

Your task is to retrieve the average budget (budget column) for all managerial departments from the department table. Use an inner subquery in the FROM section to filter only the managerial type of department. Also, use the alias manager_departments for this table so the task is checked correctly.

Note:

The response should have only one column, average_budget. This is an alias for the aggregate function AVG().

Solução

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Seção 2. Capítulo 3

Usando Subconsultas Internas na Seção FROM

An inner subquery creates a table with which we then perform operations in the outer query.

From this, we can conclude that we can also use an inner query within the FROM section to select something from this table.

Let's consider an example where we need to work with employees whose salary is above a certain value. But instead of a WHERE clause, we will use an inner query:


              123456
            
SELECT *
FROM (
  SELECT * 
  From employees
  WHERE salary >= 70000
) AS high_salary_employees

We've created a new table using an inner subquery with which we can work and gather information.

Note

Notice that for such a table, it's essential to provide an alias.

When might this be useful?

Such a query is highly readable; sometimes, it can replace a WHERE clause.

Additionally, if you need to work not with the entire table but only with a filtered part, an inner subquery within the FROM section can be extremely handy.

Tarefa

Swipe to begin your solution

Note:

The response should have only one column, average_budget. This is an alias for the aggregate function AVG().

Solução

Mude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo

Tudo estava claro?

Obrigado pelo seu feedback!

Seção 2. Capítulo 3

Mude para o desktop para praticar no mundo realContinue de onde você está usando uma das opções abaixo