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モジュール 2 · レッスン 3 / 4コース内の 7/57~6 min
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AS で名前を変更する

By default, columns in the result have the same name as the source column. When you select an expression (a calculation, a concatenation, an aggregate) the default name may look ugly or unclear. With AS you assign an alias, that is, a name of your choice:

SQL
SELECT <colonna_o_espressione> AS <alias>
FROM   <tabella>;

The keyword AS is optional (salary salary_eur works too), but writing it makes the query more readable. If the alias contains spaces or significant uppercase letters, wrap it in double quotes: AS "Annual Salary".

Examples

SQL
-- Rinomina semplice (in inglese per convenzione):
SELECT first_name AS name,
       last_name  AS surname
FROM employees;

-- Alias su un'espressione calcolata:
SELECT first_name,
       last_name,
       salary * 13 AS annual_pay
FROM employees;

Try it

運動#sql.m2.l3.e1
試行回数: 0読み込み中…

Extract each employee's last name and salary, renaming the columns to 'last' and 'salary_eur'.

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The keyword is AS: SELECT column AS new_name.

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Review exercise

運動#sql.m2.l3.e2
試行回数: 0読み込み中…

Extract first and last name concatenated into a single column called 'full_name'. Use the || operator to concatenate and put a space between the two.

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In PostgreSQL string concatenation is done with ||, and then the alias with AS.

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