ماڈیول 2 · سبق 2 از 4کورس میں 6/57~6 min

ماڈیول اسباق (2/4)

DISTINCT کے ساتھ منفرد اقدار

Sometimes a column contains repeated values and you only care about the list of distinct values. The keyword DISTINCT placed right after SELECT removes duplicates from the result:

SQL

SELECT DISTINCT <colonne>
FROM   <tabella>
[WHERE <condizione>];

Uniqueness is evaluated over the combination of all listed columns. If you list two columns, two rows are considered equal only when both values match.

Examples

SQL

-- Le città in cui abbiamo almeno un dipartimento:
SELECT DISTINCT city FROM departments;

-- Le coppie (dipartimento, città) presenti (qui ognuna unica):
SELECT DISTINCT department_id, hired_on
FROM employees;

Try it

ورزش#sql.m2.l2.e1

کوششیں: 0لوڈ ہو رہا ہے…

List the distinct department_id values present among employees (duplicates must disappear).

ایڈیٹر لوڈ ہو رہا ہے…

اشارہ دکھائیں۔

Add DISTINCT right after SELECT to remove duplicates.

3 کوششوں کے بعد حل دستیاب ہے۔

Review exercise

ورزش#sql.m2.l2.e2