Cách lấy dữ liệu từ bảng cơ sở dữ liệu SQL
Bạn có thể lấy dữ liệu ra khỏi bảng bằng cách sử dụngSELECTchỉ huy.
Nhận tất cả các hàng và cột:
SELECT * FROM people; age | name
-----+--------
37 | Flavio
8 | RogerGet only the name column:
SELECT name FROM people;
name
--------
Flavio
RogerCount the items in the table:
SELECT COUNT(*) from people;
count
-------
2You can filter rows in a table adding the WHERE clause:
SELECT age FROM people WHERE name='Flavio';
age
-----
37The results of a query can be ordered by column value, ascending (the default) or descending, using ORDER BY:
SELECT * FROM people ORDER BY name;
SELECT * FROM people ORDER BY name DESC;
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