1. 创建表（CREATE TABLE）:
CREATE TABLE students (
student_id SERIAL PRIMARY KEY,
first_name VARCHAR(50),
last_name VARCHAR(50),
age INT
);
2. 插入数据（INSERT INTO）:
INSERT INTO students (first_name, last_name, age) VALUES
('John', 'Doe', 25),
('Jane', 'Smith', 22),
('Bob', 'Johnson', 28);
3. 查询数据（SELECT）:
SELECT * FROM students;
4. 更新数据（UPDATE）:
UPDATE students SET age = 26 WHERE first_name = 'John';
5. 删除数据（DELETE）:
DELETE FROM students WHERE last_name = 'Smith';
6. 筛选数据（WHERE子句）:
SELECT * FROM students WHERE age > 25;
7. 排序数据（ORDER BY）:
SELECT * FROM students ORDER BY last_name ASC;
8. 聚合函数（SUM、AVG、COUNT等）:
SELECT AVG(age) FROM students;
9. 连接表（JOIN）:
SELECT students.first_name, students.last_name, courses.course_name
FROM students
INNER JOIN courses ON students.student_id = courses.student_id;
以上只是一些基础的SQL语法示例。实际上，SQL语法非常丰富，可以执行各种复杂的查询和操作。
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