mysql 怎么查表

SELECT column1, column2, ...
FROM table_name;

SELECT * FROM employees;

SELECT column1, column2, ...
FROM table_name
WHERE condition;

SELECT * FROM employees WHERE salary > 5000;

SELECT column1, column2, ...
FROM table_name
ORDER BY column_name ASC|DESC;

SELECT * FROM employees ORDER BY salary DESC;

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE condition
GROUP BY column_name;

SELECT department, AVG(salary) FROM employees GROUP BY department;

SELECT column_name(s)
FROM table1
JOIN table2 ON table1.column_name = table2.column_name;

SELECT employees.name, departments.department_name
FROM employees
JOIN departments ON employees.department_id = departments.department_id;

-- 查询所有数据
SELECT * FROM employees;

-- 查询工资大于 5000 的员工
SELECT * FROM employees WHERE salary > 5000;

-- 按工资降序排列
SELECT * FROM employees ORDER BY salary DESC;

-- 按部门分组并计算平均工资
SELECT department, AVG(salary) FROM employees GROUP BY department;

-- 连接 employees 和 departments 表
SELECT employees.name, departments.department_name
FROM employees
JOIN departments ON employees.department_id = departments.department_id;