SQLPlus 是 Oracle 数据库的一个命令行工具，用于执行 SQL 查询、PL/SQL 程序等。在 SQLPlus 中编写查询语句的基本格式如下：
SELECT column1, column2, ...
FROM table_name
WHERE condition;
以下是一些具体的示例：
SELECT *
FROM employees;
SELECT first_name, last_name, email
FROM employees;
SELECT first_name, last_name, email
FROM employees
WHERE department_id = 10;
SELECT COUNT(*)
FROM employees;
SELECT SUM(salary)
FROM employees;
SELECT AVG(salary)
FROM employees;
SELECT e.first_name, e.last_name, d.department_name
FROM employees e
JOIN departments d ON e.department_id = d.department_id;
SELECT department_id, COUNT(*)
FROM employees
GROUP BY department_id;
SELECT first_name, last_name, salary
FROM employees
ORDER BY salary DESC;
这些示例仅涵盖了 SQLPlus 查询语句的基本用法。实际上，SQLPlus 支持许多高级功能，如子查询、公共表表达式（CTE）、窗口函数等。您可以根据需要编写更复杂的查询语句。
