DELETE
功能描述
DELETE 语句用于从数据库表中删除符合指定条件的行。
注意事项
省略 WHERE 子句会删除表中所有行，请谨慎操作；建议在执行前先用 SELECT 确认待删除数据，并在事务中运行以便必要时回滚。
语法格式
sql
DELETE FROM [schema.]table_name [WHERE condition];参数说明
| 参数 | 说明 |
|---|---|
| DELETE FROM ... | 关键字，指示要执行删除操作。 |
| [schema.]table_name | 要删除数据的目标表的名称。 |
| [WHERE condition] | （可选）指定删除哪些行的条件。如果省略，将删除表中的所有行。 |
示例1: 删除所有符合条件的行
DELETE FROM employees WHERE id = 10;
DELETE FROM employees WHERE id IN (SELECT id FROM temp_employees WHERE processed = 'Y');示例2: 删除所有行 (谨慎使用)
DELETE FROM employees;示例
sql
-- 根据主键删除单行
DELETE FROM employees WHERE id = 100;
-- 根据范围条件删除
DELETE FROM employees WHERE salary < 30000;
-- 使用子查询删除
DELETE FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE location = 'Old Office');