要在SQL中删除行,您需要使用DELETE
语句。以下是详细的用法说明:
DELETE FROM 表名
WHERE 条件;
删除特定条件的行:
DELETE FROM customers
WHERE customer_id = 123;
删除所有行(清空表):
DELETE FROM orders;
注意:这会删除表中所有数据,但保留表结构
使用复杂条件删除:
DELETE FROM products
WHERE price < 10 AND stock_quantity = 0;
WHERE子句的重要性:
sql
SELECT * FROM customers WHERE customer_id = 123;
事务控制:
sql
BEGIN TRANSACTION;
DELETE FROM employees WHERE department = 'HR';
-- 检查影响的行数
COMMIT; -- 或 ROLLBACK; 如果需要撤销
替代方案:
sql
TRUNCATE TABLE log_entries;
MySQL:支持LIMIT子句限制删除行数
DELETE FROM large_table LIMIT 1000;
SQL Server:可以使用TOP子句
DELETE TOP(100) FROM audit_log;
Oracle:使用ROWNUM限制
DELETE FROM temp_data WHERE ROWNUM <= 100;
在执行删除操作前,强烈建议先备份数据或确认WHERE条件准确无误。