mysql 提示已经存在

-- 检查是否存在相同的数据
SELECT * FROM table_name WHERE column_name = 'value';

-- 插入数据时避免重复
INSERT INTO table_name (column1, column2)
SELECT 'value1', 'value2'
FROM DUAL
WHERE NOT EXISTS (
    SELECT 1 FROM table_name WHERE column_name = 'value'
);

-- 更新现有数据
UPDATE table_name SET column1 = 'new_value' WHERE column_name = 'value';

-- 删除重复数据
DELETE FROM table_name
WHERE column_name IN (
    SELECT column_name
    FROM (
        SELECT column_name, ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY id) AS row_num
        FROM table_name
    ) t
    WHERE row_num > 1
);