MySQL字段长度与索引限制问题的原因分析及解决方案

2025-07-08 15:40:48 [scheduling-1] ERROR o.s.s.s.TaskUtils$LoggingErrorHandler - Unexpected error occurred in scheduled task
org.springframework.dao.DataIntegrityViolationException: 
### Error updating database.  Cause: com.mysql.cj.jdbc.exceptions.MysqlDataTruncation: Data truncation: Data too long for column 'card_number' at row 1

163326141751950071490603524,163326141751950071490263532,...

ALTER TABLE loc_order_info MODIFY COLUMN card_number VARCHAR(1000);

-- 原表
CREATE TABLE loc_order_info (
    id BIGINT PRIMARY KEY,
    order_id VARCHAR(50),
    -- 其他字段...
);

-- 卡号关联表
CREATE TABLE loc_order_card_numbers (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    order_id BIGINT,
    card_number VARCHAR(50),
    FOREIGN KEY (order_id) REFERENCES loc_order_info(id)
);

if (cardNumber.length() > maxLength) {
    cardNumber = cardNumber.substring(0, maxLength);
}

Specified key was too long; max key length is 3072 bytes

-- 查看索引
SHOW INDEX FROM loc_order_info;

-- 移除索引（如非必要）
ALTER TABLE loc_order_info DROP INDEX idx_card_number;

-- 再修改字段
ALTER TABLE loc_order_info MODIFY COLUMN card_number VARCHAR(1000);

ALTER TABLE loc_order_info MODIFY COLUMN card_number VARCHAR(1000);
ALTER TABLE loc_order_info ADD INDEX idx_card_prefix (card_number(191)); -- 前191字符

ALTER TABLE loc_order_info MODIFY COLUMN card_number VARCHAR(1000) CHARACTER SET utf8;

SELECT 
    *,
    LENGTH(card_number) AS card_length
FROM loc_card_info 
WHERE card_number LIKE '%,%'
ORDER BY card_length DESC;

SELECT * 
FROM loc_card_info 
ORDER BY LENGTH(card_number) DESC
LIMIT 10;

SELECT 
    LENGTH(card_number) AS length,
    COUNT(*) AS count
FROM loc_card_info
GROUP BY length
ORDER BY length DESC;