使用mysql alter命令可能導致數據丟失？

Question

雖然我不認爲數據丟失是可能的，但我想仔細檢查下列查詢是否會導致數據丟失。我正在添加索引並增加varchar長度。

ALTER TABLE `phppos_sales` ADD `deleted` INT(1) NOT NULL DEFAULT '0'; 
ALTER TABLE `phppos_items` ADD INDEX ( `name`); 
ALTER TABLE `phppos_items` ADD INDEX ( `category`); 
ALTER TABLE `phppos_items` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_customers` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_employees` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_giftcards` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_item_kits` ADD INDEX ( `name`); 
ALTER TABLE `phppos_people` ADD INDEX ( `first_name`); 
ALTER TABLE `phppos_people` ADD INDEX ( `last_name`); 
ALTER TABLE `phppos_people` ADD INDEX ( `email`); 
ALTER TABLE `phppos_sales` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_suppliers` ADD INDEX ( `deleted`); 
ALTER TABLE `phppos_receivings` CHANGE `payment_type` `payment_type` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_receivings_items` CHANGE `description` `description` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_receivings_items` CHANGE `serialnumber` `serialnumber` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales` CHANGE `payment_type` `payment_type` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales_suspended` CHANGE `payment_type` `payment_type` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_giftcards` CHANGE `giftcard_number` `giftcard_number` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL; 
ALTER TABLE `phppos_sales_items` CHANGE `description` `description` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales_items` CHANGE `serialnumber` `serialnumber` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales_suspended_items` CHANGE `description` `description` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales_suspended_items` CHANGE `serialnumber` `serialnumber` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NULL DEFAULT NULL; 
ALTER TABLE `phppos_sales_suspended_payments` CHANGE `payment_type` `payment_type` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL; 
ALTER TABLE `phppos_sales_payments` CHANGE `payment_type` `payment_type` VARCHAR(255) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL; 

Answer 1

無論如何，您應該比較操作前後的數據。

做mysqldump --extended-insert=FALSE ... > old.sql改變之前，和> new.sql改變之後，然後diff -u old.sql new.sql | less可以肯定。

需要使用extended-insert=FALSE零件將每個表格行放在單獨的行上，以便更容易地使用diff。