mysql - mysql alter 命令可能导致数据丢失？

Question

虽然我不认为数据丢失是可能的，但我想仔细检查以下查询是否会导致数据丢失。我正在添加索引并增加 varchar 长度。

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

不管怎样，都应该对比一下手术前后的数据。

改变前做mysqldump --extended-insert=FALSE ... > old.sql，改变后做同样的> new.sql，然后diff -u old.sql new.sql |更少可以肯定。

extended-insert=FALSE 部分需要将每个表行放在单独的行上，以便于diff。