从备份创建新的MySql模式。SQL源文件会重置自动增量ID列吗？

Question

I am developing a large database schema that I desire to make available to clients.

I am new to MySql database administration. How do I restore a .sql file of the schema so that it also resets ALL auto incremental id columns back to 0 or Null again.

I actually restored to a new schema name and inserted a test record and found the auto id columns were incrementing from where they left-off in the last schema name.

How do I address this in MySql database modeling?

I want to always be able to 'spin-off' an exact copy of my current version data model for a paying customer.

Thank you.

Answer 1

You can dump the schema only, without data this way:

$ mysqldump -d databasename > databasename-schema.sql

If you use InnoDB tables (which you should), the auto-increment value is always reset every time you restart the MySQL instance. The value it is reset to in each table is equal to the max value currently stored in the table, plus 1. So if your tables are empty, the value will be 1.

If you don't want to restart the MySQL instance after you restore, you can either strip the auto-increment clause in your CREATE TABLE statements before restoring:

$ mysqldump -d databasename | sed -e 's/AUTO_INCREMENT=[0-9][0-9]*//' 
  > databasename-schema.sql

Or else you can ALTER TABLE to reset the auto-increment value after restoring. This has to be done on a per-table basis, but you can query the list of tables that have auto-increment keys from the INFORMATION_SCHEMA:

$ mysql -N -B -e "SELECT CONCAT('ALTER TABLE \`', table_schema, '\`.\`', 
  table_name, '\` AUTO_INCREMENT=1;') AS ddl FROM INFORMATION_SCHEMA.TABLES 
  WHERE table_schema = 'test' AND AUTO_INCREMENT IS NOT NULL" | mysql -v

Answer 2

您可以使用它来转储表结构，并且您将像之前定义的那样从头开始找到所有自动增量主键，它将不执行插入查询，并且将创建所有stored procedure ， views和tables ：

cat backup.sql | grep -v ^INSERT | mysql -u $USER -p

Answer 3

AUTO_INCREMENT is reset after

TRUNCATE `table`

and when you run batch INSERT query afterwards (from your data backup), the AUTO_INCREMENT value will be automaticaly updated to proper value (inserted records+1).

So you don't need to update AUTO_INCREMENT value manualy (which is rather a bad practice).

When you want to restore from backup more that one table that are constrained by foreign keys, you can disable FK checks before TRUNCATE+INSERT and enable it back when you're done. Details can be found here: Truncate all tables (most of which have constraints). How to temporarily drop them