MySQL对字段新增自增序列

　　现在有这样的场景，我们的数据库类型是MySQL，表是从其他库拿过来的，约束和索引都没迁移。现在希望增加一个自增序列。

且自增序列是从当前最大自增ID开始的，下面就是这样一个过程的演示。

mysql> create table t_test1(id int,name varchar(1000));
Query OK, 0 rows affected (0.12 sec)

# 修改id字段为主键字段，且自增

mysql> alter table t_test1 modify id int primary key auto_increment ;
Query OK, 0 rows affected (0.06 sec)
Records: 0  Duplicates: 0  Warnings: 0

# 插入数据，自动填充id

mysql> insert into t_test1(name) values('xiaoming');
Query OK, 1 row affected (0.00 sec)

mysql> select * from t_test1;
+----+----------+
| id | name     |
+----+----------+
|  1 | xiaoming |
+----+----------+
1 row in set (0.00 sec)

# 修改t_test1 表的自增起始值

mysql> alter table t_test1 auto_increment = 1000;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> insert into t_test1(name) values('xiaoming');
Query OK, 1 row affected (0.01 sec)

# 自增序列从起始值开始

mysql> select * from t_test1;
+------+----------+
| id   | name     |
+------+----------+
|    1 | xiaoming |
| 1000 | xiaoming |
+------+----------+
2 rows in set (0.00 sec)