Implementation of MySQL Field Auto-Increment

Source: Internet
Author: User

We often use MySQL Field Auto-growth. The following describes the implementation process of MySQL Field Auto-growth in detail. If you are interested in this aspect, take a look.

MySQL field self-growth:

  1. create table tableName (id unsigned int primary key auto_increment not null,  
  2.  title varchar(32),  
  3.  content text);  

Auto_increment is an auto-increment attribute.

How does mysql specify the id and then auto-Increment
Auto_increment = 100;

Enables MySQL to automatically increase field numbers from continuous to continuous

  1. ALTER TABLE tablename DROP id;  

If the auto-increment ID (int) of mysql is insufficient, use bigInt instead.
A normal integer. The signed range is-2147483648 to 2147483647, And the unsigned range is 0 to 4294967295.
A large integer. The signed range is-9223372036854775808 to 9223372036854775807, And the unsigned range is 0


Obtain the largest ID from MySQL, select max (id) from tableName;

Implement ID auto-Increment

  1. public int maxid() throws SQLException  
  2. {  
  3.  stmt = conn.createStatement();  
  4.  rs = stmt.executeQuery("select max(id) from tableName");  
  5.  int maxid = 1;  
  6.  while(  
  7.  {  
  8.   maxid = rs.getInt(1) + 1;  
  9.  }  
  11.  return maxid;  
  12. }   

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