Implementation of MySQL Field Auto-Increment

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:

 
 

  
  
create table tableName (id unsigned int primary key auto_increment not null,  
  
  
 title varchar(32),  
  
  
 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

 
 

  
  
ALTER TABLE tablename DROP id;  
  
  
ALTER TABLE tablename ADD id INT NOT NULL PRIMARY KEY AUTO_INCREMENT FIRST  
 
 

If the auto-increment ID (int) of mysql is insufficient, use bigInt instead.
Mysql:
INT [(M)] [UNSIGNED] [ZEROFILL]
A normal integer. The signed range is-2147483648 to 2147483647, And the unsigned range is 0 to 4294967295.
BIGINT [(M)] [UNSIGNED] [ZEROFILL]
A large integer. The signed range is-9223372036854775808 to 9223372036854775807, And the unsigned range is 0

18446744073709551615

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

Implement ID auto-Increment

 
 

  
  
public int maxid() throws SQLException  
  
  
{  
  
  
 stmt = conn.createStatement();  
  
  
 rs = stmt.executeQuery("select max(id) from tableName");  
  
  
 int maxid = 1;  
  
  
 while(rs.next())  
  
  
 {  
  
  
  maxid = rs.getInt(1) + 1;  
  
  
 }  
  
  
   
  
  
 return maxid;  
  
  
}   
  
  
 
 
 

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