mysql Realize self increasing sequence

Mysql Implementation sequence

Create a table dedicated to sequences ：

create table sequence (         
seq_name        VARCHAR(50) NOT NULL, --  Sequence name          
current_val     INT         NOT NULL, --  Current value          
increment_val   INT         NOT NULL    DEFAULT 1, --  step ( span )  

1. Create a function --- Get current value （v_seq_name Parameter values Represents the name of the sequence ）

create function currval(v_seq_name VARCHAR(50))     
returns integer    
begin        
    declare value integer;         
    set value = 0;         
    select current_val into value  from sequence where seq_name = v_seq_name;   
   return value;   
end;  

select currval(' Sequence name ');  

2. Create a function -- Get the next value （v_seq_name Parameter values Represents the name of the sequence ）

create function nextval (v_seq_name VARCHAR(50))  
    returns integer  
begin  
    update sequence set current_val = current_val + increment_val  where seq_name = v_seq_name;  
    return currval(v_seq_name);  
end;  

select nextval(' Sequence name ');  

select nextval(' Sequence name ');