MySQL自增-SQL实现

!!!!!!!!!!!!!很重要
MySQL ID自增
create function currval(v_seq_name VARCHAR(50))  
returns VARCHAR(255) 
begin     
    declare value VARCHAR(255);         
    select CONCAT(name,current_val)	into value  from sequence where seq_name = v_seq_name;
   return value;
end;

select currval('seq_test1_num1');


create function nextval (v_seq_name VARCHAR(50))
    returns VARCHAR(255)
begin
    update sequence set current_val = current_val + increment_val  where seq_name = v_seq_name;
    return currval(v_seq_name);
end;


select nextval('seq_test1_num1');


CREATE TABLE `test1` (
  `name` varchar(255) NOT NULL,
  `value` double(255,0) DEFAULT NULL,
  `num1` int(11) DEFAULT NULL,
  `num2` int(11) DEFAULT NULL,
  PRIMARY KEY (`name`)
);


CREATE TRIGGER `TRI_test1_num1` BEFORE INSERT ON `test1` FOR EACH ROW BEGIN
set NEW.num1 = nextval('seq_test1_num1');
set NEW.num2 = nextval('seq_test1_num2');
END


INSERT INTO test1 (name, value) VALUES ('1', '111');
INSERT INTO test1 (name, value) VALUES ('2', '222');

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