使用insert into table ....select ...的方式插入数据后,table的自增列的值比插入条数要多很多。
例子:
CREATE TABLE test (
jid int(10) unsigned NOT NULL AUTO_INCREMENT,
jnum int(10) unsigned DEFAULT NULL,
PRIMARY KEY (jid)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
-- now: auto_increment = 1
INSERT INTO test(jnum) VALUES (1);
INSERT INTO test(jnum) VALUES (2);
-- now: auto_increment = 3
truncate table test ;
-- now: auto_increment = 1
INSERT INTO test(jnum)
select 1 union
select 2 ;
-- now: auto_increment = 4