Mysql limitÓ÷¨
1.SELECT
*
from
table
LIMIT
1
,
20
;
//
¼ìË÷¼Ç¼ÐÐ
2-21
µÚÒ»¸ö²ÎÊý£º²éѯÆðʼÐУ¨´Ó0¿ªÊ¼£©
µÚ¶þ¸ö²ÎÊý£º²éѯ¼¸Ìõ¼Ç¼
2.
SELECT
*
from
table
LIMIT
5
,
-
1
;
//
¼ìË÷¼Ç¼ÐÐ
6
-
last.
3.
SELECT
*
from
table
LIMIT
5
;
//
¼ìË÷ǰ
5
¸ö¼Ç¼ÐÐ
Ïà¹ØÎĵµ£º
תÌûÇë×¢Ã÷³ö´¦£¬²¢±£³ÖÎÄÕµÄÍêÕûÐÔ¡£
¶ÔMySQLÊý¾Ý¿âÀ´Ëµ£¬Í¬Ò»Ê±¿Ì£¬ÔÚͬһ¸öÁ¬½Ó£¨connection£©ÉÏ£¬Ö»ÔÊÐí½øÐÐÒ»¸ö²Ù×÷£¨query£¬etc.£©£¬Èç¹ûÄãµÄ³ÌÐòÊǶàÏ̵߳쬲¢ÇÒÄãÔÚ¶à¸öÏß³ÌÖж¼»áÀûÓÃͬһ¸öconnection¶ÔÊý¾Ý¿â½øÐвÙ×÷£¬ÄÇô£¬¾ÍÓпÉÄÜ·¢ÉúÎÊÌâ¡£
ÀýÈ磬Äã¿ÉÄÜ»áÊÕµ½“Commands out of sync”µÄ´íÎó ......
ʹÓÃmysqlʱ£¬Í¨³£±íÖлáÓÐÒ»¸ö×ÔÔöµÄid×ֶΣ¬µ«µ±ÎÒÃÇÏ뽫±íÖеÄÊý¾ÝÇå¿ÕÖØÐÂÌí¼ÓÊý¾Ýʱ£¬Ï£ÍûidÖØÐ´Ó1¿ªÊ¼¼ÆÊý£¬ÓÃÒÔÏÂÁ½ÖÖ·½·¨¾ù¿É£º
·½·¨Ò»£º
alter table tablename drop column id;
alter table tablename add id mediumint(8) not null primary key auto_increment first;
·½·¨¶þ£º
alter table tab ......
Ò»¹²ÓÐÈý¸öÀࣺWriteFile ; ReadFile ; InsertDB ;
//WriteFile.java
//ÓÃÓÚ½«ÐÅϢдÈëÎı¾Îļþ
package org.mb.insertfromfile;
import java.io.*;
public class WriteFile{
private int count = 0 ;
public int getCount() {
return count;
}
public void setCount(int count) {
this.cou ......
ÔÚÉè¼Æ¹ØÏµÊý¾Ý¿âʱÊÇÒª×ñÊØÒ»¶¨µÄ¹æÔòµÄ¡£ÓÈÆäÊÇÊý¾Ý¿âÉè¼Æ·¶Ê½ÏÖ¼òµ¥½éÉÜ1NF£¨µÚÒ»·¶Ê½£©£¬2NF£¨µÚ¶þ·¶Ê½£©£¬3NF£¨µÚÈý·¶Ê½£©ºÍBCNF£¬ÁíÓеÚËÄ·¶Ê½ºÍµÚÎ巶ʽÁôµ½ÒÔºóÔÙ½éÉÜ¡£ÔÚÄãÉè¼ÆÊý¾Ý¿â֮ʱ£¬ÈôÄÜ·ûºÏÕ⼸¸ö·¶Ê½£¬Äã¾ÍÊÇÊý¾Ý¿âÉè¼ÆµÄ¸ßÊÖ¡£
µÚÒ»·¶Ê½£¨1NF£©£ºÔÚ¹ØÏµÄ£Ê½RÖеÄÿһ¸ö¾ßÌå¹ØÏµrÖУ¬Èç¹ûÿ¸öÊôÐÔÖµ¶¼Ê ......