常用数据库分页语句及数据库编程

取出sql表中第31到40的记录（以自动增长ID为主键）

sql server方案1：
select top 10 * from t where id not in (select top 30 id from t order by id ) orde by id
sql server方案2：
select top 10 * from t where id in (select top 40 id from t order by id) order by id desc

mysql方案：select * from t order by id limit 30,10

oracle方案：select * from (select rownum r,* from t where r<=40) where r>30

1.分页技术1（直接利用sql语句进行分页，效率最高和最推荐的）

pageSize=20;

pageNo = 5;

mysql:sql = "select * from articles limit " + (pageNo-1)*pageSize + "," + pageSize;
oracle: sql = "select * from " +
"(select rownum r,* from " +
"(select * from articles order by postime desc)" +
"where rownum<= " + pageNo*pageSize +") tmp " +
"where r>" + (pageNo-1)*pageSize;
注释：第7行保证rownum的顺序是确定的，因为oracle的索引会造成rownum返回不同的值
简洋提示：没有order by时，rownum按顺序输出，一旦有了order by，rownum不按顺序输出了，这说明rownum是排序前的编号。如果对order by从句中的字段建立了索引，那么，rownum也是按顺序输出的，因为这时候生成原始的查询结果集时会参照索引表的顺序来构建。

sqlserver:sql = "select top 10 * from id not id(select top " + (pageNo-1)*pageSize + "id from articles)"

DataSource ds = new InitialContext().lookup(jndiurl);
Connection cn = ds.getConnection();
PreparedStatement pstmt = cn.prepareSatement(sql);
ResultSet rs = pstmt.executeQuery()
while(rs.next())
{
out.println(rs.getString(1));
}

2.不可滚动的游标

pageSize=20;
pageNo = 5;

cn = null
stmt = null;
rs = null;
try
{
sqlserver:sql = "select * from articles";

DataSource ds = new InitialContext().lookup(jndiurl);
Connection cn = ds.getConnection();
PreparedStatement pstmt = cn.prepareSatement(sql);
ResultSet rs = pstmt.executeQuery()
for(int j=0;j<(pageNo-1)*pageSize;j++)
{
rs.next();
}

int i=0;

while(rs.next() && i<10)
{
i++;
out.println(rs.getString(1));
}
}
cacth(){}
finnaly
{
if(rs!=null)try{rs.close();}catch(Exception e){}
if(stm.........
if(cn............
}

3.可滚动的游标

pageSize=20;
pageNo = 5;

cn = null
stmt = null;
rs = null;
try
{
sqlserver:sql = "select * from articles";

DataSource ds = new InitialContext().lookup(jndiurl);
Connection cn = ds.getConnection();
PreparedStatement pstmt = cn.prepareSatement(sql,ResultSet.TYPE_SCROLL_INSENSITIVE,...);
//根据上面这行代码的异常SQLFeatureNotSupportedException，就可判断驱动是否支持可滚动游标

ResultSet rs = pstmt.executeQuery()
rs.absolute((pageNo-1)*pageSize)
int i=0;
while(rs.next() && i<10)
{
i++;
out.println(rs.getString(1));
}
}
cacth(){}
finnaly
{
if(rs!=null)try{rs.close();}catch(Exception e){}
if(stm.........
if(cn............
}