SQL分页

 

1、oracle的分页

PageMode类：

public class PageModel {

    private List list;

    private int totalRecords;

    private int pageSize;

    private int pageNo;

    /**
     * 总页数
     * @return
     */
    public int getTotalPages() {
        return (this.totalRecords + this.pageSize - 1)/this.pageSize;
    }

    /**
     * 取得首页
     * @return
     */
    public int getTopPageNo() {
        return 1;
    }

    /**
     * 上一页
     * @return
     */
    public int getPreviousPageNo() {
        if (this.pageNo <= 1){
            return 1;
        }
        return this.pageNo - 1;
    }

    /**
     * 下一页
     * @return
     */
    public int getNextPageNo() {
        if (this.pageNo >= this.getBottomPageNo()) {
            return this.getBottomPageNo();
        }
        return this.pageNo + 1;
    }

    /**
     * 尾页
     * @return
     */
    public int getBottomPageNo() {
        return this.getTotalPages();
    }

    public List getList() {
        return list;
    }

    public void setList(List list) {
        this.list = list;
    }

    public int getTotalRecords() {
        return totalRecords;
    }

    public void setTotalRecords(int totalRecords) {
        this.totalRecords = totalRecords;
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getPageNo() {
        return pageNo;
    }

    public void setPageNo(int pageNo) {
        this.pageNo = pageNo;
    }
}

Oracle分页，SQL语句3层嵌套，Mysql则使用limit完成，更加的方便

select * from
       (
          select rownum rn, t.* from
           (
               select * from t_user where user_id<>'root' order by user_id
           ) t where rownum <=?
       ) where rn>?;

具体分页方法:

/**
 * 分页查询
 * @param pageNo
 * @param pageSize
 * @return
 */
public PageModel findAllUser(int pageNo, int pageSize) {
    StringBuffer sbSql = new StringBuffer();
    sbSql.append("select * from ")
        .append("(")
            .append("select rownum rn, t.* from ")
            .append("(")
                .append("select * from t_user where user_id<>'root' order by user_id ")
                .append(") t where rownum <=?")
        .append(") where rn>?");
    Connection conn = null;
    PreparedStatement pstmt = null;
    ResultSet rs = null;
    PageModel pageModel = null;
    try {
        conn = DB.getConnection();
        pstmt = conn.prepareStatement(sbSql.toString());
        pstmt.setInt(1, pageNo * pageSize);
        pstmt.setInt(2, (pageNo -1)*pageSize);
        rs = pstmt.executeQuery();
        List userList = new ArrayList();
        while (rs.next()) {
            User user = new User();
            user.setUserId(rs.getString("user_id"));
            user.setUserName(rs.getString("user_name"));
            user.setPassword(rs.getString("password"));
            user.setContactTel(rs.getString("contact_tel"));
            user.setEmail(rs.getString("email"));
            user.setCreateDate(rs.getTimestamp("create_date"));
            userList.add(user);
        }
        pageModel = new PageModel();
        pageModel.setPageSize(pageSize);
        pageModel.setPageNo(pageNo);
        pageModel.setList(userList);
        pageModel.setTotalRecords(getTotalRecords(conn));
    }catch(SQLException e) {
        e.printStackTrace();
    }finally {
        DB.close(rs);
        DB.close(pstmt);
        DB.close(conn);
    }
    return pageModel;
}