一、分页查询
❓ 需求描述:客户端查询数据库数据并显示在表格中。在数据库中进行一次查询,查询结果有1050条记录,但表格row上限: 100,这时需要给本次查询记录分配 ? 页用来显示?
可以通过固定公式进行计算(c伪代码):- # define TABLE_SHOW_ROW 100
- // 在大学学生表student中查询年龄小于19岁的学生信息,并按照日期/时间排序(默认升序)
- char sql_stat[] = {"select stu_id, stu_name, stu_age, stu_sex, date_time from student where stu_age < 19 order by date_time"};
- int num_of_rec = sql_record_total_query(sql_stat);
- char msg_page[1024] = {0};
- int page;
- int quotient= num_of_rec / TABLE_SHOW_ROW;
- int remainder = num_of_rec % TABLE_SHOW_ROW;
- if (num_of_rec > TABLE_SHOW_ROW)
- {
- if (remainder > 0)
- page = quotient + 1;
- else
- page = quotient;
- }
- else
- {
- page = 1;
- }
- // 打印查询结果页面信息
- sprintf(msg_page, "1 of %d", page);
复制代码 上一页和下一页业务逻辑(c伪代码)- int offset_val;
- int page_now = active_page_get(msg_page);
- if (event == click_page_up) // 当客户端点击上一页
- {
- offset_val = (page_now - 1) * TABLE_SHOW_ROW;
- --page_now;
- }
- else if (event == click_page_down) // 当客户端点击下一页
- {
- offset_val = page_now * TABLE_SHOW_ROW;
- ++page_now;
- }
- char sql_stat[1024] = {0};
- sprintf(sql_stat, "select stu_id, stu_name, stu_age, stu_sex, date_time from student "
- "where stu_age < 19 order by date_time "
- "OFFSET %d ROWS FETCH NEXT %d ROWS ONLY", offset_val, TABLE_SHOW_ROW);
- sql_record_get(sql_stat, record);
- table_record_show(record);
- sprintf(msg_page, "%d of %d", page_now, page);
复制代码 二、参考引用
7.3 SQL Server分页查询
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