本节内容：
jsp union 数据库的多表分页查询。
例子：
复制代码 代码示例:
sql.append("select obj.objid,");
sql.append(" obj.objname,");
sql.append(" obj.objtype,");
sql.append(" ep.pic_id,");
sql.append(" ep.pic_dir,");
sql.append(" ep.s_file,");
sql.append(" ep.m_file,");
sql.append(" ep.l_file,");
sql.append(" ep.type,");
sql.append(" ep.state,");
sql.append(" ep.create_time");
sql.append(" from ecom_pictures ep,");
sql.append(" (select ec.company_id as objid,");
sql.append(" ec.name as objname,");
sql.append(" ec.pic_id as pic_id,");
sql.append(" 'COMPANY' as objtype");
sql.append(" from ecom_company ec");
sql.append(" union");
sql.append(" select eg.goods_id as ojbid,");
sql.append(" eg.name as objname,");
sql.append(" eg.pic_id as pic_id,");
sql.append(" 'GOODS' as objtype");
sql.append(" from ecom_goods eg");
sql.append(" union");
sql.append(" select eu.user_id as objid,");
sql.append(" eu.name as objname,");
sql.append(" eu.pic_id as pic_id,");
sql.append(" 'USER' as objtype");
sql.append(" from ecom_user eu) obj");
sql.append(" where obj.pic_id = ep.pic_id");
说明：
通过union对四个表做联合查询，如果分页的话，再加上分页条件就可以了。
