上面三个表要查询出来的已经勾选上的列。中间的message_id包含左右表的message_id,要求查询出的结果不能有重复值,左右表message_text和text的数据类型都是ntext,所以不能用DISTINCT。
或者将下列Sql语句转换成一条:
select Message_index.message_id,Message_index.username,Message_index.date,text_table.Text
from Message_index,text_table
where Message_index.message_id=text_table.message_id
select Message_index.message_id,Message_index.username,Message_index.date,image_table.Message_Text
from Message_index,image_table
where Message_index.message_id=image_table.Message_id
还请能人帮帮忙啊!谢谢啦!SQLselect
或者将下列Sql语句转换成一条:
select Message_index.message_id,Message_index.username,Message_index.date,text_table.Text
from Message_index,text_table
where Message_index.message_id=text_table.message_id
select Message_index.message_id,Message_index.username,Message_index.date,image_table.Message_Text
from Message_index,image_table
where Message_index.message_id=image_table.Message_id
还请能人帮帮忙啊!谢谢啦!SQLselect
select Message_index.message_id,Message_index.username,Message_index.date,text_table.Text,image_table.Message_Text
from Message_index,text_table,image_table
where Message_index.message_id=text_table.message_id AND Message_index.message_id=image_table.Message_id--或者
select Message_index.message_id,Message_index.username,Message_index.date,text_table.Text,image_table.Message_Text
from Message_index
INNER JOIN text_table ON Message_index.message_id=text_table.message_id
INNER JOIN image_table ON Message_index.message_id=image_table.Message_id
from Message_index,text_table
where Message_index.message_id=text_table.message_id
union all
select Message_index.message_id,Message_index.username,Message_index.date,image_table.Message_Text as Text
from Message_index,image_table
where Message_index.message_id=image_table.Message_id
只需在两条查询语句之间添加union all即可,union all使用条件就是字段个数相同,这样就可以把两个查询语句的执行结果合并!不过还是感谢上述提供帮助的回帖者!