// 指定查詢出的列名
private ActionResult SelectBySelect()
{
DbContext context = new EntityTestEntities3();
var list = context.Set <UserInfoP>().Select(userInfo => userInfo);
return(View(list));
}
// 使用指定的DBContext子類查詢
private ActionResult SelectBySubDBContext()
{
EntityTestEntities3 context = new EntityTestEntities3();
var list = context.UserInfoP;
return(View(list));
}
// 使用LinQ方式查詢
private ActionResult SelectByLinQ()
{
EntityTestEntities3 context = new EntityTestEntities3();
var list = from user in context.UserInfoP
select user;
return(View(list));
}
// 查詢指定的列
private ActionResult SelectSingleColumn()
{
DbContext context = new EntityTestEntities3();
var list = from userInfo in context.Set <UserInfoP>()
select new UserInfoPViewModel
{
UID = userInfo.Uid
};
return(View(list));
}
// 多條件查詢
private ActionResult SelectByMultipleCondition()
{
DbContext context = new EntityTestEntities3();
// 方法查詢
//var list = context.Set<UserInfoP>().Where(u => u.Uid >= 2).Where(u => u.UName.Length > 3).Select(u => u);
// linQ查詢
var list = from userinfo in context.Set <UserInfoP>()
where userinfo.Uid >= 2 && userinfo.UName.Length > 3
select userinfo;
return(View(list));
}
// 單條件查詢
private ActionResult SelectBySimpleCondition()
{
DbContext context = new EntityTestEntities3();
// 方法查詢
//var list = context.Set<UserInfoP>().Where(userinfo => userinfo.Uid > 2).Select(u => u);
// linQ查詢語句
var list = from userinfo in context.Set <UserInfoP>()
where userinfo.Uid > 2
select userinfo;
return(View(list));
}
private ActionResult SelectByInnerJoin()
{
DbContext context = new EntityTestEntities3();
DbSet <NewsInfo> newsInfoSet = context.Set <NewsInfo>();
DbSet <NewsType> newsTypeSet = context.Set <NewsType>();
// 1. 第一種查詢，將資料直接丟到cshtml中，藉由導航屬性選出相對應的資料
var list = from newsInfo in newsInfoSet
select newsInfo;
// 2. 第二種查詢，在cs代碼中將資料拿出來，構建一個新模型
// 這種查詢方式會導致無法查詢，因為newsInfo.NewsType只有一個，並不可以枚舉
//var list2 = from newsInfo in newsInfoSet
// from nType in newsInfo.NewsType
// select new
// {
// nid = newsInfo.nid,
// nTitle = newsInfo.nTitle,
// nType = nType
// };
var list2 = from newsType in newsTypeSet
from newsInfo in newsType.NewsInfo
select new NewsInfoViewModel
{
nid = newsInfo.nid,
nTitle = newsInfo.nTitle,
newsType = newsType.tTitle
};
// 3. 直接利用newsInfo的導航屬性
var list3 = from newsInfo in newsInfoSet
select new NewsInfoViewModel
{
nid = newsInfo.nid,
nTitle = newsInfo.nTitle,
newsType = newsInfo.NewsType.tTitle
};
return(View(list3));
}
