比起 LINQ to SQL，EF 除了提供 LINQ 查询方式, 还提供了 Entity SQL language
ESQL 类似 Hibernate 的 HSQL，ESQL 与SQL 语言的语法相似，以字符串的方式执行
esql的查询结果集 ObjectQuery
ObjectQuery<实体>
myContext context = new myContext();
string esql = "SELECT VALUE DBItemList FROM myContext.DBItemList";
// ObjectQuery<DBItemList> query = new ObjectQuery<DBItemList>(esql, context);
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine(r.NameID);
}
myContext context = new myContext();
string esql = "SELECT VALUE it FROM myContext.DBItemList as it";
// ObjectQuery<DBItemList> query = new ObjectQuery<DBItemList>(esql, context);
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine(r.NameID);
}
ObjectQuery<DbDataRecord>
myContext context = new myContext();
string esql = "SELECT it.NameID FROM myContext.DBItemList as it";
//ObjectQuery<DbDataRecord> query = new ObjectQuery<DbDataRecord>(esql, context);
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine(r["NameID"].ToString());
}
ObjectQuery<简单类型>
myContext context = new myContext();
string esql = "SELECT value count(it.NameID) FROM myContext.DBItemList as it";
// ObjectQuery<int> query = new ObjectQuery<int>(esql, context);
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
myContext context = new myContext();
string esql = "SELECT value it.NameID FROM myContext.DBItemList as it";
// ObjectQuery<int> query = new ObjectQuery<int>(esql, context);
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string n in query)
{
Console.WriteLine(n);
}
esql的使用
可以在
- ObjectQuery的Linq方法,
- 构造ObjectQuery,
- context.CreateQuery返方法,
中使用esql,并得到返回的榄查询结果ObjectQuery
it关键字
[it] 出现在 ESQL 中, 由 ObjectQuery<T>.Name 属性设定，用于标示源查询对象(ObjectQuery)的名称，
类似于 "SELECT * FROM Tab as it WHERE it.ItemValue =14" 。
可以将这个默认值 "it" 改成其他字符串。
myContext context = new myContext();
context.DBItemList.Name = "wxd";
ObjectQuery<DBItemList> list = context.DBItemList.Where("wxd.ItemValue=5");
myContext context = new myContext();
var sql = "SELECT VALUE DBItemList FROM myContext.DBItemList";
var query = new ObjectQuery<DBItemList>(sql, context);
query.Name = "wxd";
ObjectQuery<DBItemList> list = query.Where("wxd.ItemValue=@v", newObjectParameter("v", 5));
value 关键字
value 后只能返回一个成员
myContext context = new myContext();
string esql = "SELECT value AVG(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
3
*/
string esql = "select value it.ItemID from myContext.DBItemList as it";
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string r in query)
{
Console.WriteLine(r);
}
myContext context = new myContext();
string esql = "select value row( it.ItemValue ,it.NameID,'wxd' as wxwinter) from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1},{2}", r["ItemValue"], r["NameID"], r["wxwinter"]);
}
查询参数的使用
myContext context = new myContext();
string esql = "SELECT VALUE it FROM myContext.DBItemList as it where it.ItemValue=@v1 or it.NameID=@v2";
ObjectParameter v1 = new ObjectParameter("v1", 3);
ObjectParameter v2 = new ObjectParameter("v2", "n01");
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql,v1,v2);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}",r.NameID,r.ItemValue);
}
中文字段
使用[]将字段括起来
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.值 ==22.22");
System.Console.WriteLine(query.CommandText);
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}", r.a, r.b, r.c, r.d, r.e, r.值);
}
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.[值] ==22.22");
System.Console.WriteLine(query.CommandText);
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}", r.a, r.b, r.c, r.d, r.e, r.值);
}
得到esql与sql字串
myContext context = new myContext();
string esql = "SELECT VALUE it FROM myContext.DBItemList as it";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
Console.WriteLine(query.CommandText);
Console.WriteLine(query.ToTraceString())
SELECT VALUE it FROM myContext.DBItemList as it
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
CommandText属性
得到esql字串
ToTraceString方法
得到sql字串
ObjectQuery的Linq方法
Where
用字符串为条件进行查询
ObjectQuery<T> Where(string predicate, params ObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DBItemList> list = context.DBItemList.Where("(it.ItemValue=5 or it .ItemValue=5) and it.NameID='n01'");
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
WHERE (([Extent1].[ItemValue] = 5) OR ([Extent1].[ItemValue] = 5)) AND([Extent1].[NameID] = 'n01')
OrderBy
排序
ObjectQuery<T> OrderBy(string keys, params ObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.OrderBy("it.ItemValue,it.ItemID desc");
foreach (var r in query)
{
Console.WriteLine("{0},{1},{2},{3}", r.AutoId, r.ItemID, r.NameID, r.ItemValue);
}
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
ORDER BY [Extent1].[ItemValue] ASC, [Extent1].[ItemID] DESC
Select
射影
ObjectQuery<DbDataRecord> Select(string projection, params ObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DbDataRecord> list = context.DBItemList.Select(" it.ItemValue as a,it.NameID ");
SELECT
1 AS [C1],
[Extent1].[ItemValue] AS [ItemValue],
[Extent1].[NameID] AS [NameID]
FROM [dbo].[DBItemList] AS [Extent1]
SelectValue(projection)
返回只有一组字段的数组
ObjectQuery<TResultType> SelectValue<TResultType>(string projection, paramsObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<int> query = context.DBItemList.SelectValue<int>("it.ItemValue + it.AutoID");
foreach (var r in query)
{
Console.WriteLine(r);
}
SELECT
[Extent1].[ItemValue] + [Extent1].[AutoId] AS [C1]
FROM [dbo].[DBItemList] AS [Extent1]
Top(count)
集合的前n个元素
count : 前n个元素
ObjectQuery<T> Top(string count, params ObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Top("3"); ;
foreach (var r in query)
{
Console.WriteLine("{0},{1},{2},{3}", r.AutoId, r.ItemID, r.NameID, r.ItemValue);
}
SELECT TOP (3)
[c].[AutoId] AS [AutoId],
[c].[NameID] AS [NameID],
[c].[ItemID] AS [ItemID],
[c].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [c]
Skip(keys,count)
跳过集合的前n个元素,
keys : 用于排序的字段
count : 要跳过的记录个数
ObjectQuery<T> Skip(string keys, string count, params ObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Skip("it.ItemValue", "5");
foreach (var r in query)
{
Console.WriteLine("{0},{1},{2},{3}", r.AutoId, r.ItemID, r.NameID, r.ItemValue);
}
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM ( SELECT [Extent1].[AutoId] AS [AutoId], [Extent1].[NameID] AS[NameID], [Extent1].[ItemID] AS [ItemID], [Extent1].[ItemValue] AS[ItemValue], row_number() OVER (ORDER BY [Extent1].[ItemValue] ASC) AS[row_number]
FROM [dbo].[DBItemList] AS [Extent1]
) AS [Extent1]
WHERE [Extent1].[row_number] > 5
ORDER BY [Extent1].[ItemValue] ASC
分页 Skip Top
Skip与Top一起使用
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Skip("it.ItemValue", "5").Top("3"); ;
foreach (var r in query)
{
Console.WriteLine("{0},{1},{2},{3}", r.AutoId, r.ItemID, r.NameID, r.ItemValue);
}
SELECT TOP (3)
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM ( SELECT [Extent1].[AutoId] AS [AutoId], [Extent1].[NameID] AS[NameID], [Extent1].[ItemID] AS [ItemID], [Extent1].[ItemValue] AS[ItemValue], row_number() OVER (ORDER BY [Extent1].[ItemValue] ASC) AS[row_number]
FROM [dbo].[DBItemList] AS [Extent1]
) AS [Extent1]
WHERE [Extent1].[row_number] > 5
ORDER BY [Extent1].[ItemValue] ASC
GroupBy(keys,projection)
分组
keys: GROUP BY的字段
projection : Select 的内容
ObjectQuery<DbDataRecord> GroupBy(string keys, string projection, paramsObjectParameter[] parameters);
myContext context = new myContext();
ObjectQuery<DbDataRecord> query = context.DBItemList.GroupBy("it.ItemID","it.ItemID,Sum(it.ItemValue) as ValueSum");
foreach (var r in query)
{
Console.WriteLine("{0},{1}", r["ItemID"], r["ValueSum"]);
}
/*
a,23
b,8
c,23
*/
SELECT
1 AS [C1],
[GroupBy1].[K1] AS [ItemID],
[GroupBy1].[A1] AS [C2]
FROM ( SELECT
[Extent1].[ItemID] AS [K1],
SUM([Extent1].[ItemValue]) AS [A1]
FROM [dbo].[DBItemList] AS [Extent1]
GROUP BY [Extent1].[ItemID]
) AS [GroupBy1]
SELECT it.ItemID,Sum(it.ItemValue) as ValueSum
FROM ( [DBItemList] ) AS it
GROUP BY it.ItemID
Include(path)
加载关联数据,参数为实体的[导航属性]的字串,调用Include("导航属性")后,关联数据会加载,这样就不用在[实体.导航属性]上调用Load()方法
ObjectQuery<T> Include(string path);
myContext context = new myContext();
var r = context.DBItem.Include("DBItemList");
foreach (var dbitem in r)
{
foreach (var dbitemlist in dbitem.DBItemList)
{
Console.WriteLine("{0},{1}", dbitemlist.NameID, dbitemlist.ItemValue);
}
}
效果与下例相同
myContext context = new myContext();
var r = context.DBItem;
foreach (var dbitem in r)
{
dbitem.DBItemList.Load();
foreach (var dbitemlist in dbitem.DBItemList)
{
Console.WriteLine("{0},{1}", dbitemlist.NameID, dbitemlist.ItemValue);
}
}
esql注释,成员访问,分行
注释
--
成员访问
.
分行
;
esql运算符
算术运算符
加
+
减
-
乘
*
除
/
模
%
负
-
比效运算符
等于
=
大于
>
大于等于
>=
空判断
IS NOT NULL
IS NULL
小于
<
小天等于
<=
不等于
!=
<>
字符比效
LIKE ''
NOT LIKE ''
% :
_ :
[ ] :
[^] :
逻辑运算符
与
AND
&&
非
NOT
!
或
OR
||
区间
BETWEEN
之间
BETWEEN n AND m
NOT BETWEEN n AND m
myContext context = new myContext();
string esql = "SELECT VALUE it FROM [DBItemList] AS it WHERE it.ItemValue BETWEEN 2 and 4";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Where(" it.ItemValue not BETWEEN 2 and 4");
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
IN
在集合中
IN {v,v}
NOT IN{v,v}
myContext context = new myContext();
string esql = "SELECT VALUE it FROM [DBItemList] AS it WHERE it.ItemValue IN {1,2,3}";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Where("it.ItemValue not IN {1,2,3}");
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
EXISTS
存在
EXISTS(select from)
NOT EXISTS(select from)
myContext context = new myContext();
string esql = "SELECT VALUE it FROM [DBItemList] AS it WHERE exists(Select VALUE it2 From DBItem as it2 Where it2.ItemID=it.ItemID )";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
myContext context = new myContext();
ObjectQuery<DBItemList> query = context.DBItemList.Where("exists(Select VALUE it2 From DBItem as it2 Where it2.ItemID=it.ItemID )");
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
分页
SELECT VALUE it FROM ( [DBItemList] ) AS it
ORDER BY it.ItemValue
SKIP 5
LIMIT 3
集合运算
Union
(合集)
连接不同集合
UNION --自动过滤相同项
UNION ALL --两个集合的相同项都会返回
myContext context = new myContext();
string esql = "(select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'a' ) UNION (select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'b' )";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
EXCEPT
(左并集)
从集合中删除其与另一个集合中相同的项
myContext context = new myContext();
string esql = "(select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'a' ) EXCEPT (select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'b' )";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
INTERSECT
（交集）
获取不同集合的相同项
myContext context = new myContext();
string esql = "(select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'a' ) INTERSECT (select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID == 'b' )";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
ANYELEMENT
集合中的第一个
myContext context = new myContext();
string esql = "ANYELEMENT(select value it from myContext.DBItemList as it where it.ItemID == 'a') ";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
//如果集合中有两个以上,只返回第一个到集合中
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
SELECT
[Element1].[AutoId] AS [AutoId],
[Element1].[NameID] AS [NameID],
[Element1].[ItemID] AS [ItemID],
[Element1].[ItemValue] AS [ItemValue]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]
LEFT OUTER JOIN (SELECT TOP (1)
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
WHERE [Extent1].[ItemID] = 'a' ) AS [Element1] ON 1 =1
OVERLAPS
两个集合是否有相交部份
myContext context = new myContext();
string esql = "(select value it from myContext.DBItemList as it where it.ItemID == 'c' || it.ItemID=='b' ) OVERLAPS (select value it from myContext.DBItemList as it where it.ItemID == 'a' || it.ItemID=='b')";
ObjectQuery<bool> query = context.CreateQuery<bool>(esql);
foreach (bool r in query)
{
Console.WriteLine(r);
}
//print: True
SELECT
CASE WHEN ( EXISTS (SELECT
cast(1 as bit) AS [C1]
FROM (SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
WHERE ([Extent1].[ItemID] = 'c') OR([Extent1].[ItemID] = 'b')
INTERSECT
SELECT
[Extent2].[AutoId] AS [AutoId],
[Extent2].[NameID] AS [NameID],
[Extent2].[ItemID] AS [ItemID],
[Extent2].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent2]
WHERE ([Extent2].[ItemID] = 'a') OR([Extent2].[ItemID] = 'b')) AS [Intersect1]
)) THEN cast(1 as bit) WHEN ( NOT EXISTS (SELECT
cast(1 as bit) AS [C1]
FROM (SELECT
[Extent3].[AutoId] AS [AutoId],
[Extent3].[NameID] AS [NameID],
[Extent3].[ItemID] AS [ItemID],
[Extent3].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent3]
WHERE ([Extent3].[ItemID] = 'c') OR([Extent3].[ItemID] = 'b')
INTERSECT
SELECT
[Extent4].[AutoId] AS [AutoId],
[Extent4].[NameID] AS [NameID],
[Extent4].[ItemID] AS [ItemID],
[Extent4].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent4]
WHERE ([Extent4].[ItemID] = 'a') OR([Extent4].[ItemID] = 'b')) AS [Intersect2]
)) THEN cast(0 as bit) END AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]
Set
去掉重复项
myContext context = new myContext();
string esql = "set(select value it.ItemID from myContext.DBItemList as it)";
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string r in query)
{
Console.WriteLine(r);
}
//去掉了重复项
SELECT
[Distinct1].[ItemID] AS [ItemID]
FROM ( SELECT DISTINCT
[Extent1].[ItemID] AS [ItemID]
FROM [dbo].[DBItemList] AS [Extent1]
) AS [Distinct1]
esql函数
统计类
Avg
平均值
myContext context = new myContext();
string esql = "SELECT value AVG(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
3
*/
BigCount
个数(long)
myContext context = new myContext();
string esql = "SELECT value BigCount(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<long> query = context.CreateQuery<long>(esql);
foreach (long n in query)
{
Console.WriteLine(n);
}
/* print:
15
*/
Count
个数(int)
myContext context = new myContext();
string esql = "SELECT value Count(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
15
*/
Max
最大值
myContext context = new myContext();
string esql = "SELECT value Max(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
6
*/
Min
最小值
myContext context = new myContext();
string esql = "SELECT value Min(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
1
*/
Sum
合计
myContext context = new myContext();
string esql = "SELECT value Sum(it.ItemValue) FROM myContext.DBItemList as it";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int n in query)
{
Console.WriteLine(n);
}
/* print:
54
*/
联合使用
myContext context = new myContext();
string esql = "SELECT Max(it.ItemValue) as Max , Min(it.ItemValue) as Min FROM myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("Max:{0},Min:{1}", r["Max"], r["Min"]);
}
/* print:
Max:6,Min:1
*/
与group by一起使用
myContext context = new myContext();
string esql = "SELECT ID as ItemID , Max(it.ItemValue) as Max , Min(it.ItemValue) as Min FROM myContext.DBItemList as it group by it.ItemID as ID";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("ItemID:{0}, Max:{1},Min:{2}", r["ItemID"], r["Max"], r["Min"]);
}
/* print:
ItemID:a, Max:6,Min:2
ItemID:b, Max:5,Min:1
ItemID:c, Max:6,Min:2
*/
数学类
Abs
绝对值
Abs(-2)
Round
随机数
Round(748.58)
日期
CurrentDateTime()
CurrentDateTimeOffset()
CurrentUtcDateTime()
Day( expression )
Day(cast('03/12/1998' as DateTime)) --返回:12
GetTotalOffsetMinutes
--返回:
SQL Server 2008 only
Hour ( expression )
Hour(cast('22:35:5' as DateTime)) --返回:22
Minute( expression )
Minute(cast('22:35:5' as DateTime)) --返回:35
Month (expression)
Month(cast('03/12/1998' as DateTime)) --返回:3
Second( expression )
Second(cast('22:35:5' as DateTime)) --返回:5
Year( expression )
Year(cast('03/12/1998' as DateTime)) --返回:1998
字符
Concat ( string1, string2)
字符串连接
Concat('abc', 'xyz') --返回:abcxyz
IndexOf( string1, string2)
字符串位置查找
IndexOf('xyz', 'abcxyz') --返回:4
Length ( string )
字符串长度
Legth('abcxyz') --返回:6
Reverse ( string )
字符串反转
Reverse('abcd') --返回:dcba
ToLower( string )
大写转小写
ToLower('ABC') --返回:abc
ToUpper( string )
小写转大写
ToUpper('abc') --返回:ABC
Trim( string )
去两端空格
Trim(' abc ') --返回:abc
LTrim( string )
去左端空格
LTrim(' abc') --返回:abc
RTrim( string )
去右端空格
Left ( string, length)
左端截取
Left('abcxyz', 3) --返回:abc
Right ( string, length)
右端截取
Right('abcxyz', 3) --返回:xyz
Substring ( string, start, length)
两端截取
Substring('abcxyz', 4, 3) --返回:xyz
esql语句
查询语句
SELECT
myContext context = new myContext();
string esql = "SELECT it.ItemValue as a,it.NameID FROM [DBItemList] AS it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1}", r["a"], r["NameID"]);
}
SELECT
1 AS [C1],
[Extent1].[ItemValue] AS [ItemValue],
[Extent1].[NameID] AS [NameID]
FROM [dbo].[DBItemList] AS [Extent1]
WHERE
myContext context = new myContext();
string esql = "SELECT VALUE it FROM [DBItemList] AS it WHERE (it.ItemValue=5 or it .ItemValue=5) and it.NameID='n01' ";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
WHERE (([Extent1].[ItemValue] = 5) OR ([Extent1].[ItemValue]= 5)) AND ([Extent1].[NameID] = 'n01')
GROUP BY
myContext context = new myContext();
string esql = "SELECT it.ItemID,Sum(it.ItemValue) as ValueSum FROM [DBItemList] AS it GROUP BY it.ItemID ";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1}", r["ItemID"], r["ValueSum"]);
}
SELECT
1 AS [C1],
[GroupBy1].[K1] AS [ItemID],
[GroupBy1].[A1] AS [C2]
FROM ( SELECT
[Extent1].[ItemID] AS [K1],
SUM([Extent1].[ItemValue]) AS [A1]
FROM [dbo].[DBItemList] AS [Extent1]
GROUP BY [Extent1].[ItemID]
) AS [GroupBy1]
ORDER BY
myContext context = new myContext();
string esql = "SELECT VALUE it FROM [DBItemList] AS it ORDER BY it.ItemValue,it.ItemID desc ";
ObjectQuery<DBItemList> query = context.CreateQuery<DBItemList>(esql);
foreach (DBItemList r in query)
{
Console.WriteLine("{0},{1}", r.ItemID, r.ItemValue);
}
SELECT
[Extent1].[AutoId] AS [AutoId],
[Extent1].[NameID] AS [NameID],
[Extent1].[ItemID] AS [ItemID],
[Extent1].[ItemValue] AS [ItemValue]
FROM [dbo].[DBItemList] AS [Extent1]
ORDER BY [Extent1].[ItemValue] ASC, [Extent1].[ItemID] DESC
HAVING
myContext context = new myContext();
string esql = "SELECT it.ItemID,Count(it.ItemValue) as ValueSum FROM DBItemList AS it GROUP BY it.ItemID HAVING SUM(it.ItemValue) > 5";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1}", r["ItemID"], r["ValueSum"]);
}
SELECT
1 AS [C1],
[GroupBy1].[K1] AS [ItemID],
[GroupBy1].[A2] AS [C2]
FROM ( SELECT
[Extent1].[ItemID] AS [K1],
SUM([Extent1].[ItemValue]) AS [A1],
COUNT([Extent1].[ItemValue]) AS [A2]
FROM [dbo].[DBItemList] AS [Extent1]
GROUP BY [Extent1].[ItemID]
) AS [GroupBy1]
WHERE [GroupBy1].[A1] > 5
JOIN
Cross Joins
Inner Joins
Left Outer Joins
Right Outer Joins
Full Outer Joins
CASE语句
CASE WHEN THEN ELSE END
myContext context = new myContext();
string esql = "select it.ItemID, it.ItemValue ,(Case when it.ItemValue =1 then '差' when it.ItemValue between 2 and 4 then '好' else '其他' end) as ItemValueRemarks from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1},{2}", r["ItemID"], r["ItemValue"], r["ItemValueRemarks"]);
}
/*
c,4,好
c,5,其他
c,2,好
c,3,好
b,5,其他
c,6,其他
b,2,好
b,1,差
c,3,好
a,4,好
a,5,其他
a,2,好
a,3,好
a,6,其他
a,3,好
*/
esql 类型
简单类型
Null
is Null
is not Null
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.b is not Null");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
Boolean
True,False
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.e==True");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
Integer
Float,Double
Decimal
123
123.456
23.34
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.c==123");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
String
"abcd"
N"U字符"
'abcd'
myContext context = new myContext();
// ObjectQuery<typeTest> query = context.typeTest.Where("it.b==N'冬冬'");
ObjectQuery<typeTest> query = context.typeTest.Where("it.b==\"冬冬\" ");
// ObjectQuery<typeTest> query = context.typeTest.Where("it.b=='冬冬'");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
DateTime
DATETIME'2007-11-11 22:22'
DATETIME'2007-11-11 01:01:00.0000000'
myContext context = new myContext();
// ObjectQuery<typeTest> query = context.typeTest.Where("it.d==DATETIME'1977-11-11 00:00:00.000'");
ObjectQuery<typeTest> query = context.typeTest.Where("it.d==cast('1977-11-11' as System.DateTime)");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
Time
TIME'22:11'
TIME'01:02:03.1234567'
DateTimeOffset
DATETIMEOFFSET'2007-11-11 22:11 +02:00'
DATETIMEOFFSET'2007-11-11 01:01:00.0000000 -02:00'
Binary
Binary'00ffaabb'
X'ABCabc'
BINARY '0f0f0f0F0F0F0F0F0F0F'
X'' –空
Guid
Guid'0321AF86-0AA5-4a86-A086-1D789FA54AA3'
GUID '0321AF86-0AA5-4a86-A086-1D789FA54AA3'
myContext context = new myContext();
ObjectQuery<typeTest> query = context.typeTest.Where("it.a==Guid'0321af86-0aa5-4a86-a086-1d789fa54aa3'");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
REF
myContext context = new myContext();
//string esql = "SELECT it.ItemID FROM DBItem as it";
string esql = "SELECT REF(it).ItemID FROM DBItem as it";
ObjectQuery<DbDataRecord> v = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in v)
{
Console.WriteLine("{0}", r[0]);
}
ROW
myContext context = new myContext();
string esql = "select value row( it.ItemValue ,it.NameID,'wxd' as wxwinter) from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1},{2}", r["ItemValue"], r["NameID"], r["wxwinter"]);
}
myContext context = new myContext();
string esql = "select row( it.ItemValue ,it.NameID) as wxd ,it.ItemID from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
DbDataRecord v = r["wxd"] as DbDataRecord;
Console.WriteLine("{0},{1},{2}", r["ItemID"],v["ItemValue"],v["NameID"]);
}
集合
MULTISET(1,2,3,4)
{1,2,3,4}
SELECT VALUE it FROM [DBItemList] AS it WHERE it.ItemValue IN {1,2,3}
myContext context = new myContext();
string esql = "{1,2,3} ";
ObjectQuery<int> query = context.CreateQuery<int>(esql);
foreach (int r in query)
{
System.Console.WriteLine(r);
}
SELECT
[UnionAll2].[C1] AS [C1]
FROM (SELECT
[UnionAll1].[C1] AS [C1]
FROM (SELECT
1 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]
UNION ALL
SELECT
2 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable2]) AS[UnionAll1]
UNION ALL
SELECT
3 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable3]) AS[UnionAll2]
myContext context = new myContext();
string esql = "{row(1 as a,'wxd' as wxwinter),row(2 as a,'lzm' as wxwinter),row(3 as a,'wxwinter' as wxwinter)} ";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
System.Console.WriteLine("{0},{1}",r["a"],r["wxwinter"]);
}
/*
1,wxd
2,lzm
3,wxwinter
*/
SELECT
1 AS [C1],
CASE WHEN ([UnionAll2].[C1] = 0) THEN 1 WHEN ([UnionAll2].[C1] = 1) THEN2 ELSE 3 END AS [C2],
CASE WHEN ([UnionAll2].[C1] = 0) THEN 'wxd' WHEN ([UnionAll2].[C1] = 1)THEN 'lzm' ELSE 'wxwinter' END AS [C3]
FROM (SELECT
[UnionAll1].[C1] AS [C1]
FROM (SELECT
0 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]
UNION ALL
SELECT
1 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable2]) AS[UnionAll1]
UNION ALL
SELECT
2 AS [C1]
FROM ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable3]) AS[UnionAll2]
Object 返回对像
Select 选出的值可以直接创建为对像后,将对像放入字段中返回
myContext context = new myContext();
string esql = "SELECT [WindowsFormsApplication8].[DBItemEx](it.ItemID + 'b') as myObject FROM DBItem as it";
ObjectQuery<DbDataRecord> v = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in v)
{
DBItemEx obj = r["myObject"] as DBItemEx;
Console.WriteLine("{0}", obj.ItemID);
}
CAST 类型转换
myContext context = new myContext();
string esql = "select value CAST(it.ItemValue as System.String) from myContext.DBItemList as it";
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string r in query)
{
Console.WriteLine(r);
}
myContext context = new myContext();
string esql = "using System;select value CAST(it.ItemValue as String) from myContext.DBItemList as it";
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string r in query)
{
Console.WriteLine(r);
}
CAST( d as Edm.Decimal(16, 2) )
OFTYPE
OFTYPE ( expression, [ONLY] test_type )
myContext context = new myContext();
string esql = "OFTYPE(((SELECT VALUE it FROM DBItem as it) ),[WindowsFormsApplication8].[DBItemEx])";
ObjectQuery<DBItemEx> v = context.CreateQuery<DBItemEx>(esql);
与如下效果相同
myContext context = new myContext();
ObjectQuery<DBItemEx> v = context.DBItem.OfType<DBItemEx>();
TREAT
myContext context = new myContext();
string esql = "SELECT TREAT(it AS [WindowsFormsApplication8].[DBItemEx]) FROM DBItem AS it";
ObjectQuery<DbDataRecord> v = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in v)
{
DBItemEx obj = r[0] as DBItemEx;
if (obj != null)
{
Console.WriteLine("{0}", obj.ItemID);
}
}
与如下效果类似
myContext context = new myContext();
ObjectQuery<DBItemEx> v = context.DBItem.OfType<DBItemEx>();
IS 类型判断
myContext context = new myContext();
string esql = "SELECT TREAT(it AS [WindowsFormsApplication8].[DBItemEx]) FROM DBItem AS it WHERE it IS OF ([WindowsFormsApplication8].[DBItemEx])";
ObjectQuery<DbDataRecord> v = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in v)
{
DBItemEx obj = r[0] as DBItemEx;
// if (obj != null)
{
Console.WriteLine("{0}", obj.ItemID);
}
}
与如下效果类似
myContext context = new myContext();
ObjectQuery<DBItemEx> v = context.DBItem.OfType<DBItemEx>();
esql Namespace
使用SqlServer函数
using SqlServer;
myContext context = new myContext();
string esql = "using SqlServer;select it.ItemValue ,LEN(it.NameID) as NameIDLEN from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1}",r["ItemValue"],r["NameIDLEN"]);
}
SqlServer.函数
myContext context = new myContext();
string esql = "select it.ItemValue ,SqlServer.LEN(it.NameID) as NameIDLEN from myContext.DBItemList as it";
ObjectQuery<DbDataRecord> query = context.CreateQuery<DbDataRecord>(esql);
foreach (DbDataRecord r in query)
{
Console.WriteLine("{0},{1}",r["ItemValue"],r["NameIDLEN"]);
}
SELECT
1 AS [C1],
[Extent1].[ItemValue] AS [ItemValue],
LEN([Extent1].[NameID]) AS [C2]
FROM [dbo].[DBItemList] AS [Extent1]
使用NET的数据类型
myContext context = new myContext();
string esql = "using System;select value CAST(it.ItemValue as String) from myContext.DBItemList as it";
ObjectQuery<string> query = context.CreateQuery<string>(esql);
foreach (string r in query)
{
Console.WriteLine(r);
}
myContext context = new myContext();
// ObjectQuery<typeTest> query = context.typeTest.Where("it.d==DATETIME'1977-11-11 00:00:00.000'");
ObjectQuery<typeTest> query = context.typeTest.Where("it.d==cast('1977-11-11' as System.DateTime)");
foreach (typeTest r in query)
{
Console.WriteLine("{0},{1},{2},{3},{4},{5}",r.a,r.b,r.c,r.d,r.e,r.值);
}
esql关系,导航
KEY
myContext context = new myContext();
string esql="SELECT VALUE [TargetEntity] FROM (SELECT VALUE x FROM [myContext].[FK_DBItemList_DBItem] AS x WHERE Key(x.[DBItem]) = ROW(@EntityKeyValue1 AS EntityKeyValue1)) AS [AssociationEntry] INNER JOIN [myContext].[DBItemList] AS [TargetEntity] ON Key([AssociationEntry].[DBItemList]) = Key(Ref([TargetEntity]))";
ObjectQuery<DBItemList> dbitemlist = context.CreateQuery<DBItemList>(esql, newObjectParameter("EntityKeyValue1", "a"));
foreach (DBItemList r in dbitemlist)
{
Console.WriteLine("{0},{1},{2}", r.AutoId, r.ItemValue, r.NameID);
}
效果同下
myContext context = new myContext();
ObjectQuery<DBItemList> dbitemlist = context.DBItem.First(p => p.ItemID =="a").DBItemList.CreateSourceQuery();
foreach (DBItemList r in dbitemlist)
{
Console.WriteLine("{0},{1},{2}", r.AutoId, r.ItemValue, r.NameID);
}
