using
System;
using
System.ComponentModel;
using
System.Data;
using
System.Windows.Forms;
namespace
WindowsApplication1
{
public
partial
class
Form1:Form
{
public
Form1()
{
InitializeComponent();
}
private
void
button1_Click(
object
sender,EventArgse)
{
//
System.Data.DataTable計算功能詳解，轉載請保留以下信息
//
測試環境vs2005,c#
//
作者:jinjazz
//
作者blog:
http://blog.csdn.net/jinjazz/
System.Data.DataTabletable
=
new
DataTable();
//
計算常量，可以沒有初始化列
object
test
=
table.Compute(
"
1+1
"
,
""
);
Console.WriteLine(test);
//
test=2;
test
=
table.Compute(
"
1+1
"
,
"
false
"
);
Console.WriteLine(test);
//
test=2;常數計算和filter無關
test
=
table.Compute(
"
abs(1)
"
,
""
);
Console.WriteLine(test);
//
test=null，不知道為這個什么沒有抱錯，而且返回null,其他的數學函數都會抱錯
test
=
table.Compute(
"
2%2
"
,
""
);
Console.WriteLine(test);
//
test=0;
//
其他函數參考下面的計算列
//
初始化datatale
table.Columns.Add(
"
id
"
,
typeof
(
string
));
table.Columns.Add(
"
value
"
,
typeof
(
int
));
for
(
int
i
=
1
;i
<=
10
;i
++
)
{
System.Data.DataRowdRow
=
table.NewRow();
dRow[
"
id
"
]
=
"
id
"
+
i.ToString();
dRow[
"
value
"
]
=
i;
table.Rows.Add(dRow);
}
//
test=table.Compute("value+1","true");
///
/拋出異常，這里必須是聚合函數
//
*************************************支持的聚合函數**********************
//
//
求數量
test
=
table.Compute(
"
count(id)
"
,
"
false
"
);
Console.WriteLine(test);
//
test=0;
test
=
table.Compute(
"
count(id)
"
,
"
true
"
);
Console.WriteLine(test);
//
test=10;
//
求和
test
=
table.Compute(
"
sum(value)
"
,
""
);
Console.WriteLine(test);
//
test=55;
//
test=table.Compute("sum(id)","");
///
/拋出異常，這里不能是string
//
平均
test
=
table.Compute(
"
avg(value)
"
,
""
);
Console.WriteLine(test);
//
test=5;
//
最小
test
=
table.Compute(
"
min(value)
"
,
""
);
Console.WriteLine(test);
//
test=1;
//
最大
test
=
table.Compute(
"
max(value)
"
,
""
);
Console.WriteLine(test);
//
test=10;
//
統計標準偏差
test
=
table.Compute(
"
StDev(value)
"
,
""
);
Console.WriteLine(test);
//
test=3.02765035409749
//
統計方差
test
=
table.Compute(
"
Var(value)
"
,
""
);
Console.WriteLine(test);
//
test=9.16666666666667
//
復雜計算
test
=
table.Compute(
"
max(value)/sum(value)
"
,
""
);
Console.WriteLine(test);
//
test=0.181818181818182
/*
******************************************計算列************************
*/
System.Data.DataColumncolumn
=
new
DataColumn(
"
exp1
"
,
typeof
(
float
));
table.Columns.Add(column);
//
簡單計算
column.Expression
=
"
value*2
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=2;
//
字符串函數
column.Expression
=
"
len(id)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=3;
//
字符串函數
column.Expression
=
"
len(''+id+'')
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=5;
//
字符串函數
column.Expression
=
"
len(trim(''+id+''))
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=3;
//
字符串函數
column.Expression
=
"
substring(id,3,len(id)-2)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=1;
//
substring的起始字符位置為1不是0
//
類型轉換
column.Expression
=
"
convert(substring(id,3,len(id)-2),'System.Int32')*1.6
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=1.6;
//
相當于sqlserver的isnull
column.Expression
=
"
isnull(value,10)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=1;
//
三元運算符,相當于sqlserver的casewhen
column.Expression
=
"
iif(value>5,1000,2000)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=2000;
//
like運算符
column.Expression
=
"
iif(idlike'%1',1000,2000)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=1000;
//
in運算符
column.Expression
=
"
iif(idnotin('id1'),1000,2000)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=2000;
//
嵌套的三元運算
column.Expression
=
"
iif(value>5,1000,iif(idlike'%1',4000,2000))
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=4000;
//
客戶端計算所占總數的百分比
column.Expression
=
"
value/sum(value)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=0.01818182
//
客戶端計算差值,比如nba常規賽的勝場差
column.Expression
=
"
max(value)-value
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=9
//
***********************父子表計算*************************************/
//
初始化子表,父子表關系
DataTabletableChild
=
new
DataTable();
tableChild.Columns.Add(
"
id
"
,
typeof
(
string
));
tableChild.Columns.Add(
"
value
"
,
typeof
(
int
));
System.Data.DataSetds
=
new
DataSet();
ds.Tables.Add(tableChild);
ds.Tables.Add(table);
DataRelationrelation
=
new
DataRelation(
"
relation
"
,table.Columns[
"
id
"
],tableChild.Columns[
"
id
"
]);
ds.Relations.Add(relation);
for
(
int
i
=
1
;i
<=
10
;i
++
)
{
System.Data.DataRowdRow
=
tableChild.NewRow();
dRow[
"
id
"
]
=
"
id1
"
;
dRow[
"
value
"
]
=
i;
tableChild.Rows.Add(dRow);
}
//
計算子表記錄數
column.Expression
=
"
count(child(relation).value)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
test=10;
//
計算父子表的百分比
column.Expression
=
"
value/sum(child(relation).value)
"
;
test
=
table.Select(
"
id='id1'
"
)[
0
][
"
exp1
"
];
Console.WriteLine(test);
//
<
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