[英]DataSet does not support System.Nullable<> exception in c#
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void Form2_Load(object sender, EventArgs e)
{
RST_DBDataContext db = new RST_DBDataContext();
var d = (from s in db.TblSpareParts
select new { s.SPartName, s.SPartCode, s.ModelID, s.SPartLocation, s.SPartActive, s.SPartSalePrice }).ToArray();
CrystalReport1 c = new CrystalReport1();
c.SetDataSource(d);
crystalReportViewer1.ReportSource = c;
}
}
我正在嘗試在sql表中生成水晶報告SPartSalePrice因為在c.SetDataSource(d)上可以為空; 異常來請解決
聚結:
var d = (from s in db.TblSpareParts
select new
{
s.SPartName,
...,
SPartSalePrice = s.SPartSalePrice ?? 0.0,
...
}).ToArray();
條件 (對於空值不是很有用,但對於投影其他值很有用)
SPartSalePrice = s.SPartSalePrice == null ? 0.0 : s.SPartSalePrice,
該字段需要被賦予一個名稱(我保留了原始名稱, SPartSalePrice
),並且替換type
( 0.0
)應該與字段的類型匹配。
也許您的一個對象值是Null。 嘗試類似的東西
private void Form2_Load(object sender, EventArgs e)
{
RST_DBDataContext db = new RST_DBDataContext();
var d = (from s in db.TblSpareParts
select new {
s.SPartName?? DBNull.Value,
s.SPartCode?? DBNull.Value,
s.ModelID ?? DBNull.Value,
s.SPartLocation ?? DBNull.Value,
s.SPartActive ?? DBNull.Value,
s.SPartSalePrice ?? DBNull.Value,
}).ToArray();
CrystalReport1 c = new CrystalReport1();
c.SetDataSource(d);
crystalReportViewer1.ReportSource = c;
}
嘗試這個 :
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void Form2_Load(object sender, EventArgs e)
{
RST_DBDataContext db = new RST_DBDataContext();
var d = (from s in db.TblSpareParts
select new { s.SPartName, s.SPartCode, s.ModelID, s.SPartLocation, s.SPartActive, newPartSalePrice = s.SPartSalePrice == null ? 0 : s.SPartSalePrice }).ToArray();
CrystalReport1 c = new CrystalReport1();
c.SetDataSource(d);
crystalReportViewer1.ReportSource = c;
}
}
你應該在選擇中檢查null
s.SPartSalePrice == null ? 0 : s.SPartSalePrice
如果null為null,則返回0,否則返回0,否則返回值並將其賦值給新變量
newPartSalePrice = s.SPartSalePrice == null ? 0 : s.SPartSalePrice
iF數據類型是String然后
SPartSalePrice =s.SPartSalePrice == null ? "" : s.SPartSalePrice;
如果數據為null則顯示空白,否則顯示數據。
如果數據類型是int則
PartSalePrice = s.SPartSalePrice == null ? 0 : s.SPartSalePrice
如果您只有一個可以為空的屬性,請檢查您的班級:decimal? ,把它放在十進制。 對於那些在聲明中有問號的屬性,只需刪除問號並執行即可。
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