我使用 Oracle 数据库作为我的后端。对于我的工作流程，我正在根据用户选择的内容构建动态查询。此动态查询从 5 个不同的表中获取。我正在从所有 5 个表中获取并读取所有列，这样我也可以在其他地方使用相同的逻辑。
Oracle.ManagedDataAccess.dll用于数据库访问。
代码：
public class ClassEx
{
public ClassA ClassA { get; set; }
public ClassB ClassB { get; set; }
public ClassC ClassC { get; set; }
public ClassD ClassD { get; set; }
public ClassE ClassE { get; set; }
public List<ClassEx> Select()
{
List<ClassEx> ex = new List<ClassEx>();
string sql = "Select " + (new ClaasA()).GetFullString("a") + ", "
+ (new ClaasB()).GetFullString("b") + ", "
+ (new ClaasC()).GetFullString("c") + ", "
+ (new ClaasD()).GetFullString("d") + ", "
+ (new ClaasE()).GetFullString("e") +
" From Sysadm.TableA a, Sysadm.TableB b, Sysadm.TableC c, Sysadm.TableD d, Sysadm.TableE e" +
" Where a.Col1 = b.Col2" +
" And a.Col5 = c.Col2" +
" And a.Col6 = d.Col2" +
" And a.Col10 = e.Col2";
GenericDataReader dr = new GenericDataReader(sql);
while(dr.Read())
{
ClassEx dummy = new ClassEx();
dummy.ClassA = new ClassA(dr);
dummy.ClassB = new ClassB(dr);
dummy.ClassC = new ClassC(dr);
dummy.ClassD = new ClassD(dr);
dummy.ClassE = new ClassE(dr);
ex.Add(dummy);
}
return ex;
}
}
public ClassA
{
public int Col1 {get;set;}
...
public DateTime? Col30 {get;set;}
public ClassA(GenericDataReader dr)
{
Col1 = dr.GetInt("A_Col1")
Col2 = dr.GetString("A_Col2")
....
Col30 = dr.GetDateTime("A_Col30")
}
public string GetFullString(string alias)
{
if (!String.IsNullOrEmpty(alias))
alias = alias + ".";
return alias + "A_Col1, " +
alias + "A_Col2, " +
...
alias + "A_Col30"
}
}
public ClassB
{
public int Col1 {get;set;}
...
public DateTime? Col30 {get;set;}
public ClassB(GenericDataReader dr)
{
Col1 = dr.GetInt("B_Col1")
Col2 = dr.GetString("B_Col2")
....
Col30 = dr.GetDateTime("B_Col30")
}
public string GetFullString(string alias)
{
if (!String.IsNullOrEmpty(alias))
alias = alias + ".";
return alias + "B_Col1, " +
alias + "B_Col2, " +
...
alias + "B_Col30"
}
}
public ClassC
{
public int Col1 {get;set;}
...
public DateTime? Col25 {get;set;}
public ClassC(GenericDataReader dr)
{
Col1 = dr.GetInt("C_Col1")
Col2 = dr.GetString("C_Col2")
....
Col25 = dr.GetDateTime("C_Col25")
}
public string GetFullString(string alias)
{
if (!String.IsNullOrEmpty(alias))
alias = alias + ".";
return alias + "C_Col1, " +
alias + "C_Col2, " +
...
alias + "C_Col25"
}
}
public ClassD
{
public int Col1 {get;set;}
...
public DateTime? Col10 {get;set;}
public ClassD(GenericDataReader dr)
{
Col1 = dr.GetInt("D_Col1")
Col2 = dr.GetString("D_Col2")
....
Col10 = dr.GetDateTime("D_Col10")
}
public string GetFullString(string alias)
{
if (!String.IsNullOrEmpty(alias))
alias = alias + ".";
return alias + "D_Col1, " +
alias + "D_Col2, " +
...
alias + "D_Col10"
}
}
public ClassE
{
public int Col1 {get;set;}
...
public DateTime? Col35 {get;set;}
public ClassE(GenericDataReader dr)
{
Col1 = dr.GetInt("E_Col1")
Col2 = dr.GetString("E_Col2")
....
Col35 = dr.GetDateTime("E_Col35")
}
public string GetFullString(string alias)
{
if (!String.IsNullOrEmpty(alias))
alias = alias + ".";
return alias + "E_Col1, " +
alias + "E_Col2, " +
...
alias + "E_Col35"
}
}
一切正常。查询执行甚至不需要一秒钟。然而，while 循环读取 750 条记录需要 40 秒。这是不可接受的。你能帮我改进while循环吗？我不确定它如何以最快的方式读取所有记录。