C# 林奇;无法强制转换类型为';System.DateTime';输入';System.String'&引用;错误
我正在使用linq从数据库中提取一些信息 Sql脚本:C# 林奇;无法强制转换类型为';System.DateTime';输入';System.String'&引用;错误,c#,linq,oracle,C#,Linq,Oracle,我正在使用linq从数据库中提取一些信息 Sql脚本: TYPE CURS IS REF CURSOR; CREATE OR REPLACE PROCEDURE PROCEDURE_NAME ( Cursor1 OUT CURS) AS BEGIN OPEN Cursor1 FOR SELECT NO, TITLE, TO_CHAR(STARTDATE) STARTDATE
TYPE CURS IS REF CURSOR;
CREATE OR REPLACE
PROCEDURE PROCEDURE_NAME (
Cursor1 OUT CURS)
AS
BEGIN
OPEN Cursor1 FOR
SELECT NO, TITLE, TO_CHAR(STARTDATE) STARTDATE
FROM TABLE_1;
END;
var query = from e in getItem().AsEnumerable()
select new {
No = e.Field<string>("NO"),
Title = e.Field<string>("TITLE"),
StartDate = e.Field<string>("STARTDATE")
};
return query.Select(e => new ClassA()
{
No = e.No,
Title = e.Title,
StartDate = e.StartDate
}).ToList<ClassA>();
public class ClassA {
public string No { get; set; }
public string Title { get; set; }
public string StartDate { get; set; }
}
public DataTable getItem() {
OracleDataAdapter da = new OracleDataAdapter();
DataSet ds = new DataSet();
OracleCommand cmd = new OracleCommand();
cmd.CommandText = "PROCEDURE_NAME";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("Cursor1", OracleDbType.RefCursor).Direction = ParameterDirection.Output;
da.SelectCommand = cmd;
da.Fill(ds);
return ds.Tables[0];
}
Linq代码:
TYPE CURS IS REF CURSOR;
CREATE OR REPLACE
PROCEDURE PROCEDURE_NAME (
Cursor1 OUT CURS)
AS
BEGIN
OPEN Cursor1 FOR
SELECT NO, TITLE, TO_CHAR(STARTDATE) STARTDATE
FROM TABLE_1;
END;
var query = from e in getItem().AsEnumerable()
select new {
No = e.Field<string>("NO"),
Title = e.Field<string>("TITLE"),
StartDate = e.Field<string>("STARTDATE")
};
return query.Select(e => new ClassA()
{
No = e.No,
Title = e.Title,
StartDate = e.StartDate
}).ToList<ClassA>();
public class ClassA {
public string No { get; set; }
public string Title { get; set; }
public string StartDate { get; set; }
}
public DataTable getItem() {
OracleDataAdapter da = new OracleDataAdapter();
DataSet ds = new DataSet();
OracleCommand cmd = new OracleCommand();
cmd.CommandText = "PROCEDURE_NAME";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("Cursor1", OracleDbType.RefCursor).Direction = ParameterDirection.Output;
da.SelectCommand = cmd;
da.Fill(ds);
return ds.Tables[0];
}
getItem():
TYPE CURS IS REF CURSOR;
CREATE OR REPLACE
PROCEDURE PROCEDURE_NAME (
Cursor1 OUT CURS)
AS
BEGIN
OPEN Cursor1 FOR
SELECT NO, TITLE, TO_CHAR(STARTDATE) STARTDATE
FROM TABLE_1;
END;
var query = from e in getItem().AsEnumerable()
select new {
No = e.Field<string>("NO"),
Title = e.Field<string>("TITLE"),
StartDate = e.Field<string>("STARTDATE")
};
return query.Select(e => new ClassA()
{
No = e.No,
Title = e.Title,
StartDate = e.StartDate
}).ToList<ClassA>();
public class ClassA {
public string No { get; set; }
public string Title { get; set; }
public string StartDate { get; set; }
}
public DataTable getItem() {
OracleDataAdapter da = new OracleDataAdapter();
DataSet ds = new DataSet();
OracleCommand cmd = new OracleCommand();
cmd.CommandText = "PROCEDURE_NAME";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("Cursor1", OracleDbType.RefCursor).Direction = ParameterDirection.Output;
da.SelectCommand = cmd;
da.Fill(ds);
return ds.Tables[0];
}
但是查询总是返回错误无法将类型为“System.DateTime”的对象转换为类型为“System.String”。
但是我已经检查了STARTDATE是否提取为System.String。如何解决这个问题?真要命
[更新] 它现在可以工作了,我将STARTDATE的所有数据类型更改为
DateTime
,并从数据库中提取它,而不进行转换
但是,我仍然不理解为什么会出现错误。在存储过程中,删除函数以\u CHAR。此函数将日期时间列转换为varchar2列
TYPE CURS IS REF CURSOR;
CREATE OR REPLACE
PROCEDURE PROCEDURE_NAME (
Cursor1 OUT CURS)
AS
BEGIN
OPEN Cursor1 FOR
SELECT NO, TITLE, STARTDATE
FROM TABLE_1;
END;
为了对这个问题有一个正式的回答,我将在这里发布所有者的答案。(如果所有者将其答案包含在此处,我将删除此内容) [更新]
现在可以工作了,我将STARTDATE的所有数据类型更改为DateTime,并从数据库中提取它,而不进行转换。如果执行
STARTDATE=e.Field(“STARTDATE”)
,会发生什么?这行吗?同样的错误仍然提示出到\u CHAR
是一个返回VARCHAR2
的Oracle方法:可能GetItem()
中的某个东西正在将其转换回日期时间?不确定为什么会这样,但我没有看到您发布的代码有任何其他问题。请将sql中的字段名更改为STARTDATE2,并在代码中相应地更改它,然后查看发生了什么。。