MSACCESS日期时间SQL查询

Question

I am from India (it may has something to do with culture info here). I am building a desktop application in C#.Net 2010 Express with MS-ACCESS 2010 32 bit as backend. I am using OLEDB for db connectivity. I have a column named dt as Date/Time which has following values:

20-09-2016 22:53:32
19-08-2016 22:54:24
20-09-2016 22:56:01
22-09-2016 22:56:27
22-09-2016 22:56:41

I need to fetch the records By Date, By Month and By Year. Till now I am not able to complete the Date part so couldnt work on month and year. Following is my code:

b.com.CommandText = "SELECT * FROM srvtrans WHERE DateTime.Parse(dt)=@a ORDER BY sno DESC";
b.com.Parameters.Add("@a", dtp_srdmy.Value.ToShortDateString());
Show(dtp_srdmy.Value.ToShortDateString());
b.con.State == ConnectionState.Closed)
 con.Close();
mytemp = new DataTable();
da.Fill(mytemp);

I have also tried following variations:

WHERE CONVERT(VARCHAR(10),dt,111)=@a

WHERE CONVERT(VARCHAR(10),dt,101)=@a

WHERE dt LIKE '%@a%' 

WHERE DateTime.Parse(dt)=@a 

WHERE dt=DateValue(@a)

WHERE CAST(dt AS DATE)=@a

WHERE CONVERT(varchar, dt, 101)=@a

WHERE DATE(dt)=@a

WHERE dt=@a

but none of them works for me. Please reply what updation should be made in the sql query to fetch records by date, by month and by year. Thanks in advance.

Answer 1

b.com.CommandText = "SELECT * FROM srvtrans WHERE dt = @a ORDER BY sno DESC";
b.com.Parameters.Add(new System.Data.OleDb.OleDbParameter("@a", OleDbType.DBDate) {Value = dtp_srdmy.Value });
con.Open();

• You want to pass in the native types and not string representations of the types for your parameter values. I am assuming that dtp_srdmy is probably a user control ( as pointed out by @Gord Thompson in the comments below probably a DateTimePicker ) or other type where Value is a property that returns a DateTime instance.
• You want to compare directly, the underlying store/provider will handle the comparison for you so do not try to wrap your values in ticks, quotes, or something else or try to do the conversion for the store engine.
• You should specify the underlying access type using the OleDbType enumeration, I guessed it was DBDate but I could be wrong, please correct it if necessary.
• Open your connection before you execute any commands. I assume you are using a data adapter but did not see it, make sure it is associated with your Command. I omitted this part of the code as it was not relevant to the question.

Answer 2

The following code should work definitely:

  b.com.CommandText = "SELECT * FROM srvtrans WHERE DATEVALUE(dt)=DATEVALUE(@a) ORDER BY sno DESC";
  b.com.Parameters.Add("@a", dtp_srdmy.Value);

Upvote if this helps.