用于Microsoft Access 2010.accdb的SQL连接字符串

Question

I am doing a simple login form using winforms and access 2010 database (.accdb) in C#.

I have the following code and it seems that the connection string is wrong. I have tried searching and found that .Jet is for access 07?? but this doesnt seem to work too. i am an amateur at databases (code referred from msdn). I am having trouble understand which should i use for this example too.

access table name: haha

ID (PK)  |   password
-----------------------
   1     |   testing

        System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb");
        System.Data.SqlClient.SqlCommand comm = new System.Data.SqlClient.SqlCommand();

        comm.CommandText = "SELECT HAHA(*) FROM password";
        comm.CommandType = CommandType.Text;
        comm.Connection = conn;

        conn.Open();

        Object returnValue = comm.ExecuteScalar();
        conn.Close();

        MessageBox.Show((string)returnValue);

edited: the table's name is password, and the field that i want to get the value is ID.

SQL statement i wrote it as : SELECT ID FROM password

and yes, only one record in only one field in the table as the primary key.

anyway the problem is that the program hangs upon execution on the first line
-> Keyword not supported: 'provider'.

so i figured that I have a wrong connection string..

Answer 1

对于Acces数据库（.mdb，.accdb等...），您希望使用OleDbConnection ，而不是SqlConnection（SQL Server），如下所示：

conn = new System.Data.OleDb.OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb")

Answer 2

Edit : as pointed out, for access OleDbConnection should be used, not SqlConnection ...

you can use a much more compact way and also be sure connection is closed and disposed in any possible case even when exceptions are thrown, by using the using statements:

your query text was also, probably wrong as others have suggested...

using (var conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\BC207\test.accdb"))
using (var comm = conn.CreateCommand())
{
    comm.CommandText = "SELECT password FROM HAHA";
    comm.CommandType = CommandType.Text;

    conn.Open();

    var returnValue = comm.ExecuteScalar();

    MessageBox.Show(returnValue.ToString());
}

Edit: are you sure the table HAHA only contains one row? Because the ExecuteScalar returns only one value, if you want to get 1 column but from many records you could use a DataReader or a DataSet...

Answer 3

comm.CommandText = "SELECT HAHA(*) FROM password";

It´s wrong.

"SELECT password FROM HAHA"

Answer 4

Your SQL statement should be,

SELECT * from HAHA

OR

 SELECT [Password] From HAHA

EDIT:

You should change the ConnectionString .