PolarDB:.NET

Entity Framework

Entity Framework is a popular object-relational mapping (ORM) framework for the .NET platform. When you write back-end applications in C#, Entity Framework and Language-Integrated Query (LINQ) can significantly accelerate development.

The PolarDB .NET driver provides DLLs that support Entity Framework 5 (EF5) and Entity Framework 6 (EF6).

For more information about Entity Framework, see the official Entity Framework website.

Install the .NET driver

1. Download the .NET driver.

2. Unzip the .NET driver package.

   unzip polardb_oracle_.net.zip

3. Import the driver into your Visual Studio project.

   1. In the Visual Studio UI, right-click your project and select Add Reference.

   2. In the Reference Manager dialog box, click Browse.

      Use the Browse... button to select the files to reference.

   3. In the Select the files to reference dialog box, select the appropriate driver version and click Add.

      For example, if you are using .NET Framework 4.5 (the net45 folder), you must reference four DLL files: PolarDB.PolarDBClient.dll, System.Runtime.CompilerServices.Unsafe.dll, System.Threading.Tasks.Extensions.dll, and System.ValueTuple.dll.

   4. Click OK.

Example

Follow these steps to run the sample projects.

1. Connect to the database cluster. For more information, see Connect to a database cluster.

2. Run the following command to create a database named sampledb.

   CREATE DATABASE sampledb;

3. Import the tables, data, and functions required for the sample into the sampledb database.

   \i ${your path}/PolarDBSample.sql

4. After the data is imported, you can start to write your C# code.

   Below is an example of how to query, update, and call stored procedures.

   using System;
   using System.Data;
   using PolarDB.PolarDBClient;
   /*
    * This class provides a simple way to perform DML operations in PolarDB
    *
    * @revision 1.0
    */
   namespace PolarDBClientTest
   {
       class SAMPLE_TEST
       {
           static void Main(string[] args)
           {
               PolarDBConnection conn = new PolarDBConnection("Server=localhost;Port=5432;User Id=polaruser;Password=password;Database=sampledb");
               try
               {
                   conn.Open();
                   //Simple select statement using PolarDBCommand object
                   PolarDBCommand PolarDBSeletCommand = new PolarDBCommand("SELECT EMPNO,ENAME,JOB,MGR,HIREDATE FROM EMP",conn);
                   PolarDBDataReader SelectResult =  PolarDBSeletCommand.ExecuteReader();
                   while (SelectResult.Read()) 
                   {
                       Console.WriteLine("Emp No" + " " + SelectResult.GetInt32(0));
                       Console.WriteLine("Emp Name" + " " + SelectResult.GetString(1));
                       if (SelectResult.IsDBNull(2) == false)
                           Console.WriteLine("Job" + " " + SelectResult.GetString(2));
                       else
                           Console.WriteLine("Job" + " null ");
                       if (SelectResult.IsDBNull(3) == false)
                           Console.WriteLine("Mgr" + " " + SelectResult.GetInt32(3));
                       else
                           Console.WriteLine("Mgr" + "null");
                       if (SelectResult.IsDBNull(4) == false)
                           Console.WriteLine("Hire Date" + " " + SelectResult.GetDateTime(4));
                       else
                           Console.WriteLine("Hire Date" + " null");
                       Console.WriteLine("---------------------------------");
                   }
                   //Insert statement using PolarDBCommand Object
                   SelectResult.Close();
                   PolarDBCommand PolarDBInsertCommand = new PolarDBCommand("INSERT INTO EMP(EMPNO,ENAME) VALUES((SELECT COUNT(EMPNO) FROM EMP),'JACKSON')",conn);
                   PolarDBInsertCommand.ExecuteScalar();
                   Console.WriteLine("Record inserted");
                   //Update  using PolarDBCommand Object
                   PolarDBCommand  PolarDBUpdateCommand = new PolarDBCommand("UPDATE EMP SET ENAME ='DOTNET' WHERE EMPNO < 100",conn);
                   PolarDBUpdateCommand.ExecuteNonQuery();
                   Console.WriteLine("Record has been updated");
                   PolarDBCommand PolarDBDeletCommand = new PolarDBCommand("DELETE FROM EMP WHERE EMPNO < 100",conn);
                   PolarDBDeletCommand.CommandType= CommandType.Text;
                   PolarDBDeletCommand.ExecuteScalar();
                   Console.WriteLine("Record deleted");
                   //procedure call example
                   try
                   {
                       PolarDBCommand callable_command = new PolarDBCommand("emp_query(:p_deptno,:p_empno,:p_ename,:p_job,:p_hiredate,:p_sal)", conn);
                       callable_command.CommandType = CommandType.StoredProcedure;
                       callable_command.Parameters.Add(new PolarDBParameter("p_deptno",PolarDBTypes.PolarDBDbType.Numeric,10,"p_deptno",ParameterDirection.Input,false ,2,2,System.Data.DataRowVersion.Current,20));
                       callable_command.Parameters.Add(new PolarDBParameter("p_empno", PolarDBTypes.PolarDBDbType.Numeric,10,"p_empno",ParameterDirection.InputOutput,false ,2,2,System.Data.DataRowVersion.Current,7369));
                       callable_command.Parameters.Add(new PolarDBParameter("p_ename", PolarDBTypes.PolarDBDbType.Varchar,10,"p_ename",ParameterDirection.InputOutput,false ,2,2,System.Data.DataRowVersion.Current,"SMITH"));
                       callable_command.Parameters.Add(new PolarDBParameter("p_job", PolarDBTypes.PolarDBDbType.Varchar,10,"p_job",ParameterDirection.Output,false ,2,2,System.Data.DataRowVersion.Current,null));
                       callable_command.Parameters.Add(new PolarDBParameter("p_hiredate", PolarDBTypes.PolarDBDbType.Date,200,"p_hiredate",ParameterDirection.Output,false ,2,2,System.Data.DataRowVersion.Current,null));
                       callable_command.Parameters.Add(new PolarDBParameter("p_sal", PolarDBTypes.PolarDBDbType.Numeric,200,"p_sal",ParameterDirection.Output,false ,2,2,System.Data.DataRowVersion.Current,null));
                       callable_command.Prepare();
                       callable_command.Parameters[0].Value = 20;
                       callable_command.Parameters[1].Value = 7369;
                       PolarDBDataReader result = callable_command.ExecuteReader();
                       int fc = result.FieldCount;
                       for(int i=0;i<fc;i++)
                           Console.WriteLine("RESULT["+i+"]="+ Convert.ToString(callable_command.Parameters[i].Value));
                       result.Close();
                   }
                   // If you are using the .NET 2.0 driver, you may need to modify this section.
                   catch(PolarDBException exp)
                   {
                       if(exp.ErrorCode.Equals("01403"))
                           Console.WriteLine("No data found");
                       else if(exp.ErrorCode.Equals("01422"))
                           Console.WriteLine("More than one row was returned by the query");
                       else
                           Console.WriteLine("There was an error calling the procedure. \nRoot Cause:\n");
                       Console.WriteLine(exp.Message.ToString());
                   }
                   //Prepared statement
                   string updateQuery  = "update emp set ename = :Name where empno = :ID";
                   PolarDBCommand Prepared_command = new PolarDBCommand(updateQuery, conn);
                   Prepared_command.CommandType = CommandType.Text;
                   Prepared_command.Parameters.Add(new PolarDBParameter("ID", PolarDBTypes.PolarDBDbType.Integer));
                   Prepared_command.Parameters.Add(new PolarDBParameter("Name", PolarDBTypes.PolarDBDbType.Text));
                   Prepared_command.Prepare();
                   Prepared_command.Parameters[0].Value = 7369;
                   Prepared_command.Parameters[1].Value = "Mark";
                   Prepared_command.ExecuteNonQuery();
                   Console.WriteLine("Record Updated...");
               }
               catch(PolarDBException exp)
               {
                   Console.WriteLine(exp.ToString() );
               }
               finally
               {
                   conn.Close();
               }
           }
       }
   }

Connection string parameters

When your application connects to a database, it must provide a connection string that contains parameters such as the host, username, and password.

The format for a connection string is keyword1=value; keyword2=value;. Keywords are not case-sensitive. Enclose values that contain special characters, such as a semicolon, in double quotation marks ("").

This driver supports the following connection string parameters.