PolarDB:.NET

Entity Framework

Using Entity Framework and Language-Integrated Query (LINQ) can significantly accelerate the development of C# backend applications.

The PolarDB .NET driver provides the EF5 and EF6 .dll files for use with Entity Framework.

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

Install the .NET driver

1. Download the .NET driver.

2. Decompress the .NET driver package.

   unzip polardb_oracle_.net.zip

3. Import the driver into your Visual Studio project.

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

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

      

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

      

   4. Click OK.

Example

The Samples directory contains a PolarDBSample.sql file and several sample project files. The following steps show you how to run these sample projects.

1. Connect to the database. 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 sample schema and data into the sampledb database.

   \i ${your path}/PolarDBSample.sql

4. After the data is imported, you can start writing C# code.

   The following sample code shows how to perform queries, updates, and stored procedure calls.

   using System;
   using System.Data;
   using PolarDB.PolarDBClient;
   /*
    * This class demonstrates how 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("---------------------------------");
                   }
   
                   // Executes an INSERT statement using a 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");
   
                   // Updates a record using a 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 must modify this section accordingly.
                   catch(PolarDBException exp)
                   {
                       if(exp.ErrorCode.Equals("01403"))
                           Console.WriteLine("No data found");
                       else if(exp.ErrorCode.Equals("01422"))
                           Console.WriteLine("Multiple rows were 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

An application connects to a database by providing a connection string that includes parameters such as the host, username, and password.

A connection string uses the keyword1=value; keyword2=value; format and is not case-sensitive. Use double quotation marks ("") to enclose values that contain special characters, such as a semicolon.

The following tables describe the connection string parameters supported by this driver.