Csharp/C Sharp/Database ADO.net/Table Schema

Get all table names

using System;
using System.Data;
using System.Data.OleDb;
public class DatabaseInfo {    
 public static void Main () { 
   String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
   OleDbConnection con = new OleDbConnection(connect);
   con.Open();  
   Console.WriteLine("Made the connection to the database");
   Console.WriteLine("Information for each table contains:");
   DataTable tables = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables,new object[]{null,null,null,"TABLE"});
   Console.WriteLine("The tables are:");
   foreach(DataRow row in tables.Rows) 
     Console.Write("  {0}", row[2]);

   con.Close();
 }
}

Get Column data type and name from DataColumn

using System;
using System.Data;
using System.Data.OleDb;
public class DatabaseInfo {    
 public static void Main () { 
   String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
   OleDbConnection con = new OleDbConnection(connect);
   con.Open();  
   Console.WriteLine("Made the connection to the database");
   String cmd = "SELECT * FROM Employee"; 
   OleDbDataAdapter adapter = new OleDbDataAdapter();
   adapter.SelectCommand = new OleDbCommand(cmd, con);
   DataSet ds = new DataSet();
   adapter.Fill(ds, "Employee");
   DataTable item = ds.Tables[0];
   Console.WriteLine("Table name: {0}", item.TableName);
   Console.WriteLine("Its columns are:");
   foreach (DataColumn col in item.Columns)
     Console.WriteLine("{0}\t{1}", col.ColumnName, col.DataType);
   con.Close();
 }
}

Get specified column data type and column name from OleDbSchemaTable

using System;
using System.Data;
using System.Data.OleDb;
public class DatabaseInfo {    
 public static void Main () { 
   String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
   OleDbConnection con = new OleDbConnection(connect);
   con.Open();  
   Console.WriteLine("Made the connection to the database");
   Console.WriteLine("Information for each table contains:");
   DataTable tables = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables,new object[]{null,null,null,"TABLE"});
   DataTable cols = con.GetOleDbSchemaTable(OleDbSchemaGuid.Columns,
         new object[]{null,null,"Employee",null});
   Console.WriteLine("The columns in the Customer table are:");
 
   foreach(DataRow row in cols.Rows) 
     Console.WriteLine("  {0}\t{1}", row[3],(OleDbType)row[11]);
   con.Close();
 }
}

Get table Schema

using System;
using System.Data;
using System.Data.SqlClient;
   class SchemaTable
   {
      static void Main(string[] args)
      {
         string connString = "server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";
         string sql = @"select * from employee";
         SqlConnection conn = new SqlConnection(connString);
         try {
            conn.Open();
            SqlCommand cmd = new SqlCommand(sql, conn);
            SqlDataReader reader = cmd.ExecuteReader();
            DataTable schema = reader.GetSchemaTable();
            foreach (DataRow row in schema.Rows)
            { 
               foreach (DataColumn col in schema.Columns){
                  Console.WriteLine(col.ColumnName + " = " + row[col]);
                  Console.WriteLine("Null value allowed: " + col.AllowDBNull);
               }
            }
            reader.Close();
         } catch(Exception e) {
            Console.WriteLine("Error Occurred: " + e);
         } finally {
            conn.Close();
         }
      }  
   }

How to read a table schema

using System;
using System.Data;
using System.Data.SqlClient;
class SchemaOnlyCommandBehavior
{
  public static void Main()
  {
    SqlConnection mySqlConnection =new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.rumandText ="SELECT ID, FirstName, LastName FROM Employee WHERE ID = 8";
    mySqlConnection.Open();
    SqlDataReader productsSqlDataReader =mySqlCommand.ExecuteReader(CommandBehavior.SchemaOnly);
    DataTable myDataTable = productsSqlDataReader.GetSchemaTable();
    foreach (DataRow myDataRow in myDataTable.Rows)
    {
      Console.WriteLine("\nNew column details follow:");
      foreach (DataColumn myDataColumn in myDataTable.Columns)
      {
        Console.WriteLine(myDataColumn + "= " +
          myDataRow[myDataColumn]);
        if (myDataColumn.ToString() == "ProviderType")
        {
          Console.WriteLine(myDataColumn + "= " +
            ((System.Data.SqlDbType) myDataRow[myDataColumn]));
        }
      }
    }
    productsSqlDataReader.Close();
    mySqlConnection.Close();
  }
}

Read schema information using the FillSchema() method of a DataAdapter object

using System;
using System.Data;
using System.Data.SqlClient;
class FillSchema
{
  public static void Main()
  {
    SqlConnection mySqlConnection =new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.rumandText =
      "SELECT ProductID, ProductName " +
      "FROM Products;" +
      "SELECT OrderID " +
      "FROM Orders;" +
      "SELECT OrderID, ProductID, UnitPrice " +
      "FROM [Order Details];";
    SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
    mySqlDataAdapter.SelectCommand = mySqlCommand;
    DataSet myDataSet = new DataSet();
    mySqlConnection.Open();
    mySqlDataAdapter.FillSchema(myDataSet, SchemaType.Mapped);
    mySqlConnection.Close();
    myDataSet.Tables["Table"].TableName = "Products";
    myDataSet.Tables["Table1"].TableName = "Orders";
    myDataSet.Tables["Table2"].TableName = "Order Details";
    foreach (DataTable myDataTable in myDataSet.Tables)
    {
      Console.WriteLine("\n\nReading from the " +
        myDataTable + "DataTable:\n");
      foreach (DataColumn myPrimaryKey in myDataTable.PrimaryKey)
      {
        Console.WriteLine("myPrimaryKey = " + myPrimaryKey);
      }
      foreach (Constraint myConstraint in myDataTable.Constraints)
      {
        Console.WriteLine("myConstraint.IsPrimaryKey = " + ((UniqueConstraint) myConstraint).IsPrimaryKey);
        foreach (DataColumn myDataColumn in ((UniqueConstraint) myConstraint).Columns)
        {
          Console.WriteLine("myDataColumn.ColumnName = " + myDataColumn.ColumnName);
        }
      }
      foreach (DataColumn myDataColumn in myDataTable.Columns)
      {
        Console.WriteLine("\nmyDataColumn.ColumnName = " + myDataColumn.ColumnName);
        Console.WriteLine("myDataColumn.DataType = " + myDataColumn.DataType);
        Console.WriteLine("myDataColumn.AllowDBNull = " + myDataColumn.AllowDBNull);
        Console.WriteLine("myDataColumn.AutoIncrement = " + myDataColumn.AutoIncrement);
        Console.WriteLine("myDataColumn.AutoIncrementSeed = " + myDataColumn.AutoIncrementSeed);
        Console.WriteLine("myDataColumn.AutoIncrementStep = " + myDataColumn.AutoIncrementStep);
        Console.WriteLine("myDataColumn.MaxLength = " + myDataColumn.MaxLength);
        Console.WriteLine("myDataColumn.ReadOnly = " + myDataColumn.ReadOnly);
        Console.WriteLine("myDataColumn.Unique = " + myDataColumn.Unique);
      }
    }
  }
}