/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example23_4.cs illustrates the use of transactions
*/
using System;
using System.Data;
using System.Data.SqlClient;
public class Example23_4
{
public static void Main()
{
// formulate a string containing the details of the
// database connection
string connectionString =
"server=localhost;database=Northwind;uid=sa;pwd=sa";
// create a SqlConnection object to connect to the
// database, passing the connection string to the constructor
SqlConnection mySqlConnection =
new SqlConnection(connectionString);
// open the database connection using the
// Open() method of the SqlConnection object
mySqlConnection.Open();
// step 1: create a SqlTransaction object and start the transaction
// by calling the BeginTransaction() method of the SqlConnection
// object
SqlTransaction mySqlTransaction =
mySqlConnection.BeginTransaction();
// step 2: create a SqlCommand object to hold a SQL statement
SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
// step 3: set the Transaction property for the SqlCommand object
mySqlCommand.Transaction = mySqlTransaction;
// step 4: formulate a string containing the first INSERT statement
string insertString =
"INSERT INTO Customers (" +
" CustomerID, CompanyName, ContactName, Address" +
") VALUES (" +
" 'T2COM', 'T2 Company', 'Jason Price', '1 Main Street'" +
")";
// step 5: set the CommandText property of the SqlCommand object to
// the INSERT string
mySqlCommand.CommandText = insertString;
// step 6: run the first INSERT statement
Console.WriteLine("Running first INSERT statement");
mySqlCommand.ExecuteNonQuery();
// step 7: formulate a second INSERT statement
insertString =
"INSERT INTO Orders (" +
" CustomerID" +
") VALUES (" +
" 'T2COM'" +
")";
// step 8: set the CommandText property of the SqlCommand object to
// the second INSERT string
mySqlCommand.CommandText = insertString;
// step 9: run the second INSERT statement
Console.WriteLine("Running second INSERT statement");
mySqlCommand.ExecuteNonQuery();
// step 10: commit the transaction using the Commit() method
// of the SqlTransaction object
Console.WriteLine("Committing transaction");
mySqlTransaction.Commit();
// close the database connection using the Close() method
// of the SqlConnection object
mySqlConnection.Close();
}
}
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Use of a transaction
using System;
using System.Data;
using System.Data.SqlClient;
class ExecuteTransaction
{
public static void Main()
{
SqlConnection mySqlConnection =new SqlConnection("server=(local)SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
mySqlConnection.Open();
SqlTransaction mySqlTransaction = mySqlConnection.BeginTransaction();
SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
mySqlCommand.Transaction = mySqlTransaction;
mySqlCommand.CommandText =
"INSERT INTO Employee (" +
" ID, FirstName" +
") VALUES (" +
" 10, 'Jason'" +
")";
Console.WriteLine("Running first INSERT statement");
mySqlCommand.ExecuteNonQuery();
mySqlCommand.CommandText =
"INSERT INTO Employee (" +
" ID, FirstName" +
") VALUES (" +
" 11, 'Jason'" +
")";
Console.WriteLine("Running second INSERT statement");
mySqlCommand.ExecuteNonQuery();
Console.WriteLine("Committing transaction");
mySqlTransaction.Commit();
mySqlConnection.Close();
}
}
Set a savepoint in a transaction
using System;
using System.Data;
using System.Data.SqlClient;
class Savepoint {
public static void Main() {
SqlConnection mySqlConnection =
new SqlConnection(
"server=localhost;database=Northwind;uid=sa;pwd=sa"
);
mySqlConnection.Open();
SqlTransaction mySqlTransaction = mySqlConnection.BeginTransaction();
SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
mySqlCommand.Transaction = mySqlTransaction;
mySqlCommand.CommandText =
"INSERT INTO Customers ( " +
" CustomerID, CompanyName " +
") VALUES ( " +
" 'J8COM', 'J8 Company' " +
")";
int numberOfRows = mySqlCommand.ExecuteNonQuery();
Console.WriteLine("Number of rows inserted = " + numberOfRows);
mySqlTransaction.Save("SaveCustomer");
mySqlCommand.CommandText = "INSERT INTO Orders (CustomerID ) VALUES ( 'J8COM' )";
numberOfRows = mySqlCommand.ExecuteNonQuery();
Console.WriteLine("Number of rows inserted = " + numberOfRows);
mySqlTransaction.Rollback("SaveCustomer");
mySqlCommand.CommandText =
"SELECT CustomerID, CompanyName " +
"FROM Customers " +
"WHERE CustomerID = 'J8COM'";
SqlDataReader mySqlDataReader = mySqlCommand.ExecuteReader();
while (mySqlDataReader.Read()) {
Console.WriteLine("mySqlDataReader[" CustomerID"] = " +
mySqlDataReader["CustomerID"]);
Console.WriteLine("mySqlDataReader[" CompanyName"] = " +
mySqlDataReader["CompanyName"]);
}
mySqlDataReader.Close();
mySqlCommand.CommandText = "DELETE FROM Customers WHERE CustomerID = 'J8COM'";
numberOfRows = mySqlCommand.ExecuteNonQuery();
Console.WriteLine("Number of rows deleted = " + numberOfRows);
mySqlTransaction.Commit();
mySqlConnection.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.CommandText ="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("
New 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.CommandText =
"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("
Reading from the " +
myDataTable + "DataTable:
");
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("
myDataColumn.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);
}
}
}
}
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} {1}", col.ColumnName, col.DataType);
con.Close();
}
}