string connString = @"server = (local)/sqlEXPRESS; Initial Catalog=northwind; user id = sa; password = 12345;";
string sql = @"select * from employees";
sqlConnection
l sqlConnection conn = new sqlConnection( connString );
l sqlConnection conn = new sqlConnection();
conn.ConnectionString = connString;
Sample:
string connString = @"server = (local)/sqlEXPRESS; Initial Catalog=northwind; user id = sa; password = 12345;";
sqlConnection conn = new sqlConnection();
conn.ConnectionString = connString;
try
{
conn.open();
Console.WriteLine("Connection opened.");
Console.WriteLine("Connection Properties:");
Console.WriteLine("/tConnection String:{0}",conn.ConnectionString);
Console.WriteLine("/tDatabase:{0}",conn.Database);
Console.WriteLine("/tDataSource:{0}",conn.DataSource);
Console.WriteLine("/tServerVersion:{0}",conn.ServerVersion);
Console.WriteLine("/tState:{0}",conn.State);
Console.WriteLine("/tWorkstationID:{0}",conn.WorkstationId);
}
catch (sqlException e)
{
Console.WriteLine("Error:" + e);
}
finally
{
conn.Close();
Console.WriteLine("Connection closed.");
}
sqlCommand
l sqlCommand cmd = new sqlCommand();
cmd.CommandText = sql;
cmd.Connection = conn;
l sqlCommand cmd = new sqlCommand(@"select * from employees");
l sqlCommand cmd = new sqlCommand(@"select * from employees",conn);
l sqlCommand cmd = new sqlCommand(sql,conn);
l sqlCommand cmd = conn.CreateCommand();
ExecuteNonQuery 返回受影响的行数
ExecuteScalar 单个值，返回第一行第一列的Object类型
ExecuteReader 0个或多个行，返回一个数据读取器，它是sqlDataReader类的一 个实例
ExecuteXmlReader XML
sqlDataReader
不能直接实例化数据读取器，而是通过执行命令对象的ExecuteReader方法创建它的实现。
为了能够把连接用于另一个目的，或在数据库上执行另一查询，调用sqlDataReader的Close方法显示关闭读取器。这是因为，一旦把读取器附着到活动的连接上，连接就会一直忙于为读取器获取数据，而不能用于另一目的，直至端口读取器为止。
Depth() 该属性表示当前行的嵌套深度
FieldCount() 该属性表示结果集中的列数
GetDataTypeName() 这个方法接受索引，返回含有列数据类型名称的字符串
GetFieldType() 这个方法接受索引，返回对象的.NET Frameword数据类型
GetName () 这个方法接受索引，返回指定列的名词
Sample:
string sql = @"select * from employees";
string connString = @"server = (local)/sqlEXPRESS; Initial Catalog = northwind; user id = sa; password = 12345;";
sqlConnection conn = new sqlConnection();
conn.ConnectionString = connString;
sqlCommand cmd = conn.CreateCommand();
sqlDataReader reader = null;
try
{
conn.open();
cmd.CommandText = @"select count(*) from employees";
Console.WriteLine("Number of Employees is: {0}",cmd.ExecuteScalar());
cmd.CommandText = sql;
reader = cmd.ExecuteReader();
//Console.WriteLine("First Name|Last Name");
Console.WriteLine(reader.GetDataTypeName(1).PadLeft(10) + "|" + reader.GetDataTypeName(2));
Console.WriteLine(reader.GetName(1).PadLeft(10) + "|" + reader.GetName(2));//列名
while (reader.Read())
{
Console.WriteLine("{0}|{1}",
reader["FirstName"].ToString().PadLeft(10),
reader["LastName"].ToString().padright(10)
);
}
Console.WriteLine("Number of columns in a row: {0}",reader.FieldCount);
Console.WriteLine("/"FirstName/" is at index {0} and its type is: {1}",
reader.Getordinal("FirstName"),
reader.GetFieldType(reader.Getordinal("FirstName")));
}
catch (sqlException e)
{
Console.WriteLine("Error:" + e);
}
finally
{
reader.Close();
conn.Close();
}
sqlDataAdapter
做为数据源与数据集的桥梁。
l sqlDataAdapter da= new sqlDataAdapter();
l sqlDataAdapter da= new sqlDataAdapter(sql) ;
l sqlDataAdapter da= new sqlDataAdapter(sql,conn);
Sample:
string connString = "Data Source=IBM-2E7EC1F0E54//sqlEXPRESS;Initial Catalog=northwind;User ID=sa;Password=12345";
string sql = @"select productname,unitprice from products where unitprice < 20";
sqlConnection conn = new sqlConnection(connString);
try
{
conn.open();
sqlDataAdapter da= new sqlDataAdapter(sql,conn);
DataSet ds = new DataSet();
da.Fill(ds,"products");
DataTable dt = ds.Tables["products"];
foreach(DaTarow row in dt.Rows)
{
foreach(DataColumn col in dt.Columns)
{
Console.WriteLine(row[col]);
}
Console.WriteLine("".PadLeft(20,'-'));
}
}
catch(sqlException e)
{
Console.WriteLine(e);
}
finally
{
conn.Close();
}
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 [email protected] 举报，一经查实，本站将立刻删除。
