PetShop DBUtility 类库的学习
ExecuteNonQuery 方法
<方法一>
<Summary>
Execute a SQLCommand (that returns no resultset) against(依照) the database specified in the connection string using the provided parameters.
根据指定的数据库连接参数连接数据库后执行命令
</Summary)
eg.
int result=ExecuteNonQuery(connString,CommandType.StoredProcedure,”PublishOrders”,new SqlParameter(“@prodid”,24));
Paramter:
connectionString-----a valid connection string for a SqlConnection
commandType-----the command type (stored procedure,text,etc.)
commandText-----the stored procedure name or T-SQL command
commandParameters-----an array of SqlParameters used to execute the command
Returns
an int representing the number of rows affected by the command
-------------------------------------------------------------------------------------------------------------------------------------------------
public static int ExecuteNonQuery(string connectionString,CommandType cmdType,string cmdText,params SqlParameter[] commandParameters)
{
SqlCommand cmd=new SqlCommand();
using(SqlConnection conn=new SqlConnection(connectionString)){ //连接用using 语句
PrepareCommand(cmd,conn,null,cmdType,cmdText,commandParameters);
int val=cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
}
<Summary>
Execute a SqlCommand(that returns no resultset) against an existing database connection
在已有连接上执行一条SQL语句命令（不返回结果集）
</Summary>
-------------------------------------------------------------------------------------------------------------------------------------------------
public static int ExecuteNonQuery(SqlConnection connection,CommandType cmdType,string cmdText,params SqlParameter[] commandParameters)
{
SqlCommand cmd=new SqlCommand();
PrepareCommand(cmd,connection,null,cmdType,cmdText,commandParameters);
int val=cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
<方法三>
<Summary>
Execute a SqlCommand (That returns no resultset) using an existing SQL Transaction
在已有的事务中执行一句不返回结果集的语句
</Summary>
-------------------------------------------------------------------------------------------------------------------------------------------------
public static int ExecuteNonQuery(SqlTransaction trans,CommandType cmdType,string cmdText,params SqlParameter[] commandParameters)
{
SqlCommand cmd=new SqlCommand();
PrepareCommand(cmd,trans,null,cmdType,cmdText,commandParameters);
int val=cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
ExecuteReader方法
/// <summary>
/// Execute a SqlCommand that returns a resultset against the database specified in the connection string
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">a valid connection string for a SqlConnection</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>A SqlDataReader containing the results</returns>
-------------------------------------------------------------------------------------------------------------------------------------------------
public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {
Command cmd = new SqlCommand();
Connection conn = new SqlConnection(connectionString);
// we use a try/catch here because if the method throws an exception we want to
// close the connection throw code, because no datareader will exist, hence the
// commandBehaviour.CloseConnection will not work
try {
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return rdr;
}
catch {
conn.Close();
throw;
}
}
PrepareCommand方法
格式化命令
/// <summary>
/// Prepare a command for execution
/// </summary>
/// <param name="cmd">SqlCommand object</param>
/// <param name="conn">SqlConnection object</param>
/// <param name="trans">SqlTransaction object</param>
/// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
/// <param name="cmdText">Command text, e.g. Select * from Products</param>
/// <param name="cmdParms">SqlParameters to use in the command</param>
-------------------------------------------------------------------------------------------------------------------------------------------------
private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms) {
if (conn.State != ConnectionState.Open)
conn.Open();
cmd.Connection = conn;
cmd.CommandText = cmdText;
if (trans != null)
cmd.Transaction = trans;
cmd.CommandType = cmdType;
if (cmdParms != null) {
foreach (SqlParameter parm in cmdParms)
cmd.Parameters.Add(parm);
}
}
