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使用Command执行存储过程 (转)

原创 数据库开发技术 作者:amyz 时间:2007-08-16 19:25:03 0 删除 编辑
使用Command执行存储过程 (转)[@more@]

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.NET framework Developer's Guide

使用Command执行存储过程

 

在数据驱动的应用程序中,存储过程可以提供很多优点。使用存储过程可以将数据库操作封装到一条简单的命令中,可以优化效能,可以增强安全性。只需要按照sql语法在存储过程名后面跟带参数就可以调用该存储过程。使用ado.net中Command对象的Parameters属性你还可以明确的定义和使用output参数和return值。

调用存储过程时,要设置Command对象的CommandType属性为StoreProcedure。一旦设定了CommandType属性为StoreProcedure,你就可以使用Parameters集合来定义参数,就像下面的例子。

注意 使用OdbcCommand调用存储过程时要求提供完整的ODBC CALL语法。

SqlClient

[Visual Basic]


Dim nwindConn As SqlConnection = New SqlConnection("Data source=localhost;Integrated Security=SSPI;" & _


   "Initial Catalog=northwind")


 


Dim salesCMD As SqlCommand = New SqlCommand("SalesByCategory", nwindConn)


salesCMD.CommandType = CommandType.StoredProcedure


 


Dim myPaRM As SqlParameter = salesCMD.Parameters.Add("@CategoryName", SqlDbType.NVarChar, 15)


myParm.Value = "Beverages"


 


nwindConn.Open()


 


Dim myReader As SqlDataReader = salesCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", myReader.GetName(0), myReader.GetName(1))


 


Do While myReader.Read()


  Console.WriteLine("{0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1))


Loop


 


myReader.Close()


nwindConn.Close()


[C#]


SqlConnection nwindConn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=northwind");


 


SqlCommand salesCMD = new SqlCommand("SalesByCategory", nwindConn);


salesCMD.CommandType = CommandType.StoredProcedure;


 


SqlParameter myParm = salesCMD.Parameters.Add("@CategoryName", SqlDbType.NVarChar, 15);


myParm.Value = "Beverages";


 


nwindConn.Open();


 


SqlDataReader myReader = salesCMD.ExecuteReader();


 


Console.WriteLine("{0}, {1}", myReader.GetName(0), myReader.GetName(1));


 


while (myReader.Read())


{


  Console.WriteLine("{0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1));


}


 


myReader.Close();


nwindConn.Close();


OleDb

[Visual Basic]


Dim nwindConn As OleDbConnection = New OleDbConnection("Provider=SQLOLEDB;Data Source=localhost;Integrated Security=SSPI;" & _


  "Initial Catalog=northwind")


 


Dim salesCMD As OleDbCommand = New OleDbCommand("SalesByCategory", nwindConn)


salesCMD.CommandType = CommandType.StoredProcedure


 


Dim myParm As OleDbParameter = salesCMD.Parameters.Add("@CategoryName", OleDbType.VarChar, 15)


myParm.Value = "Beverages"


 


nwindConn.Open()


 


Dim myReader As OleDbDataReader = salesCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", myReader.GetName(0), myReader.GetName(1))


 


Do While myReader.Read()


  Console.WriteLine("{0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1))


Loop


 


myReader.Close()


nwindConn.Close()


[C#]


OleDbConnection nwindConn = new OleDbConnection("Provider=SQLOLEDB;Data Source=localhost;Integrated Security=SSPI;" +


  "Initial Catalog=northwind");


 


OleDbCommand salesCMD = new OleDbCommand("SalesByCategory", nwindConn);


salesCMD.CommandType = CommandType.StoredProcedure;


 


OleDbParameter myParm = salesCMD.Parameters.Add("@CategoryName", OleDbType.VarChar, 15);


myParm.Value = "Beverages";


 


nwindConn.Open();


 


OleDbDataReader myReader = salesCMD.ExecuteReader();


 


Console.WriteLine(" {0}, {1}", myReader.GetName(0), myReader.GetName(1));


 


while (myReader.Read())


{


  Console.WriteLine(" {0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1));


}


 


myReader.Close();


nwindConn.Close();


Odbc

[Visual Basic]


Dim nwindConn As OdbcConnection = New OdbcConnection("driver={SQL SERVER};Server=localhost;Trusted_Connection=yes;" & _


  "Database=northwind")


nwindConn.Open()


 


Dim salesCMD As OdbcCommand = New OdbcCommand("{ CALL SalesByCategory(?) }", nwindConn)


salesCMD.CommandType = CommandType.StoredProcedure


 


Dim myParm As OdbcParameter = salesCMD.Parameters.Add("@CategoryName", OdbcType.VarChar, 15)


myParm.Value = "Beverages"


 


Dim myReader As OdbcDataReader = salesCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", myReader.GetName(0), myReader.GetName(1))


 


Do While myReader.Read()


  Console.WriteLine("{0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1))


Loop


 


myReader.Close()


nwindConn.Close()


[C#]


OdbcConnection nwindConn = new OdbcConnection("Driver={SQL Server};Server=localhost;Trusted_Connection=yes;" +


  "Database=northwind");


nwindConn.Open();


 


OdbcCommand salesCMD = new OdbcCommand("{ CALL SalesByCategory(?) }", nwindConn);


salesCMD.CommandType = CommandType.StoredProcedure;


 


OdbcParameter myParm = salesCMD.Parameters.Add("@CategoryName", OdbcType.VarChar, 15);


myParm.Value = "Beverages";


 


OdbcDataReader myReader = salesCMD.ExecuteReader();


 


Console.WriteLine(" {0}, {1}", myReader.GetName(0), myReader.GetName(1));


 


while (myReader.Read())


{


  Console.WriteLine(" {0}, ${1}", myReader.GetString(0), myReader.GetDecimal(1));


}


 


myReader.Close();


nwindConn.Close();


一个Parameter对象可以使用Parameter构造器创建,也可以通过调用Command对象的Parameters集合的Add方法创建。Parameters.Add方法的输入参数可以和构造器相同,也可以使用一个存在的Parameter对象。用System.DBNull.Value设置Parameter的值为空。

如果要设置Parameter为非一般的输入参数时,必须设置ParameterDirection属性为InputOutput,Output,或者ReturnValue。下面的例子演示了创建Input, Output, 和 ReturnValue参数的差别。

SqlClient

[Visual Basic]


Dim sampleCMD As SqlCommand = New SqlCommand("SampleProc", nwindConn)


sampleCMD.CommandType = CommandType.StoredProcedure


 


Dim sampParm As SqlParameter = sampleCMD.Parameters.Add("RETURN_VALUE", SqlDbType.Int)


sampParm.Direction = ParameterDirection.ReturnValue


 


sampParm = sampleCMD.Parameters.Add("@InputParm", SqlDbType.NVarChar, 12)


sampParm.Value = "Sample Value"


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", SqlDbType.NVarChar, 28)


sampParm.Direction = ParameterDirection.Output


 


nwindConn.Open()


 


Dim sampReader As SqlDataReader = sampleCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1))


 


Do While sampReader.Read()


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1))


Loop


 


sampReader.Close()


nwindConn.Close()


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters("@OutputParm").Value)


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters("RETURN_VALUE").Value)


[C#]


SqlCommand sampleCMD = new SqlCommand("SampleProc", nwindConn);


sampleCMD.CommandType = CommandType.StoredProcedure;


 


SqlParameter sampParm = sampleCMD.Parameters.Add("RETURN_VALUE", SqlDbType.Int);


sampParm.Direction = ParameterDirection.ReturnValue;


 


sampParm = sampleCMD.Parameters.Add("@InputParm", SqlDbType.NVarChar, 12);


sampParm.Value = "Sample Value";


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", SqlDbType.NVarChar, 28);


sampParm.Direction = ParameterDirection.Output;


 


nwindConn.Open();


 


SqlDataReader sampReader = sampleCMD.ExecuteReader();


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1));


 


while (sampReader.Read())


{


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1));


}


 


sampReader.Close();


nwindConn.Close();


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters["@OutputParm"].Value);


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters["RETURN_VALUE"].Value);


OleDb

[Visual Basic]


Dim sampleCMD As OleDbCommand = New OleDbCommand("SampleProc", nwindConn)


sampleCMD.CommandType = CommandType.StoredProcedure


 


Dim sampParm As OleDbParameter = sampleCMD.Parameters.Add("RETURN_VALUE", OleDbType.Integer)


sampParm.Direction = ParameterDirection.ReturnValue


 


sampParm = sampleCMD.Parameters.Add("@InputParm", OleDbType.VarChar, 12)


sampParm.Value = "Sample Value"


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", OleDbType.VarChar, 28)


sampParm.Direction = ParameterDirection.Output


 


nwindConn.Open()


 


Dim sampReader As OleDbDataReader = sampleCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1))


 


Do While sampReader.Read()


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1))


Loop


 


sampReader.Close()


nwindConn.Close()


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters("@OutputParm").Value)


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters("RETURN_VALUE").Value)


[C#]


OleDbCommand sampleCMD = new OleDbCommand("SampleProc", nwindConn);


sampleCMD.CommandType = CommandType.StoredProcedure;


 


OleDbParameter sampParm = sampleCMD.Parameters.Add("RETURN_VALUE", OleDbType.Integer);


sampParm.Direction = ParameterDirection.ReturnValue;


 


sampParm = sampleCMD.Parameters.Add("@InputParm", OleDbType.VarChar, 12);


sampParm.Value = "Sample Value";


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", OleDbType.VarChar, 28);


sampParm.Direction = ParameterDirection.Output;


 


nwindConn.Open();


 


OleDbDataReader sampReader = sampleCMD.ExecuteReader();


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1));


 


while (sampReader.Read())


{


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1));


}


 


sampReader.Close();


nwindConn.Close();


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters["@OutputParm"].Value);


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters["RETURN_VALUE"].Value);


Odbc

[Visual Basic]


Dim sampleCMD As OdbcCommand = New OdbcCommand("{ ? = CALL SampleProc(?, ?) }", nwindConn)


sampleCMD.CommandType = CommandType.StoredProcedure


 


Dim sampParm As OdbcParameter = sampleCMD.Parameters.Add("RETURN_VALUE", OdbcType.Int)


sampParm.Direction = ParameterDirection.ReturnValue


 


sampParm = sampleCMD.Parameters.Add("@InputParm", OdbcType.VarChar, 12)


sampParm.Value = "Sample Value"


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", OdbcType.VarChar, 28)


sampParm.Direction = ParameterDirection.Output


 


nwindConn.Open()


 


Dim sampReader As OdbcDataReader = sampleCMD.ExecuteReader()


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1))


 


Do While sampReader.Read()


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1))


Loop


 


sampReader.Close()


nwindConn.Close()


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters("@OutputParm").Value)


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters("RETURN_VALUE").Value)


[C#]


OdbcCommand sampleCMD = new OdbcCommand("{ ? = CALL SampleProc(?, ?) }", nwindConn);


sampleCMD.CommandType = CommandType.StoredProcedure;


 


OdbcParameter sampParm = sampleCMD.Parameters.Add("RETURN_VALUE", OdbcType.Int);


sampParm.Direction = ParameterDirection.ReturnValue;


 


sampParm = sampleCMD.Parameters.Add("@InputParm", OdbcType.VarChar, 12);


sampParm.Value = "Sample Value";


 


sampParm = sampleCMD.Parameters.Add("@OutputParm", OdbcType.VarChar, 28);


sampParm.Direction = ParameterDirection.Output;


 


nwindConn.Open();


 


OdbcDataReader sampReader = sampleCMD.ExecuteReader();


 


Console.WriteLine("{0}, {1}", sampReader.GetName(0), sampReader.GetName(1));


 


while (sampReader.Read())


{


  Console.WriteLine("{0}, {1}", sampReader.GetInt32(0), sampReader.GetString(1));


}


 


sampReader.Close();


nwindConn.Close();


 


Console.WriteLine(" @OutputParm: {0}", sampleCMD.Parameters["@OutputParm"].Value);


Console.WriteLine("RETURN_VALUE: {0}", sampleCMD.Parameters["RETURN_VALUE"].Value);


在SqlCommand中使用参数

在SqlCommand中使用参数时,参数的名字必须和存储过程中相应参数的名字匹配。SQL SERVER的.NET Framework Data Provider将存储过程中的参数视为命名参数并且搜索与之匹配的参数标记。

SQL SERVER的.NET Framework Data Provider不支持使用问号标记(?)作为占位符来向SQL语句或者存储过程传递参数。既然如此,你必须命名参数,就下面一样:

select * FROM Customers WHERE CustomerID = @CustomerID


在OleDbCommand 和OdbcCommand中使用参数

在OleDbCommand或者OdbcCommand中使用参数时,参数添加到Parameters集合中的顺序必须和存储过程中参数定义的顺序匹配。OLE DB和ODBC的.NET Framework数据供应程序将存储过程的参数视为占位符,按照顺序来给参数赋值。另外,返回参数必须是第一个被加入到Parameters集合中的参数。

OLE DB和ODBC的.NET Framework数据供应程序不提供使用命名参数来向SQL语句或存储过程传递参数。为此,你必须使用问号(?)占位符,就像下面一样:

SELECT * FROM Customers WHERE CustomerID = ?


因此,向 Parameters 集合添加 Parameter 对象的顺序必须直接对应于该参数的问号占位符的位置。

导出参数信息

参数也可以使用 CommandBuilder 类从存储过程导出。SqlCommandBuilder 和 OleDbCommandBuilder 类都提供了静态方法 DeriveParameters,该静态方法将自动使用存储过程中的参数信息填充 Command 对象的 Parameters 集合。请注意,DeriveParameters 将改写 Command 的任何现有参数信息。

导出参数信息时需要经历一个到数据源的附加行程,以获取参数信息。如果参数信息在设计时是已知的,则可以通过显式设置参数来提高应用程序的性能。

以下代码示例显示如何使用 CommandBuilder.DeriveParameters 来填充 Command 对象的 Parameters 集合。

[Visual Basic]


Dim nwindConn As SqlConnection = New SqlConnection("Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI;")


Dim salesCMD As SqlCommand = New SqlCommand("Sales By Year", nwindConn)


salesCMD.CommandType = CommandType.StoredProcedure


 


nwindConn.Open()


SqlCommandBuilder.DeriveParameters(salesCMD)


nwindConn.Close()


[C#]


SqlConnection nwindConn = new SqlConnection("Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI;");


SqlCommand salesCMD = new SqlCommand("Sales By Year", nwindConn);


salesCMD.CommandType = CommandType.StoredProcedure;


 


nwindConn.Open();


SqlCommandBuilder.DeriveParameters(salesCMD);


nwindConn.Close();


 


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