Question

sqldatareader GetValues怎么用

Answer 1

下列范例示范如何使用适当大小的阵列，从提供之 SqlDataReader 中目前的资料列读取所有值。此外，此范例示范了使用固定大小之阵列的情形，而该阵列可能小於或大於可用资料行的数目。
privatestaticvoid TestGetValues(SqlDataReader reader)
{
// Given a SqlDataReader, use the GetValues
// method to retrieve a full row of data.
// Test the GetValues method, passing in an array large
// enough for all the columns.
Object[] values = new Object[reader.FieldCount];
int fieldCount = reader.GetValues(values);

Console.WriteLine("reader.GetValues retrieved {0} columns.",
fieldCount);
for (int i = 0; i < fieldCount; i++)
Console.WriteLine(values[i]);

Console.WriteLine();

// Now repeat, using an array that may contain a different
// number of columns than the original data. This should work correctly,
// whether the size of the array is larger or smaller than
// the number of columns.

// Attempt to retrieve three columns of data.
values = new Object[3];
fieldCount = reader.GetValues(values);
Console.WriteLine("reader.GetValues retrieved {0} columns.",
fieldCount);
for (int i = 0; i < fieldCount; i++)
Console.WriteLine(values[i]);
}

Answer 2

private static void TestGetValues(SqlDataReader reader)
{
// Given a SqlDataReader, use the GetValues
// method to retrieve a full row of data.
// Test the GetValues method, passing in an array large
// enough for all the columns.
Object[] values = new Object[reader.FieldCount];
int fieldCount = reader.GetValues(values);

Console.WriteLine("reader.GetValues retrieved {0} columns.",
fieldCount);
for (int i = 0; i < fieldCount; i++)
Console.WriteLine(values[i]);

Console.WriteLine();

// Now repeat, using an array that may contain a different
// number of columns than the original data. This should work correctly,
// whether the size of the array is larger or smaller than
// the number of columns.

// Attempt to retrieve three columns of data.
values = new Object[3];
fieldCount = reader.GetValues(values);
Console.WriteLine("reader.GetValues retrieved {0} columns.",
fieldCount);
for (int i = 0; i < fieldCount; i++)
Console.WriteLine(values[i]);
}

Answer 3

参数 :要复制的Object 数组
返回值:数组中 Object 的实例的数目。
使用时两点要注意:1,使用完后,必须调用Close 方法. 2,数组中的值 和 SQL 语句中 SELECT 的列顺序一样,比如 SELECT A,B,C FROM TABLE 那么返回值的数据 objs[0] 就是A 的值,objs[1] 就是B 的值,以此类推.
SqlCommand cmd = new SqlCommand("SELECT A,B,C FROM TABLE",cnn);
SqlDataReader reader = cmd.ExecuteReader();
if (!reader.HasRow())
{
reader.Close();
return null;
}
while (reader.Read())
{
Object[] objs = new Object[reader.FieldCount];
reader.GetValues(objs);
//下面应该是你处理数据的代码
}

reader.close();