列メタデータの取得
次のコードは、CompositeDataReaderを使用して列のメタデータにアクセスする方法を示しています。
GetSchemaTableを呼び出して、DataTableオブジェクトを取得できます。いくつかの行が含まれ、列のメタデータとともに存在するすべての行を返します。メタデータには次のものが含まれます。
ColumnName, ColumnOrdinal, ColumnSize, NumericPrecision, NumericScale, DataType, ProviderType, IsLong, AllowDBNull, IsReadOnly, IsRowVersion, IsUnique, IsKey, IsAutoIncrement, BaseSchemaName, BaseCatalogName, BaseTableName, and BaseColumnName.
列のメタデータを取得するには
1. 次のコードを使用して、行とメタデータを名前で取得します。 BaseSchemaName、BaseCatalogName、およびBaseTableNameは常に存在します。
public void TestReaderMetadata()
{
CompositeConnection conn = GetConnection();
Try
{
CompositeCommand cmd = conn.CreateCommand();
cmd.CommandText = "SELECT * FROM PRODUCTS WHERE ProductID=1111";
CompositeDataReader reader = cmd.ExecuteReader();
DataTable dt = reader.GetSchemaTable();
INT ROWS = dt.Rows.Count;
IF (rows > 0)
{
foreach (DataRow row in dt.Rows)
{
String ColumnName = (String)row["ColumnName"];
int ColumnOrdinal = (int)row["ColumnOrdinal"];
int ColumnSize = (int)row["ColumnSize"];
int NumericPrecision = (int)row["NumericPrecision"];
int NumericScale = (int)row["NumericScale"];
Type DataType = (Type)row["DataType"];
int ProviderType = (int)row["ProviderType"];
bool IsLong = (bool)row["IsLong"];
bool AllowDBNull = (bool)row["AllowDBNull"];
bool IsReadOnly = (bool)row["IsReadOnly"];
bool IsRowVersion = (bool)row["IsRowVersion"];
bool IsUnique = (bool)row["IsUnique"];
bool IsKey = (bool)row["IsKey"];
bool IsAutoIncrement = (bool)row["IsAutoIncrement"];
String BaseSchemaName = (String)row["BaseSchemaName"];
String BaseCatalogName = (String)row["BaseCatalogName"];
String BaseTableName = (String)row["BaseTableName"];
String BaseColumnName = (String)row["BaseColumnName"];
Console.WriteLine("Column properties:");
Console.WriteLine("ColumnName:" + ColumnName+
",ColumnOrdinal:" + ColumnOrdinal+
",ColumnSize:" + ColumnSize+
",NumericPrecision:" + NumericPrecision+
",NumericScale:" + NumericScale+
",DataType:" + DataType+
",ProviderType:" + ProviderType+
",IsLong:" + IsLong+
",AllowDBNull:" + AllowDBNull+
",IsReadOnly:" + IsReadOnly+
",IsRowVersion:" + IsRowVersion+
",IsUnique:" + IsUnique+
",IsKey:" + IsKey+
",IsAutoIncrement:" + IsAutoIncrement+
",BaseSchemaName:" + BaseSchemaName+
",BaseCatalogName:" + BaseCatalogName+
",BaseTableName:" + BaseTableName+
",BaseColumnName:" + BaseColumnName+"."
);
}
}
reader.Close();
}
catch (Exception ex)
{
Assert.Fail(ex.Message);
}
}