Oracle Data Provider for .NET

ODP.NET types represent Oracle native types as a structure or as a class. For example, an OracleDecimal holds up to 38 precisions while a .NET Decimal holds only up to 28 precisions.

Table 3.2 lists all the Oracle native types supported by ODP.NET and their corresponding ODP.NET type. The third column lists the .NET Framework datatype that corresponds to the Value property of each ODP.NET Type.

Table 3-2 Oracle Native Types Supported by ODP.NET  

Oracle Native Type	ODP.NET Type	.NET Framework  Datatypes
BFILE	OracleBFile class	System.Byte[]
BLOB	OracleBlob class	System.Byte[]
CHAR	OracleString structure	System.String
CLOB	OracleClob class	System.String
DATE	OracleDate structure	System.DateTime
INTERVAL DAY TO SECOND	OracleIntervalDS structure	System.TimeSpan
INTERVAL YEAR TO MONTH	OracleIntervalYM structure	System.Int64
LONG	OracleString structure	System.String
LONG RAW	OracleBinary structure	System.Byte[]
NCLOB	OracleClob class	System.String
NCHAR	OracleString structure	System.String
NUMBER	OracleDecimal structure	System.Decimal
NVARCHAR2	OracleString structure	System.String
RAW	OracleBinary structure	System.Byte[]
REF CURSOR	OracleRefCursor class	Not Applicable
TIMESTAMP	OracleTimeStamp structure	System.DateTime
TIMESTAMP WITH LOCAL TIME ZONE	OracleTimeStampLTZ structure	System.DateTime
TIMESTAMP WITH TIME ZONE	OracleTimeStampTZ structure	System.DateTime
UROWID	OracleString structure	System.String
VARCHAR2	OracleString structure	System.String
XMLType	OracleXmlType class	System.String

Obtaining Data From an OracleDataReader

The ExecuteReader method of the OracleCommand object returns an OracleDataReader object, which is a read-only, forward-only result set.

Typed OracleDataReader Accessors
The OracleDataReader provides two types of typed accessors:

.NET Type Accessors
Table 3.3 lists all the Oracle native database types that ODP.NET supports and the corresponding .NET Type that best represents the Oracle native type. The third column indicates the valid typed accessor that can be invoked for an Oracle native type to be obtained as a .NET type. If an invalid typed accessor is used for a column, an InvalidCastException is thrown. Oracle native datatypes depend on the version of the database; therefore, some datatypes are not available in earlier versions of Oracle. 

Table 3-3 .NET Type Accessors  

Oracle Native Datatype	.NET Type	Typed Accessor
BFILE	System.Byte[ ]	GetBytes
BLOB	System.Byte[ ]	GetBytes
CHAR	System.String	GetString GetChars
CLOB	System.String	GetString GetChars
DATE	System.DateTime	GetDateTime
INTERVAL (DS)	System.Interval	GetTimeSpan
INTERVAL (YM)	System.Interval	GetTimeSpan
LONG	System.String	GetString GetChars
LONG RAW	System.Byte[ ]	GetBytes
NCHAR	System.String	GetString GetChars
NCLOB	System.String	GetString GetChars
NUMBER	System.Decimal	GetDecimal
NVARCHAR2	System.String	GetString GetChars
RAW	System.Byte[ ]	GetBytes
ROWID	System.String	GetString GetChars
TIMESTAMP	System.TimeStamp	GetTimeStamp
TIMESTAMP WITH LOCAL TIME ZONE	System.TimeStamp	GetTimeStamp
TIMESTAMP WITH TIME ZONE	System.TimeStamp	GetTimeStamp
UROWID	System.String	GetString GetChars
VARCHAR2	System.String	GetString GetChars
XMLType	System.String System.Xml.XmlReader	GetString GetXmlReader

ODP.NET Type Accessors

ODP.NET exposes provider-specific types that natively represent the datatypes in Oracle. In some cases, these ODP.NET types provide better performance and functionality that is not available to the corresponding .NET types. The ODP.NET types can be obtained from the OracleDataReader by calling their respective typed accessor.

Table 3.4 lists the valid type accessors that ODP.NET uses to obtain ODP.NET Types for an Oracle native type.

Table 3-4 ODP.NET Type Accessors  

Oracle Native Database Type	ODP.NET Type	Typed Accessor
BFILE	OracleBFile	GetOracleBFile
BLOB	OracleBlob OracleBlob OracleBinary	GetOracleBlob GetOracleBlobForUpdate GetOracleBinary
CHAR	OracleString	GetOracleString
CLOB	OracleClob OracleClob OracleString	GetOracleClob GetOracleClobForUpdate GetOracleString
DATE	OracleDate	GetOracleDate
INTERVAL (DS)	OracleIntervalDS	GetOracleIntervalDS
INTERVAL (YM)	OracleIntervalYM	GetOracleIntervalYM
LONG	OracleString	GetOracleString
LONG RAW	OracleBinary	GetOracleBinary
NCHAR	OracleString	GetOracleString
NCLOB	OracleString	GetOracleString
NUMBER	OracleDecimal	GetOracleDecimal
NVARCHAR2	OracleString	GetOracleString
RAW	OracleBinary	GetOracleBinary
ROWID	OracleString	GetOracleString
TIMESTAMP	OracleTimeStamp	GetOracleTimeStamp
TIMESTAMP WITH LOCAL TIME ZONE	OracleTimeStampLTZ	GetOracleTimeStampLTZ
TIMESTAMP WITH TIME ZONE	OracleTimeStampTZ	GetOracleTimeStampTZ
UROWID	OracleString	GetOracleString
VARCHAR2	OracleString	GetOracleString
XMLType	OracleString OracleXmlType	GetOracleString  GetOracleXmlType

Obtaining LONG and LONG RAW Data

When an OracleDataReader is created containing a LONG or LONG RAW column type, OracleDataReader determines whether this column data needs to be fetched immediately or not, by checking the value of the InitialLONGFetchSize property of the OracleCommand that created the OracleDataReader.

By default, InitialLONGFetchSize is set to 0. If the InitialLONGFetchSize property value of the OracleCommand is left as 0, the entire LONG or LONG RAW data retrieval is deferred until that data is explicitly requested by the application. If the InitialLONGFetchSize property is set to a nonzero value, the LONG or LONG RAW data is immediately fetched up to the number of characters or bytes that the InitialLONGFetchSize property specifies.

ODP.NET does not support CommandBehavior.SequentialAccess. Therefore, LONG and LONG RAW data can be fetched in a random fashion. 

Obtain data beyond InitialLONGFetchSize bytes or characters, one of the following must be in the select list:

• primary key 
• ROWID 
• unique columns - (defined as a set of columns on which a unique constraint has been defined or a unique index has been created, where at least one of the columns in the set has a NOT NULL constraint defined on it).

The requested data is fetched from the database when the appropriate typed accessor method (GetOracleString or GetString for LONG or GetOracleBinary or GetBytes for LONG RAW) is called on the OracleDataReader object.

In order to fetch the data in a non-defer mode or when the columns in the select list do not have a primary key column, a ROWID, or unique columns, set the size of the InitialLONGFetchSize property on the OracleCommand object to equal or greater than the amount of bytes or characters needed to be retrieved. 

 

 

OracleDbType Enumeration Type

OracleDbType enumerated values are used to explicitly specify the OracleDbType of an OracleParameter.

Table 3.5 lists all the OracleDbType enumeration values with a description of each enumerated value.

Table 3-5 OracleDbType Enumeration Values  

Member Name	Description
BFile	Oracle BFILE type
Blob	Oracle BLOB type
Byte	byte type
Char	Oracle CHAR type
Clob	Oracle CLOB type
Date	Oracle DATE type
Decimal	Oracle NUMBER type
Double	8-byte FLOAT type
Int16	2-byte INTEGER type
Int32	4-byte INTEGER type
Int64	8-byte INTEGER type
IntervalDS	Oracle INTERVAL DAY TO SECOND type
IntervalYM	Oracle INTERVAL YEAR TO MONTH type
Long	Oracle LONG type
LongRaw	Oracle LONG RAW type
NChar	Oracle NCHAR type
NClob	Oracle NCLOB type
NVarchar2	Oracle NVARCHAR2 type
Raw	Oracle RAW type
RefCursor	Oracle REF CURSOR type
Single	4-byte FLOAT type
TimeStamp	Oracle TIMESTAMP type
TimeStampLTZ	Oracle TIMESTAMP WITH LOCAL TIME ZONE type
TimeStampTZ	Oracle TIMESTAMP WITH TIME ZONE type
Varchar2	Oracle VARCHAR2 type
XmlType	Oracle XMLType type

Inference of DbType, OracleDbType, and .NET Types

This section explains the inference from the System.Data.DbType, OracleDbType, and Value properties in the OracleParameter class.

In the OracleParameter class, DbType, OracleDbType, and Value properties are linked. Specifying the value of any of these properties infers the value of one or more of the other properties.

Inference of DbType from OracleDbType

In the OracleParameter class, specifying the value of OracleDbType infers the value of DbType as shown in Table 3.6.

Table 3-6 Inference of System.Data.DbType from OracleDbType

OracleDbType	System.Data.DbType
BFile	Object
Blob	Object
Byte	Byte
Char	StringFixedLength
Clob	Object
Date	Date
Decimal	Decimal
Double	Double
Int16	Int16
Int32	Int32
Int64	Int64
IntervalDS	TimeSpan
IntervalYM	Int64
Long	String
LongRaw	Binary
NChar	StringFixedLength
NClob	Object
NVarchar2	String
Raw	Binary
RefCursor	Object
Single	Single
TimeStamp	DateTime
TimeStampLTZ	DateTime
TimeStampTZ	DateTime
Varchar2	String
XmlType	String

Inference of OracleDbType from DbType

In the OracleParameter class, specifying the value of DbType infers the value of OracleDbType as shown inTable 3.7.

Table 3-7 Inference of OracleDbType from DbType  

System.Data.DbType	OracleDbType
Binary	Raw
Boolean	Not Supported
Byte	Byte
Currency	Not Supported
Date	Date
DateTime	TimeStamp
Decimal	Decimal
Double	Double
Guid	Not Supported
Int16	Int16
Int32	Int32
Int64	Int64
Object	Not Supported
Sbyte	Not Supported
Single	Single
String	Varchar2
StringFixedLength	Char
Time	TimeStamp
UInt16	Not Supported
UInt32	Not Supported
Uint64	Not Supported
VarNumeric	Not Supported

Inference of DbType and OracleDbType from Value

In the OracleParameter class, Value is an object type which can be of any .NET Framework datatype or ODP.NET type. If the OracleDbType and DbType in the OracleParameter object are not specified, OracleDbType is inferred from the type of the Value property.

Table 3.8 shows the inference of DbType and OracleDbType from Value when the type of Value is one of the .NET Framework datatypes.

Table 3-8 Inference of DbType and OracleDbType from Value (.NET Datatypes)  

Value (.NET Datatypes)	System.Data.DbType	OracleDbType
Byte	Byte	Byte
Byte[]	Binary	Raw
Char / Char []	String	Varchar2
DateTime	DateTime	TimeStamp
Decimal	Decimal	Decimal
Double	Double	Double
Float	Single	Single
Int16	Int16	Int16
Int32	Int32	Int32
Int64	Int64	Int64
Single	Single	Single
String	String	Varchar2
TimeSpan	TimeSpan	IntervalDS

Table 3.9 shows the inference of DbType and OracleDbType from Value when type of Value is one of Oracle.DataAccess.Types.

Table 3-9 Inference of DbType and OracleDbType from Value (ODP.NET Types)  

Value (Oracle.DataAccess.Types)	System.Data.DbType	OracleDbType
OracleBFile	Object	BFile
OracleBinary	Binary	Raw
OracleBlob	Object	Blob
OracleClob	Object	Clob
OracleDate	Date	Date
OracleDecimal	Decimal	Decimal
OracleIntervalDS	Object	IntervalDS
OracleIntervalYM	Int64	IntervalYM
OracleRefCursor	Object	RefCursor
OracleString	String	Varchar2
OracleTimeStamp	DateTime	TimeStamp
OracleTimeStampLTZ	DateTime	TimeStampLTZ
OracleTimeStampTZ	DateTime	TimeStampTZ
OracleXmlType	String	XmlType

PL/SQL Associative Array

ODP.NET supports PL/SQL Associative Array (formerly known as PL/SQL Index-By Tables) binding.

An application can bind an OracleParameter, as a PL/SQL Associative Array, to a PL/SQL stored procedure. The following OracleParameter properties are used for this feature.

• CollectionType
  This property must be set to OracleCollectionType.PLSQLAssociativeArray to bind a PL/SQL Associative Array.
  
  
• ArrayBindSize
  This property is ignored for the fixed-length element types (such as Int32).
  For variable-length element types (such as Varchar2), each element in the ArrayBindSize property specifies the size of the corresponding element in the Value property. For Output parameters, InputOutput parameters, and return values, this property must be set for variable-length variables.
• ArrayBindStatus
  This property specifies the execution status of each element in the OracleParameter.Value property.
  
• Size
  This property specifies the maximum number of elements to be bound in the PL/SQL Associative Array.
  
• Value
  This property must either be set to an array of values or null or DBNull.Value. 

 

Code Example

This example binds three OracleParameter objects as PL/SQL Associative Arrays: Param1 as an In parameter, Param2 as an InputOutput parameter, and Param3 as an Output parameter.

PL/SQL Package: My Pack
CREATE PACKAGE MYPACK AS
TYPE AssocArrayVarchar2_t is table of VARCHAR(20) index by BINARY_INTEGER;
PROCEDURE TestVarchar2(
Param1 IN AssocArrayVarchar2_t,
Param2 IN OUT AssocArrayVarchar2_t,
Param3 OUT AssocArrayVarchar2_t);
END MYPACK;

PL/SQL Package Body: My Pack
CREATE PACKAGE BODY MYPACK AS
PROCEDURE TestVarchar2(
Param1 IN AssocArrayVarchar2_t,
Param2 IN OUT AssocArrayVarchar2_t,
Param3 OUT AssocArrayVarchar2_t)
IS
i integer;
BEGIN
-- copy a few elements from y to z
Param3(1) := Param2(1);
Param3(2) := NULL;
Param3(3) := Param2(3);

-- copy all elements from x to y
Param2(1) := Param1(1);
Param2(2) := Param1(2);
Param2(3) := Param1(3);

FOR i IN 1..3 LOOP
insert into T1 values(i, Param2(i));
END LOOP;

FOR i IN 1..3 LOOP
select COL2 into Param2(i) from T2 where COL1 = i;
END LOOP;
END TestVarchar2;
END MYPACK;

ODP.NET Example

public void BindAssocArray()
{
...
OracleCommand cmd = new OracleCommand(
"begin MyPack.TestVarchar2(:1, :2, :3); end;", con);
OracleParameter Param1 = cmd.Parameters.Add(...);
OracleParameter Param2 = cmd.Parameters.Add(...);
OracleParameter Param3 = cmd.Parameters.Add(...);
Param1.Direction = ParameterDirection.Input;
Param2.Direction = ParameterDirection.InputOutput;
Param3.Direction = ParameterDirection.Output;
// Specify that we are binding PL/SQL Associative Array
Param1.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
Param2.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
Param3.CollectionType = OracleCollectionType.PLSQLAssociativeArray;
// Setup the values for PL/SQL Associative Array
Param1.Value = new string[3]{"First Element",
"Second Element ",
"Third Element ",
Param2.Value = new string[3]{"First Element",
"Second Element ",
"Third Element ",
Param3.Value = null;
// Specify the maximum number of elements in the PL/SQL Associative Array
Param1.Size = 3;
Param2.Size = 3;
Param3.Size = 3;
// Setup the ArrayBindSize for Param1
Param1.ArrayBindSize = new int[3]{13, 14, 13};
// Setup the ArrayBindStatus for Param1
Param1.ArrayBindStatus = new OracleParameterStatus[3]{
OracleParameterStatus.Success,
OracleParameterStatus.Success,
OracleParameterStatus.Success};
// Setup the ArrayBindSize for Param2
Param2.ArrayBindSize = new int[3]{20, 20, 20};
// Setup the ArrayBindSize for Param3
Param3.ArrayBindSize = new int[3]{20, 20, 20};
// execute the cmd
cmd.ExecuteNonQuery();
//print out the parameter's values
......
}

Array Binding

The array bind feature enables applications to bind arrays of a type using the OracleParameter class. Using the array bind feature, an application can insert multiple rows into a table in a single database round-trip. The following code example inserts three rows into the Dept table with a single database round-trip. The OracleCommand ArrayBindCount property defines the number of elements of the array to use when executing the statement.

// C#
...
// Create an array of values that need to be inserted
int[] myArrayDeptNo = new int[3]{10, 20, 30};
// Set the command text on an OracleCommand object
cmd.CommandText = "insert into dept(deptno) values (:deptno)";
// Set the ArrayBindCount to indicate the number of values
cmd.ArrayBindCount = 3;
// Create a parameter for the array operations
OracleParameter prm = new OracleParameter("deptno", OracleDbType.Int32);
prm.Direction = ParameterDirection.Input;
prm.Value = myArrayDeptNo;
// Add the parameter to the parameter collection
cmd.Parameters.Add(prm);
// Execute the command
cmd.ExecuteNonQuery();

OracleParameter Array Bind Properties

The OracleParameter object provides two properties for granular control when using the array bind feature:

• ArrayBindSize Property
  The ArrayBindSize property is an array of integers specifying the maximum size for each corresponding value in an array. The ArrayBindSize property is similar to the Size property of an OracleParameter except ArrayBindSize specifies the size for each value in an array.
  Before the execution, the application must populate ArrayBindSize; after the execution, ODP.NET populates the ArrayBindSize.
  ArrayBindSize is used only for parameter types that have variable length such as Clob, Blob and Varchar2. The size is represented in bytes for binary datatypes and characters for the Unicode string types. The count for string types does not include the terminating character. The size is inferred from the actual size of the value, if it is not explicitly set. For an output parameter, the size of each value is set by ODP.NET. The ArrayBindSize property is ignored for fixed length datatypes.
• ArrayBindStatus Property
  The ArrayBindStatus property is an array of OracleParameterStatus values specifying status of each corresponding value in an array for a parameter. This property is similar to the Status property of OracleParameter, except that ArrayBindStatus specifies the status for each value in an array.
  Before the execution, the application must populate the ArrayBindStatus property and after the execution, ODP.NET populates it. Before the execution, an application using ArrayBindStatus can specify a NULL value for the corresponding element in the array for a parameter. After the execution, ODP.NET populates the ArrayBindStatus array, indicating whether the corresponding element in the array has a NULL value or if data truncation occurred when the value was fetched.

Error Handling for Array Binding

If an error occurs during an Array Bind execution, it can be difficult to determine which element in the Value property caused the error. ODP.NET provides a way to determine the row where the error occurred, making it easier to find the element in the row that caused the error.

When an OracleException is thrown during an Array Bind execution, the OracleErrorCollection contains one or more OracleError objects. Each of these OracleError objects represents an individual error that occurred during the execution and contains a provider-specific property, ArrayBindIndex, which indicates the row number at which the error occurred.

Code Snippet

try
{
// An Array Bind execution errors out
}
catch (OracleException e)
{
Console.WriteLine ("OracleException {0} occured", e.Message);
for (int i = 0; i < e.Errors.Count; i++)
Console.WriteLine("Array Bind Error {0} occured at Row Number {1}",
e.Errors[i].Message,e.Errors[i].ArrayBindIndex);
}