ADO WEB DEVELOPER C#

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Table of Contents

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Command Object

The ADO Command object is used to execute a single query against a database. The query can perform actions like creating, adding, retrieving, deleting or updating records.

If the query is used to retrieve data, the data will be returned as a RecordSet object. This means that the retrieved data can be manipulated by properties, collections, methods, and events of the Recordset object.

The major feature of the Command object is the ability to use stored queries and procedures with parameters.

ProgID

set objCommand=Server.CreateObject("ADODB.command")

Properties

Property Description ActiveConnection Sets or returns a definition for a connection if the connection is closed, or the current Connection object if the connection is open CommandText Sets or returns a provider command CommandTimeout Sets or returns the number of seconds to wait while attempting to execute a command CommandType Sets or returns the type of a Command object Name Sets or returns the name of a Command object Prepared Sets or returns a Boolean value that, if set to True, indicates that the command should save a prepared version of the query before the first execution State Returns a value that describes if the Command object is open, closed, connecting, executing or retrieving data

Methods

Method Description Cancel Cancels an execution of a method CreateParameter Creates a new Parameter object Execute Executes the query, SQL statement or procedure in the CommandText property

Collections

Collection Description Parameters Contains all the Parameter objects of a Command Object Properties Contains all the Property objects of a Command Object

Connection Object

The ADO Connection Object is used to create an open connection to a data source. Through this connection, you can access and manipulate a database.

If you want to access a database multiple times, you should establish a connection using the Connection object. You can also make a connection to a database by passing a connection string via a Command or Recordset object. However, this type of connection is only good for one specific, single query.

ProgID

set objConnection=Server.CreateObject("ADODB.connection")

Properties

Property Description Attributes Sets or returns the attributes of a Connection object CommandTimeout Sets or returns the number of seconds to wait while attempting to execute a command ConnectionString Sets or returns the details used to create a connection to a data source ConnectionTimeout Sets or returns the number of seconds to wait for a connection to open CursorLocation Sets or returns the location of the cursor service DefaultDatabase Sets or returns the default database name IsolationLevel Sets or returns the isolation level Mode Sets or returns the provider access permission Provider Sets or returns the provider name State Returns a value describing if the connection is open or closed Version Returns the ADO version number

Methods

Method Description BeginTrans Begins a new transaction Cancel Cancels an execution Close Closes a connection CommitTrans Saves any changes and ends the current transaction Execute Executes a query, statement, procedure or provider specific text Open Opens a connection OpenSchema Returns schema information from the provider about the data source RollbackTrans Cancels any changes in the current transaction and ends the transaction

Events

Note: You cannot handle events using VBScript or JScript (only Visual Basic, Visual C++, and Visual J++ languages can handle events).

Event Description BeginTransComplete Triggered after the BeginTrans operation CommitTransComplete Triggered after the CommitTrans operation ConnectComplete Triggered after a connection starts Disconnect Triggered after a connection ends ExecuteComplete Triggered after a command has finished executing InfoMessage Triggered if a warning occurs during a ConnectionEvent operation RollbackTransComplete Triggered after the RollbackTrans operation WillConnect Triggered before a connection starts WillExecute Triggered before a command is executed

Collections

Collection Description Errors Contains all the Error objects of the Connection object Properties Contains all the Property objects of the Connection object

Error Object

The ADO Error object contains details about data access errors that have been generated during a single operation.

ADO generates one Error object for each error. Each Error object contains details of the specific error, and are stored in the Errors collection. To access the errors, you must refer to a specific connection.

To loop through the Errors collection:

Syntax

objErr.property

Properties

Property Description Description Returns an error description HelpContext Returns the context ID of a topic in the Microsoft Windows help system HelpFile Returns the full path of the help file in the Microsoft Windows help system NativeError Returns an error code from the provider or the data source Number Returns a unique number that identifies the error Source Returns the name of the object or application that generated the error SQLState Returns a 5-character SQL error code

Field Object

The ADO Field object contains information about a column in a Recordset object. There is one Field object for each column in the Recordset.

ProgID

set objField=Server.CreateObject("ADODB.field")

Properties

Property Description ActualSize Returns the actual length of a field's value Attributes Sets or returns the attributes of a Field object DefinedSize Returns the defined size of a field Name Sets or returns the name of a Field object NumericScale Sets or returns the number of decimal places allowed for numeric values in a Field object OriginalValue Returns the original value of a field Precision Sets or returns the maximum number of digits allowed when representing numeric values in a Field object Status Returns the status of a Field object Type Sets or returns the type of a Field object UnderlyingValue Returns the current value of a field Value Sets or returns the value of a Field object

Methods

Method Description AppendChunk Appends long binary or character data to a Field object GetChunk Returns all or a part of the contents of a large text or binary data Field object

Collections

Collection Description Properties Contains all the Property objects for a Field object

Parameter Object

The ADO Parameter object provides information about a single parameter used in a stored procedure or query.

A Parameter object is added to the Parameters Collection when it is created. The Parameters Collection is associated with a specific Command object, which uses the Collection to pass parameters in and out of stored procedures and queries.

Parameters can be used to create Parameterized Commands. These commands are (after they have been defined and stored) using parameters to alter some details of the command before it is executed. For example, an SQL SELECT statement could use a parameter to define the criteria of a WHERE clause.

There are four types of parameters: input parameters, output parameters, input/output parameters and return parameters.

Syntax

Properties

Property Description Attributes Sets or returns the attributes of a Parameter object Direction Sets or returns how a parameter is passed to or from a procedure Name Sets or returns the name of a Parameter object NumericScale Sets or returns the number of digits stored to the right side of the decimal point for a numeric value of a Parameter object Precision Sets or returns the maximum number of digits allowed when representing numeric values in a Parameter Size Sets or returns the maximum size in bytes or characters of a value in a Parameter object Type Sets or returns the type of a Parameter object Value Sets or returns the value of a Parameter object

Methods

Method Description AppendChunk Appends long binary or character data to a Parameter object Delete Deletes an object from the Parameters Collection

Property Object

The ADO Property object represents a dynamic characteristic of an ADO object that is defined by the provider.

Each provider that talks with ADO has different ways of interacting with ADO. Therefore, ADO needs to store information about the provider in some way. The solution is that the provider gives specific information (dynamic properties) to ADO. ADO stores each provider property in a Property object that is again stored in the Properties Collection. The Collection is assigned to either a Command object, Connection object, Field object, or a Recordset object.

ProgID

set objProperty=Server.CreateObject("ADODB.property")

Properties

Property Description Attributes Returns the attributes of a Property object Name Sets or returns a the name of a Property object Type Returns the type of a Property object Value Sets or returns the value of a Property object

Record Object (ADO version 2.5)

The ADO Record object is used to hold a row in a Recordset, a directory, or a file from a file system.

Only structured databases could be accessed by ADO in versions prior 2.5. In a structured database, each table has the exact same number of columns in each row, and each column is composed of the same data type.

The Record object allows access to data-sets where the number of columns and/or the data type can be different from row to row.

Syntax

Properties

Property Description ActiveConnection Sets or returns which Connection object a Record object belongs to Mode Sets or returns the permission for modifying data in a Record object ParentURL Returns the absolute URL of the parent Record RecordType Returns the type of a Record object Source Sets or returns the src parameter of the Open method of a Record object State Returns the status of a Record object

Methods

Method Description Cancel Cancels an execution of a CopyRecord, DeleteRecord, MoveRecord, or Open call Close Closes a Record object CopyRecord Copies a file or directory to another location DeleteRecord Deletes a file or directory GetChildren Returns a Recordset object where each row represents the files in the directory MoveRecord Moves a file or a directory to another location Open Opens an existing Record object or creates a new file or directory

Collections

Collection Description Properties A collection of provider-specific properties Fields Contains all the Field objects in the Record object

The Fields Collection's Properties

Property Description Count Returns the number of items in the fields collection. Starts at zero. Example: countfields = rec.Fields.Count Item(named_item/number) Returns a specified item in the fields collection. Example: itemfields = rec.Fields.Item(1)

or

itemfields = rec.Fields.Item("Name")

Recordset Object

The ADO Recordset object is used to hold a set of records from a database table. A Recordset object consist of records and columns (fields).

In ADO, this object is the most important and the most used object to manipulate data from a database.

ProgID

set objRecordset=Server.CreateObject("ADODB.recordset")



When you first open a Recordset, the current record pointer will point to the first record and the BOF and EOF properties are False. If there are no records, the BOF and EOF property are True.

Recordset objects can support two types of updating:

  • Immediate updating - all changes are written immediately to the database once you call the Update method.
  • Batch updating - the provider cache multiple changes and then send them to the database with the UpdateBatch method.

In ADO there are 4 different cursor types defined:

  • Dynamic cursor - Allows you to see additions, changes, and deletions by other users.
  • Keyset cursor - Like a dynamic cursor, except that you cannot see additions by other users, and it prevents access to records that other users have deleted. Data changes by other users will still be visible.
  • Static cursor - Provides a static copy of a recordset for you to use to find data or generate reports. Additions, changes, or deletions by other users will not be visible. This is the only type of cursor allowed when you open a client-side Recordset object.
  • Forward-only cursor - Allows you to only scroll forward through the Recordset. Additions, changes, or deletions by other users will not be visible.

The cursor type can be set by the CursorType property or by the CursorType parameter in the Open method.

Note: Not all providers supports all methods or properties of the Recordset object.

Properties

Property Description AbsolutePage Sets or returns a value that specifies the page number in the Recordset object AbsolutePosition Sets or returns a value that specifies the ordinal position of the current record in the Recordset object ActiveCommand Returns the Command object associated with the Recordset ActiveConnection Sets or returns a definition for a connection if the connection is closed, or the current Connection object if the connection is open BOF Returns true if the current record position is before the first record, otherwise false Bookmark Sets or returns a bookmark. The bookmark saves the position of the current record CacheSize Sets or returns the number of records that can be cached CursorLocation Sets or returns the location of the cursor service CursorType Sets or returns the cursor type of a Recordset object DataMember Sets or returns the name of the data member that will be retrieved from the object referenced by the DataSource property DataSource Specifies an object containing data to be represented as a Recordset object EditMode Returns the editing status of the current record EOF Returns true if the current record position is after the last record, otherwise false Filter Sets or returns a filter for the data in a Recordset object Index Sets or returns the name of the current index for a Recordset object LockType Sets or returns a value that specifies the type of locking when editing a record in a Recordset MarshalOptions Sets or returns a value that specifies which records are to be returned back to the server MaxRecords Sets or returns the maximum number of records to return to a Recordset object from a query PageCount Returns the number of pages with data in a Recordset object PageSize Sets or returns the maximum number of records allowed on a single page of a Recordset object RecordCount Returns the number of records in a Recordset object Sort Sets or returns the field names in the Recordset to sort on Source Sets a string value or a Command object reference, or returns a String value that indicates the data source of the Recordset object State Returns a value that describes if the Recordset object is open, closed, connecting, executing or retrieving data Status Returns the status of the current record with regard to batch updates or other bulk operations StayInSync Sets or returns whether the reference to the child records will change when the parent record position changes

Methods

Method Description AddNew Creates a new record Cancel Cancels an execution CancelBatch Cancels a batch update CancelUpdate Cancels changes made to a record of a Recordset object Clone Creates a duplicate of an existing Recordset Close Closes a Recordset CompareBookmarks Compares two bookmarks Delete Deletes a record or a group of records Find Searches for a record in a Recordset that satisfies a specified criteria GetRows Copies multiple records from a Recordset object into a two-dimensional array GetString Returns a Recordset as a string Move Moves the record pointer in a Recordset object MoveFirst Moves the record pointer to the first record MoveLast Moves the record pointer to the last record MoveNext Moves the record pointer to the next record MovePrevious Moves the record pointer to the previous record NextRecordset Clears the current Recordset object and returns the next Recordset object by looping through a series of commands Open Opens a database element that gives you access to records in a table, the results of a query, or to a saved Recordset Requery Updates the data in a Recordset by re-executing the query that made the original Recordset Resync Refreshes the data in the current Recordset from the original database Save Saves a Recordset object to a file or a Stream object Seek Searches the index of a Recordset to find a record that matches the specified values Supports Returns a boolean value that defines whether or not a Recordset object supports a specific type of functionality Update Saves all changes made to a single record in a Recordset object UpdateBatch Saves all changes in a Recordset to the database. Used when working in batch update mode

Events

Note: You cannot handle events using VBScript or JScript (only Visual Basic, Visual C++, and Visual J++ languages can handle events).

Event Description EndOfRecordset Triggered when you try to move to a record after the last record FetchComplete Triggered after all records in an asynchronous operation have been fetched FetchProgress Triggered periodically in an asynchronous operation, to state how many more records that have been fetched FieldChangeComplete Triggered after the value of a Field object change MoveComplete Triggered after the current position in the Recordset has changed RecordChangeComplete Triggered after a record has changed RecordsetChangeComplete Triggered after the Recordset has changed WillChangeField Triggered before the value of a Field object change WillChangeRecord Triggered before a record change WillChangeRecordset Triggered before a Recordset change WillMove Triggered before the current position in the Recordset changes

Collections

Collection Description Fields Indicates the number of Field objects in the Recordset object Properties Contains all the Property objects in the Recordset object

The Fields Collection's Properties

Property Description Count Returns the number of items in the fields collection. Starts at zero. Example: countfields = rs.Fields.Count Item(named_item/number) Returns a specified item in the fields collection. Example: itemfields = rs.Fields.Item(1)

or

itemfields = rs.Fields.Item("Name")

The Properties Collection's Properties

Property Description Count Returns the number of items in the properties collection. Starts at zero. Example: countprop = rs.Properties.Count Item(named_item/number) Returns a specified item in the properties collection. Example: itemprop = rs.Properties.Item(1)

or

itemprop = rs.Properties.Item("Name")

Stream Object (ADO version 2.5)

The ADO Stream Object is used to read, write, and manage a stream of binary data or text.

A Stream object can be obtained in three ways:

  • From a URL pointing to a document, a folder, or a Record object
  • By instantiating a Stream object to store data for your application
  • By opening the default Stream object associated with a Record object

Syntax

Properties

Property Description CharSet Sets or returns a value that specifies into which character set the contents are to be translated. This property is only used with text Stream objects (type is adTypeText) EOS Returns whether the current position is at the end of the stream or not LineSeparator Sets or returns the line separator character used in a text Stream object Mode Sets or returns the available permissions for modifying data Position Sets or returns the current position (in bytes) from the beginning of a Stream object Size Returns the size of an open Stream object State Returns a value describing if the Stream object is open or closed Type Sets or returns the type of data in a Stream object

Methods

Method Description Cancel Cancels an execution of an Open call on a Stream object Close Closes a Stream object CopyTo Copies a specified number of characters/bytes from one Stream object into another Stream object Flush Sends the contents of the Stream buffer to the associated underlying object LoadFromFile Loads the contents of a file into a Stream object Open Opens a Stream object Read Reads the entire stream or a specified number of bytes from a binary Stream object ReadText Reads the entire stream, a line, or a specified number of characters from a text Stream object SaveToFile Saves the binary contents of a Stream object to a file SetEOS Sets the current position to be the end of the stream (EOS) SkipLine Skips a line when reading a text Stream Write Writes binary data to a binary Stream object WriteText Writes character data to a text Stream object ADO WEB DEVELOPER C#

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