Name
DIO — Database Interface Objects
Synopsis
::DIO::handle   interface  ?objectName? (-option | option | -option | option | ...)
Description
	  DIO is designed to be a generic,
	  object-oriented interface to SQL databases.  Its main goal
	  is to be as generic as possible, but since not all SQL
	  databases support the exact same syntaxes, keeping code
	  generic between databases is left to the abilities of the
	  programmer.  DIO simply provides a way to keep the Tcl
	  interface generic.
	
	  interface - The name of the database
	  interface.  Currently supported interfaces are
	  Postgresql and Mysql.
	
	  If objectName is
	  specified, DIO creates an object of that name.  If there is
	  no objectName
	  given, DIO will automatically generate a unique object ID
	
Options
- 
		The hostname of the computer to connect to.  If none
		is given, DIO assumes the local host.
	       
- The port number to connect to on hostname. 
- The username you wish to login to the server as. 
- The password to login to the server with. 
- 
		The name of the database to connect to.
	       
- 
		The default table to use when using built-in commands
		for storing and fetching. 
- 
		The default field to use as the primary key when using
		built-in commands for storing and fetching. 
- 
				If this option is set to 1, DIO will attempt to
				determine an automatic key for
				keyField when storing and fetching.
				In most databases, this requires that the
				sequence also be specified.  In the
				case of MySQL, where sequences do not exist, autokey
				must be used in conjunction with a table which has a
				field specified as AUTO. 
- 
				If DIO is automatically generating keys, it will use
				this sequence as a means to gain a unique number for
				the stored key. 
DIO Object Commands
-  - objectName?array? ?- request?
 
- 
		Execute request as a SQL query and
		create an array from the first record found.  The
		array is set with the fields of the table and the
		values of the record found. 
-  - objectName?autokey? (value | boolean)
 
- 
		Return the current autokey value.  If
		value is specified, it sets a new
		value for the autokey option. 
- 	      Close the current database connection.  This command is
		automatically called when the DIO object is destroyed. 
- 	      Return a count of the number of rows in the
		specified (or current) table. 
- 
		Return the current database.  If
		value is specified, it sets a new
		value for the database.  In most cases, the DIO object
		will automatically connect to the new database when
		this option is changed. 
-  - objectName?delete? ?- key? (-option |- option| ...)
 
- 
		Delete a record from the database where the primary
		key matches key. 
-  - objectName?errorinfo? ?value?
 
- errorinfo contains the value of
		the last error, if any, to occur while executing a
		request.  When a request fails for any reason, this
		variable is filled with the error message from the SQL
		interface package. 
-  - objectName?exec? ?- request?
 
- 
		Execute request as an SQL query.
		When the exec command is called, the query is
		executed, and a DIO result object is returned.  From
		there, the result object can be used to obtain
		information about the query status and records in a
		generic way.  See  Result
		  Object Commands
-  - objectName?fetch? ?- key? ?- arrayName? (-option |- option| ...)
 
- 
		Fetch a record from the database where the primary key
		matches key and store the result in
		an array called arrayName.
	       
-  - objectName?forall? ?- request? ?- arrayName? ?- body?
 
- 
	       Execute an SQL select request and iteratively 
	       fill the array named arrayName
	       with elements named with the matching field names, and
	       values containing the matching values, repeatedly executing 
	       the specified code body
	       for each row returned.
	       
-  - objectName?host? ?- value?
 
- 
		Return the current host value.  If
		value is specified, it sets a new
		value for the host.
	       
-  - objectName?insert? ?- table? ?- arrayName? (-option |- option| ...)
 
- 
		Insert fields from arrayName into the specified table in the database.
	       
- 
		Return the database interface type, such as 
		- Postgresqlor- Mysql.
 
-  - objectName?keyfield? ?- value?
 
- 
		Return the current keyfield.  If
		value is specified, it sets a new
		value for the keyfield.  Value can contain
		multiple key fields as a Tcl list, if the table has multiple
		key fields.
	       
-  - objectName?keys? ?- pattern? (-option |- option| ...)
 
- 
		Return a list of keys in the database.  If
		pattern is specified, only the keys
		matching will be returned.
	       
- 
		Return the last key that was used from
		sequence.  If sequence has not been
		specified, this command returns an empty string.
	       
-  - objectName?list? ?request?
 
- 
		Execute request as a SQL query and
		return a list of the first column of each record
		found.
	       
-  - objectName?makekey? ?- arrayName? ?- keyfield?
 
- 
		Given an array containing key-value pairs and an optional
		list of key fields (we use the object's keyfield if
		none is specified), if we're doing auto keys, create
		and return a new key, otherwise if it's a single key,
		just return its value from the array, else if there are
		multiple keys, return all the keys' values from the
		array as a list.
	       
- Increment sequence and return the
		next key to be used.  If sequence has not been
		specified, this command returns an empty
		string. 
- Open the connection to the current database.  This
		command is automatically called from any command which
		accesses the database. 
-  - objectName?pass? ?- value?
 
- 
		Return the current pass value.  If
		value is specified, it sets a new
		value for the password.
	       
-  - objectName?port? ?- value?
 
- Return the current port value.  If value is
		specified, it sets a new value for the port. 
-  - objectName?quote? ?- string?
 
- Return the specified string quoted in
	      a way that makes it acceptable as a value in a SQL statement.
	       
-  - objectName?search? (-option |- option| ...)
 
- 
		Search the current table, or the specified table if
		-table tableName is specified, for rows matching
		one or more fields as key-value pairs, and return
		a query result handle.
		See  Result Object Commands
- 
		For example,
	 - set res [DIO search -table people -firstname Bob] 
-  - objectName?sequence? ?- value?
 
- 
		Return the current sequence value.  If value is
		specified, it sets a new value for the sequence.
	       
-  - objectName?store? ?- arrayName? (-option |- option| ...)
 
- 
		Store the contents of arrayName in the 
		database, where the keys are the field names and the
		array's values are the corresponding values.  Do an SQL insert 
		if the corresponding row doesn't exist, or an update 
		if it does.
	       - 
		The table name must have been previously set
		or specified with  ?-table?, and the key field(s) must
		have been previously set or specified with
		 ?-keyfield?.
	       - 
		Please note that the store method has significantly higher 
		overhead than
		the update or insert methods, so if you know you are
		inserting a row rather than updating one, it is advisable
		to use the insert method and, likewise, if you know you
		are updating rather than inserting, to use the
		update method.
	       
-  - objectName?string? ?- request?
 
- 
		Execute request as a SQL query and
		return a string containing the first record
		found. 
-  - objectName?table? ?- value?
 
- Return the current table.  If
		value is specified, it sets a new
		value for the table. 
-  - objectName?update? ?- arrayName? (-option |- option| ...)
 
- 
		Updates the row matching the contents of 
		arrayName in the database.  The matching
		row must already exist.  The table can have already been
		set or can be specified with  ?-table?, and
		the key field(s) must either have been set or
		specified with  ?-keyfield?.
	       
-  - objectName?user? ?- value?
 
- 
		Return the current user value.  If
		value is specified, it sets a new
		value for the user.
	       
Result Object Commands
-  - resultObj?autocache? ?- value?
 
- 
		Return the current autocache value.  If
		value is specified, it sets a new
		value for autocache.
	       - 
		If autocache is true, the result object will
		automatically cache rows as you use them.  This means
		that the first time you execute a forall command, each
		row is being cached in the result object itself and
		will no longer need to access the SQL result.
		Default is true.
	       
- 
		Cache the results of the current SQL result in the
		result object itself.  This means that even if the
		database connection is closed and all the results of
		the DIO object are lost, this result object will still
		maintain a cached copy of its records.
	       
-  - resultObj?errorcode? ?- value?
 
- 
		Return the current errorcode value.  If value
		is specified, it sets a new value for errorcode.
	       - 
		errorcode contains the current code from the
		SQL database which specifies the result of the query
		statement which created this object.  This variable
		can be used to determine the success or failure of a
		query.
	       
-  - resultObj?errorinfo? ?- value?
 
- 
		Return the current errorinfo value.  If value
		is specified, it sets a new value for errorinfo.
	       - 
		If an error occurred during the SQL query, DIO
		attempts to set the value of errorinfo to the
		resulting error message.
	       
-  - resultObj?fields? ?- value?
 
- 
		Return the current fields value.  If
		value is specified, it sets a new
		value for fields.
	       - 
		fields contains the list of fields
		used in this query.  The fields are in order of the
		fields retrieved for each row.
	       
-  - resultObj?forall? ?- -type? ?- varName? ?- body?
 
- 
		Execute body over each record in the
		result object.
	       - Types: - 
		      Create
		      - varNameas an array where the indexes are the names of
		      the fields in the table and the values are the
		      values of the current row.
 
- 
		      Set
		      - varNameto a list containing key-value pairs of fields
		      and values from the current row. (-field value
		      -field value)
 
- 
		      Set
		      - varNameto a list that contains the values of the
		      current row.
 
 
-  - resultObj?next? ?- -type? ?- varName?
 
- 
		Retrieve the next record in the result object.
	       - Types: - 
		      Create
		      - varNameas an array where the indexes are the names of
		      the fields in the table and the values are the
		      values of the current row.
 
- 
		      Set
		      - varNameto a list containing key-value pairs of fields
		      and values from the current row. (-field value
		      -field value)
 
- 
		      Set
		      - varNameto a list that contains the values of the
		      current row.
 
 
-  - resultObj?numrows? ?- value?
 
- 
		Return the current numrows value.  If value is
		specified, it sets a new value for numrows.
	       - 
		numrows is the number of rows in this result.
	       
-  - resultObj?resultid? ?- value?
 
- 
		Return the current resultid value.  If value is
		specified, it sets a new value for resultid.
	       - 
		resultid in most databases is the result
		pointer which was given us by the database.  This
		variable is not generic and should not really be used,
		but it's there if you want it.
	       
-  - resultObj?rowid? ?- value?
 
- 
		Return the current rowid value.  If value is
		specified, it sets a new value for rowid.
	       - 
		rowid contains the number of the
		current result record in the result object.  This
		variable should not really be accessed outside of the
		result object, but it's there if you want it.