3. Cursor Objects

arraysize: This read-write attribute specifies the number of rows to fetch at a time internally and is the default number of rows to fetch with the fetchmany() call. It defaults to 1 meaning to fetch a single row at a time. Note that this attribute can drastically affect the performance of a query since it directly affects the number of network round trips that need to be performed.

bindarraysize: This read-write attribute specifies the number of rows to bind at a time and is used when creating variables via setinputsizes() or var(). It defaults to 1 meaning to bind a single row at a time.
NOTE: The DB API definition does not define this attribute.

arrayvar( dataType, value, [size]): Create an array variable associated with the cursor of the given type and size and return a variable object (4). The value is either an integer specifying the number of elements to allocate or it is a list and the number of elements allocated is drawn from the size of the list. If the value is a list, the variable is also set with the contents of the list. If the size is not specified and the type is a string or binary, 4000 bytes (maximum allowable by Oracle) is allocated. This is needed for passing arrays to PL/SQL (in cases where the list might be empty and the type cannot be determined automatically) or returning arrays from PL/SQL.
NOTE: The DB API definition does not define this method.

bindnames( ): Return the list of bind variable names bound to the statement. Note that the statement must have been prepared first.
NOTE: The DB API definition does not define this method.

callfunc( name, returnType,[parameters=[]]): Call a function with the given name. The return type is specified in the same notation as is required by setinputsizes(). The sequence of parameters must contain one entry for each argument that the function expects. The result of the call is the return value of the function.

callproc( name, [parameters=[]]): Call a procedure with the given name. The sequence of parameters must contain one entry for each argument that the procedure expects. The result of the call is a modified copy of the input sequence. Input parameters are left untouched; output and input/output parameters are replaced with possibly new values.

close( ): Close the cursor now, rather than whenever __del__ is called. The cursor will be unusable from this point forward; an Error exception will be raised if any operation is attempted with the cursor.

connection: This read-only attribute returns a reference to the connection object on which the cursor was created.
NOTE: This attribute is an extension to the DB API definition but it is mentioned in PEP 249 as an optional extension.

description: This read-only attribute is a sequence of 7-item sequences. Each of these sequences contains information describing one result column: (name, type, display_size, internal_size, precision, scale, null_ok). This attribute will be None for operations that do not return rows or if the cursor has not had an operation invoked via the execute() method yet.
The type will be one of the type objects defined at the module level.

execute( statement, [parameters], **keywordParameters)

Execute a statement against the database. Parameters may be passed as a dictionary or sequence or as keyword arguments. If the arguments are a dictionary, the values will be bound by name and if the arguments are a sequence the values will be bound by position.

A reference to the statement will be retained by the cursor. If None or the same string object is passed in again, the cursor will execute that statement again without performing a prepare or rebinding and redefining. This is most effective for algorithms where the same statement is used, but different parameters are bound to it (many times).

For maximum efficiency when reusing an statement, it is best to use the setinputsizes() method to specify the parameter types and sizes ahead of time; in particular, None is assumed to be a string of length 1 so any values that are later bound as numbers or dates will raise a TypeError exception.

If the statement is a query, a list of variable objects (4) will be returned corresponding to the list of variables into which data will be fetched with the fetchone(), fetchmany() and fetchall() methods; otherwise, None will be returned.

NOTE: The DB API definition does not define the return value of this method.

executemany( statement, parameters): Prepare a statement for execution against a database and then execute it against all parameter mappings or sequences found in the sequence parameters. The statement is managed in the same way as the execute() method manages it.

executemanyprepared( numIters): Execute the previously prepared and bound statement the given number of times. The variables that are bound must have already been set to their desired value before this call is made. This method was designed for the case where optimal performance is required as it comes at the expense of compatibility with the DB API.
NOTE: The DB API definition does not define this method.

fetchall( ): Fetch all (remaining) rows of a query result, returning them as a list of tuples. An empty list is returned if no more rows are available. Note that the cursor's arraysize attribute can affect the performance of this operation, as internally reads from the database are done in batches corresponding to the arraysize.
An exception is raised if the previous call to execute() did not produce any result set or no call was issued yet.

fetchmany( [numRows=cursor.arraysize])

Fetch the next set of rows of a query result, returning a list of tuples. An empty list is returned if no more rows are available. Note that the cursor's arraysize attribute can affect the performance of this operation.

The number of rows to fetch is specified by the parameter. If it is not given, the cursor's arrysize attribute determines the number of rows to be fetched. If the number of rows available to be fetched is fewer than the amount requested, fewer rows will be returned.

An exception is raised if the previous call to execute() did not produce any result set or no call was issued yet.

fetchone( ): Fetch the next row of a query result set, returning a single tuple or None when no more data is available.
An exception is raised if the previous call to execute() did not produce any result set or no call was issued yet.

fetchraw( [numRows=cursor.arraysize])

Fetch the next set of rows of a query result into the internal buffers of the defined variables for the cursor. The number of rows actually fetched is returned. This method was designed for the case where optimal performance is required as it comes at the expense of compatibility with the DB API.

An exception is raised if the previous call to execute() did not produce any result set or no call was issued yet.

NOTE: The DB API definition does not define this method.

__iter__( ): Returns the cursor itself to be used as an iterator.
NOTE: This method is an extension to the DB API definition but it is mentioned in PEP 249 as an optional extension.

next( ): Fetch the next row of a query result set, using the same semantics as the method fetchone().
NOTE: This method is an extension to the DB API definition but it is mentioned in PEP 249 as an optional extension.

numbersAsStrings: This integer attribute defines whether or not numbers should be returned as strings rather than integers or floating point numbers. This is useful to get around the fact that Oracle floating point numbers have considerably greater precision than C floating point numbers and not require a change to the SQL being executed.
NOTE: The DB API definition does not define this attribute.

parse( statement): This can be used to parse a statement without actually executing it (this step is done automatically by Oracle when a statement is executed).
NOTE: The DB API definition does not define this method.

prepare( statement): This can be used before a call to execute() to define the statement that will be executed. When this is done, the prepare phase will not be performed when the call to execute() is made with None or the same string object as the statement.
NOTE: The DB API definition does not define this method.

rowcount: This read-only attribute specifies the number of rows that have currently been fetched from the cursor (for select statements) or that have been affected by the operation (for insert, update and delete statements).

setinputsizes( *args, **keywordArgs): This can be used before a call to execute() to predefine memory areas for the operation's parameters. Each parameter should be a type object corresponding to the input that will be used or it should be an integer specifying the maximum length of a string parameter. Use keyword arguments when binding by name and positional arguments when binding by position. The singleton None can be used as a parameter when using positional arguments to indicate that no space should be reserved for that position.

setoutputsize( size, [column]): This can be used before a call to execute() to predefine memory areas for the long columns that will be fetched. The column is specified as an index into the result sequence. Not specifying the column will set the default size for all large columns in the cursor.

statement: This read-only attribute provides the string object that was previously prepared with prepare() or executed with execute().
NOTE: The DB API definition does not define this attribute.

var( dataType, [size]): Create a variable associated with the cursor of the given type and size and return a variable object (4). If the size is not specified and the type is a string or binary, 4000 bytes (maximum allowable by Oracle) is allocated; if the size is not specified and the type is a long string or long binary, 128KB is allocated. This method was designed for use with PL/SQL in/out variables where the length or type cannot be determined automatically from the Python object passed in.
NOTE: The DB API definition does not define this method.

Release 4.3.1, documentation updated on April 18, 2007.

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