Class DBI::BaseStatement
In: lib/dbi/base_classes/statement.rb
Parent: Base

StatementHandles are used to encapsulate the process of managing a statement (DDL or DML) and its parameters, sending it to the database, and gathering any results from the execution of that statement.

As with the other `Base` classes, the terms "DBD Required" and "DBD Optional" are defined in DBI::BaseDatabase.

Methods

[]   []=   bind_param   bind_params   cancel   column_info   execute   fetch   fetch_all   fetch_many   fetch_scroll   finish   new  

Attributes

raise_error  [RW] 

Public Class methods

[Source]

# File lib/dbi/base_classes/statement.rb, line 14
        def initialize(attr=nil)
            @attr = attr || {}
        end

Public Instance methods

Get statement attributes.

[Source]

# File lib/dbi/base_classes/statement.rb, line 159
        def [](attr)
            @attr ||= { }
            @attr[attr]
        end

Set statement attributes. DBD Optional.

[Source]

# File lib/dbi/base_classes/statement.rb, line 167
        def []=(attr, value)
            raise NotSupportedError
        end

Bind a parameter to the statement. DBD Required.

The parameter number is numeric and indexes starting at 1. This corresponds to the question marks (?) in the statement from the left-most part of the statement moving forward.

The value may be any ruby type. How these are handled is DBD-dependent, but the vast majority of DBDs will convert these to string inside the query.

[Source]

# File lib/dbi/base_classes/statement.rb, line 29
        def bind_param(param, value, attribs)
            raise NotImplementedError
        end

Take a list of bind variables and bind them successively using bind_param.

[Source]

# File lib/dbi/base_classes/statement.rb, line 74
        def bind_params(*bindvars)
            bindvars.each_with_index {|val,i| bind_param(i+1, val, nil) }
            self
        end

Cancel any result cursors. DBD Optional, but intentionally does not raise any exception as it‘s used internally to maintain consistency.

[Source]

# File lib/dbi/base_classes/statement.rb, line 83
        def cancel
        end

returns result-set column information as array of hashs, where each hash represents one column. See BaseDatabase#columns. DBD Required.

[Source]

# File lib/dbi/base_classes/statement.rb, line 63
        def column_info
            raise NotImplementedError
        end

Execute the statement with the known binds. DBD Required.

[Source]

# File lib/dbi/base_classes/statement.rb, line 36
        def execute
            raise NotImplementedError
        end

Fetch the next row in the result set. DBD Required.

DBI::Row is responsible for formatting the data the DBD provides it.

[Source]

# File lib/dbi/base_classes/statement.rb, line 54
        def fetch
            raise NotImplementedError
        end

Fetch all available rows. Result is Array of DBI::Row.

[Source]

# File lib/dbi/base_classes/statement.rb, line 141
        def fetch_all
            rows = []
            loop do
                row = fetch
                break if row.nil?
                rows << row.dup
            end

            if rows.empty?
                nil
            else
                rows
            end
        end

fetch x rows. The result is Array of DBI::Row.

[Source]

# File lib/dbi/base_classes/statement.rb, line 123
        def fetch_many(cnt)
            rows = []
            cnt.times do
                row = fetch
                break if row.nil?
                rows << row.dup
            end

            if rows.empty?
                nil
            else
                rows
            end
        end

fetch_scroll is provided with a direction and offset and works similar to how seek() is used on files.

The constants available for direction are as follows:

  • SQL_FETCH_NEXT: fetch the next result.
  • SQL_FETCH_LAST: fetch the last result, period.
  • SQL_FETCH_RELATIVE: fetch the result at the offset.

Other constants can be used, but if this method is not supplied by the driver, they will result in a raise of DBI::NotSupportedError.

[Source]

# File lib/dbi/base_classes/statement.rb, line 100
        def fetch_scroll(direction, offset)
            case direction
            when SQL_FETCH_NEXT
                return fetch
            when SQL_FETCH_LAST
                last_row = nil
                while (row=fetch) != nil
                    last_row = row
                end
                return last_row
            when SQL_FETCH_RELATIVE
                raise NotSupportedError if offset <= 0
                row = nil
                offset.times { row = fetch; break if row.nil? }
                return row
            else
                raise NotSupportedError
            end
        end

Close the statement and any result cursors. DBD Required.

Note:Most implementations will fail miserably if you forget to finish your statement handles.

[Source]

# File lib/dbi/base_classes/statement.rb, line 45
        def finish
            raise NotImplementedError
        end

[Validate]