Method interface of SQL::Eval

new

Constructor; use it like this:

    $eval = SQL::Eval->new(\%attr);
    

Blesses the hash ref \%attr into the SQL::Eval class (or a subclass).

param

Used for getting or setting input parameters, as in the SQL query

    INSERT INTO foo VALUES (?, ?);
    

Example:

    $eval->param(0, $val);        # Set parameter 0
    $eval->param(0);              # Get parameter 0
    

params

Used for getting or setting the complete array of input parameters. Example:

    $eval->params($params);       # Set the array
    $eval->params();              # Get the array
    

table

Returns or sets a table object. Example:

    $eval->table('foo', $fooTable);  # Set the 'foo' table object
    $eval->table('foo');             # Return the 'foo' table object
    

column

Return the value of a column with a given name; example:

    $col = $eval->column('foo', 'id');  # Return the 'id' column of
                                        # the current row in the
                                        # 'foo' table
    

This is equivalent to and a shorthand for

    $col = $eval->table('foo')->column('id');
    

_gen_access_fastpath

Return a subroutine reference for fast accessing columns for read-only access. This routine simply returns the "_gen_access_fastpath" of the referenced table.

Method interface of SQL::Eval::Table

new

Constructor; use it like this:

    $eval = SQL::Eval::Table->new(\%attr);
    

Blesses the hash ref \%attr into the SQL::Eval::Table class (or a subclass).

The following attributes are used by "SQL::Eval::Table":

row

Used to get the current row as an array ref. Do not confuse getting the current row with the fetch_row method! In fact this method is valid only after a successful "$table->fetchrow()". Example:

    $row = $table->row();
    

column

Get the column with a given name in the current row. Valid only after a successful "$table->fetchrow()". Example:

    $col = $table->column($colName);
    

column_num

Return the number of the given column name. Column numbers start with 0. Returns undef, if a column name is not defined, so that you can use this for verifying column names. Example:

    $colNum = $table->column_num($colNum);
    

col_nums

Returns an hash ref of column names with the column names as keys and the column indexes as the values.

col_names

Returns an array ref of column names ordered by their index within the table.

capability

Returns a boolean value whether the table has the specified capability or not. This method might be overridden by derived classes, but ensure that in that case the parent capability method is called when the derived class does not handle the requested capability.

The following capabilities are used (and requested) by SQL::Statement:

The above methods are implemented by SQL::Eval::Table. The following methods are not, so that they *must* be implemented by the subclass. See the "DBD::DBM::Table" or "DBD::CSV::Table" for example.

drop

Drops the table. All resources allocated by the table must be released after "$table-"drop($data)>.

fetch_row

Fetches the next row from the table. Returns "undef", if the last row was already fetched. The argument $data is for private use of the subclass. Example:

    $row = $table->fetch_row($data);
    

Note, that you may use

    $row = $table->row();
    

for retrieving the same row again, until the next call of "fetch_row".

"SQL::Statement" requires that the last fetched row is available again and again via "$table-"row()>.

push_row

As fetch_row except for storing rows. Example:

    $table->push_row($data, $row);
    

push_names

Used by the CREATE TABLE statement to set the column names of the new table. Receives an array ref of names. Example:

    $table->push_names($data, $names);
    

seek

Similar to the seek method of a filehandle; used for setting the number of the next row being written. Example:

    $table->seek($data, $whence, $rowNum);
    

Actually the current implementation only uses "seek($data, 0, 0)" (first row) and "seek($data, 2, 0)" (beyond last row, end of file).

truncate

Truncates a table after the current row. Example:

    $table->truncate($data);