/**
* Returns the column descriptions for a table.
*
* The return value is an associative array keyed by the column name,
* as returned by the RDBMS.
*
* The value of each array element is an associative array
* with the following keys:
*
* SCHEMA_NAME => string; name of database or schema
* TABLE_NAME => string;
* COLUMN_NAME => string; column name
* COLUMN_POSITION => number; ordinal position of column in table
* DATA_TYPE => string; SQL datatype name of column
* DEFAULT => string; default expression of column, null if none
* NULLABLE => boolean; true if column can have nulls
* LENGTH => number; length of CHAR/VARCHAR
* SCALE => number; scale of NUMERIC/DECIMAL
* PRECISION => number; precision of NUMERIC/DECIMAL
* UNSIGNED => boolean; unsigned property of an integer type
* PRIMARY => boolean; true if column is part of the primary key
* PRIMARY_POSITION => integer; position of column in primary key
*
* @param string $tableName
* @param string $schemaName
* OPTIONAL
* @return array
*/
public function describeTable($tableName, $schemaName = null)
{
return $this->adapter->describeTable($tableName, $schemaName);
}