write the function to fetch a image from mysql databases (datatype blob).

A BLOB is a binary large object that can hold a variable amount of data. The four BLOB  types are TINYBLOB, BLOB,
MEDIUMBLOB, and LONGBLOB. These differ only in the maximum length of the values they can hold. The four TEXT types are
TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT. BLOB columns are treated as binary strings (byte strings).
TEXT columns are treated as non-binary strings (character strings). BLOB  columns have no character set, and sorting
and comparison are based on the numeric values of the bytes in column values. TEXT columns have a character set, and
values are sorted and compared based on the collation of the character set.