delete from 5 table

[adadeh asasasas]

help me please, i've a homeworks
i've 5 tables


table1
++++++++++++++++++++++++++
+ id_kategori + kategori +
++++++++++++++++++++++++++

table2
++++++++++++++++++++++++++++++++++
+ id_jenis + id_kategori + jenis +
++++++++++++++++++++++++++++++++++

table3
+++++++++++++++++++++++++++++
+ id_nama + id_jenis + nama +
+++++++++++++++++++++++++++++

table4
++++++++++++++++++++++++++++++++
+ id_detail + id_nama + detail +
++++++++++++++++++++++++++++++++

table5
++++++++++++++++++++++++++++++++++++++++
+ id_detailnew + id_detail + detailnew +
++++++++++++++++++++++++++++++++++++++++


and when i delete a kategori, then all related data under it deleted too.

i've try :
$hapuskan=mysql_query("delete kategori,jenis,nama_barang,spesifikasi,detail_spesifikasi FROM kategori LEFT JOIN jenis ON kategori.ID_KATEGORI = jenis.ID_KATEGORI LEFT JOIN nama_barang ON jenis.ID_JENIS = nama_barang.ID_JENIS LEFT JOIN spesifikasi ON nama_barang.ID_NAMA = spesifikasi.ID_NAMALEFT JOIN detail_spesifikasi ON spesifikasi.ID_SPEK = detail_spesifikasi.ID_SPEK where ID_KATEGORI=$whate");

and not working x_x