when timestamp is null

hi,

i want to update rows of a table where the column defined

as type timestamp is null.

update cust set cust_svc_start_dt = cust_svc_end_dt -1

where cust_svc_start_dt is null;

<bold>ERROR: Unable to convert null timestamp to date

</bold>

how can i get around this? i've tried to_char and casting

as date, time, etc. to no avail.

TIA,

mikeo

\d cust

Table "cust"

Attribute | Type | Modifier

-------------------+-------------+----------

cust_id | varchar(15) | not null

cut_id | varchar(6) |

cust_name | varchar(50) |

cust_division | varchar(6) |

cust_svc_start_dt | timestamp |

cust_svc_end_dt | timestamp |

cust_valid | varchar(1) |

cust_bill_loc_id | varchar(6) |

wu_id | varchar(10) |

cust_timestamp | timestamp |

agt_id | integer |

rse_id | integer |

bd_id | varchar(6) |

cust_email | varchar(50) |

cust_stream | integer |

br_cycle | bigint |