请教一个问题：如何从一个列中提取相关的关键字，将它更新到另一列上

----------Function Name: fun_setCity----------
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[fun_setCity]') AND type in (N'TF','FN'))
DROP FUNCTION [dbo].[fun_setCity]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
Create function [dbo].[fun_setCity] (@address varchar(50))
Returns varchar(50)
AS
begin
declare @city varchar(50)
declare @provinceLength int
set @provinceLength=0
declare @localLength int
set @localLength=0
set @localLength=charindex('市',@address)
if @localLength>0
begin
  set @provinceLength=charindex('省',@address)
  if @provinceLength<=0
  begin
    set @provinceLength=charindex('自治区',@address)
    if @provinceLength>0
    set @provinceLength=@provinceLength+2
    else
    set @provinceLength=0
  end
  if @provinceLength>0
  set @city=substring(@address,@provinceLength+1,@localLength-@provinceLength-1)
  else
  begin
    if charindex('北京',@address)>0
     set @city='北京'
    if charindex('上海',@address)>0
     set @city='上海'
    if charindex('天津',@address)>0
     set @city='天津'
    if charindex('重庆',@address)>0
     set @city='重庆'
  end
end
else
  begin
    if charindex('北京',@address)>0
     set @city='北京'
    if charindex('上海',@address)>0
     set @city='上海'
    if charindex('天津',@address)>0
     set @city='天津'
    if charindex('重庆',@address)>0
     set @city='重庆'
  end
return @city
end
Go
--------创建表 Table Name: 表1----------
IF EXISTS (SELECT * FROM sys.tables WHERE object_id = OBJECT_ID(N'[dbo].[表1]') AND type in (N'U'))
DROP TABLE [dbo].[表1]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[表1](
    [客户姓名] [varchar](50) COLLATE Chinese_PRC_CI_AS not NULL,
    [客户地址] [varchar](50) COLLATE Chinese_PRC_CI_AS NULL,
) ON [PRIMARY]
GO
----------添加数据 Table Name: 表1----------
delete from [表1]
GO
insert into [表1]([客户姓名],[客户地址]) values('甲','吉林省长春市**')
GO
insert into [表1]([客户姓名],[客户地址]) values('乙','河南省郑州市**')
GO
insert into [表1]([客户姓名],[客户地址]) values('丙','陕西省西安市**')
GO
insert into [表1]([客户姓名],[客户地址]) values('丁','宁夏回族自治区银川市**')
GO
insert into [表1]([客户姓名],[客户地址]) values('戊','新疆维吾尔自治区克拉玛依市**')
GO
insert into [表1]([客户姓名],[客户地址]) values('己1','北京市海淀区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('己2','北京海淀区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('庚1','上海市浦东新区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('庚2','上海浦东新区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('辛1','重庆市沙坪坝区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('辛2','重庆沙坪坝区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('申1','天津市南开区**')
GO
insert into [表1]([客户姓名],[客户地址]) values('申2','天津南开区**')
GO
-----------------添加字段-----------------------
IF EXISTS (SELECT * FROM sys.tables WHERE object_id = OBJECT_ID(N'[dbo].[表1]') AND type in (N'U'))
begin
    IF not EXISTS (SELECT * FROM syscolumns WHERE name = N'城市')
    begin
    alter table[表1] add [城市] varchar(50)
    end
end
GO
-----------------显示原始表-----------------------
select * from [dbo].[表1]
-----------------------------------
update [dbo].[表1]
set [城市]=[dbo].fun_setCity([客户地址])
----------------更新之后的表------------------
select * from [dbo].[表1]
------------------结束------------------