nginx配置phpmyadmin虚拟目录的问题

server {listen       80;
server_name ceshi3.com;
#charset koi8-r;
#access_log  logs/host.access.log  main;
# Load configuration files for the default server block.
include /etc/nginx/default.d/*.conf;
location / {
root   /www/html/ceshi3.com/htdocs;
index  index.html index.php index.htm;
}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000#
location ~  \.php$ {
# root           html;
fastcgi_pass   127.0.0.1:9000;
fastcgi_index  index.php;
fastcgi_param  SCRIPT_FILENAME  /www/html/ceshi3.com/htdocs$fastcgi_script_name;
include        fastcgi_params;
}
location /phpmyadmin {
alias /usr/share/phpMyAdmin/;
index index.php;}
location ~ /phpmyadmin/.+\.php$ {
if ($fastcgi_script_name ~ /phpmyadmin/(.+\.php.*)$) {
set $valid_fastcgi_script_name $1;}
include fastcgi_params;
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /usr/share/phpMyAdmin/$valid_fastcgi_script_name;
}
}但是这样配置之后phpmyadmin打不开，phpmyadmin不在网站根目录下，用的alias定义虚拟目录，如果我把 location ~  \.php$这个删掉，phpmyadmin就可以打开了，但是这样网站首页如果是php的，那么打开首页就会变成下载php文件了，说明php解析不成功，这是怎么回事！
以上语法有错误吗，为什么有冲突呢？