我已经安装了“mysql”。现在，我想安装或启用“mysqlnd”。
为此我使用
sudo apt-get install php5-mysqlnd
但是在终端上出现了输出。
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package php5-mysqlnd is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
php5-mysql
N: Ignoring 'build' in directory '/etc/apt/sources.list.d/' as it is not a regular file
N: Ignoring 'build' in directory '/etc/apt/sources.list.d/' as it is not a regular file
E: Package 'php5-mysqlnd' has no installation candidate
任何人都有想法，我做错了什么？