C#使用Connection连接数据库

判断是否输入了数据库名称（没输入）

if (textBox1.Text=="")
{
    MessageBox.Show("请输入要连接的数据库名称！");
}

声明一个字符串，用于存储连接数据库字符串

string ConStr = "server=.;database=" + textBox1.Text.Trim() + ";uid=sa;pwd=123";

创建一个SqlConnection对象

SqlConnection conn = new SqlConnection(ConStr);

打开连接

conn.Open();

判断当前连接状态

if (conn.State == ConnectionState.Open)
{
    label.Content = "数据库【"+ textBox1.Text.Trim()+"】";
}

完整代码

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            if (textBox1.Text=="")
            {
                MessageBox.Show("请输入要连接的数据库名称！");
            }
            else
            {
                try
                {
                    string ConStr = "server=.;database=" + textBox1.Text.Trim() + ";uid=sa;pwd=123456789";
                    SqlConnection conn = new SqlConnection(ConStr);
                    conn.Open();
                    if (conn.State == ConnectionState.Open)
                    {
                        label.Content = "数据库【"+ textBox1.Text.Trim()+"】";
                    }
                }
                catch (Exception)
                {

                    MessageBox.Show("连接数据库失败！！！");
                }
            }
        }
    }

窗体的

<Window x:Class="测试数据库的交互.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:测试数据库的交互"
        mc:Ignorable="d" 
        Title="测试" Width="300" Height="300" >

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition Width="0*"/>
        </Grid.ColumnDefinitions>
        <Button Content="Button" HorizontalAlignment="Left" Margin="100,160,0,0" VerticalAlignment="Top" Width="75" Height="19" Click="Button_Click"/>
        <TextBox x:Name="textBox1" HorizontalAlignment="Left" Height="23" Margin="80,120,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
        <Label x:Name="label" Content="Label" HorizontalAlignment="Left" Margin="100,80,0,0" VerticalAlignment="Top"/>

    </Grid>
</Window>

如图