连接字符串配置文件中存储

SqlConnection conn = new SqlConnection();

//手写

//string connStr = "server=.;database=TestBase;uid=lyc;pwd=123456";

//SqlConnectionStringBuilder生成连接字符串

//SqlConnectionStringBuilder connStrBuilder = new SqlConnectionStringBuilder();

//connStrBuilder.DataSource = ".";//设置数据源

//connStrBuilder.InitialCatalog = "TestBase";//数据库名

//connStrBuilder.UserID = "lyc";//账号

//connStrBuilder.Password = "123456";//密码

//connStrBuilder.Pooling = false;//禁用连接池

//string connStr = connStrBuilder.ConnectionString;

//读取配置文件里的连接字符串

//配置到文件中   写哪个位置？ （推荐） connectionStrings节点中  appSettings节点中

//string connStr =   ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;//读取连接字符串

string connStr = ConfigurationManager.AppSettings["connStr"].ToString();

conn.ConnectionString = connStr ;

//连接字符串如果任何一个元素设置不正确，都不能正常打开conn

conn.Open();

conn.Close();

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

<startup>

<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />

</startup>

<connectionStrings>

<add name ="connStr" connectionString="server=.;database=TestBase;uid=lyc;pwd=123456" providerName ="System.Data.SqlClient"/>

</connectionStrings>

<appSettings>

<add key ="connStr" value ="server=.;database=TestBase;uid=lyc;pwd=123456"/>

</appSettings>

</configuration>