private void btnLogin_Click (object sender, EventArgs e) 
{

If (this. TxtUserName. Text. The Trim ()=="") 
{
MessageBox. Show (" user name cannot be empty ", "prompt"); 
return; 
} 

//the connection string 
String STR="server=localhost; The database=addressBook; Uid=sa; The PWD=123456 "; 

//connection object 
SqlConnection con=new SqlConnection (); 
Con. The ConnectionString=STR; 

//open the database 
Con. The Open (); 

//execute the command 

//CMD. Connection=con; 

The DataSet ds=new DataSet (); 
String st="select the User, the Password from the users where the User='" + txtUserName. Text. The ToString (). The Trim () +"' and Password='" + txtPassword. Text. The ToString (). The Trim () + "' "; 
SqlCommand CMD=new SqlCommand (st, con); 
SqlDataReader Dr=CMD. ExecuteReader (); 
Try 
{

If (Dr. Read ()) 
{
This. Hide (); 
MainForm FRM=new MainForm (); 
FRM. The Show (); 
} 


The else 
{
MessageBox. Show (" account and password error, please input again!" , "tip"); 
TxtPassword. Text=""; 
Enclosing the Focus (); 
} 
} 
The catch (Exception ex) 
{
MessageBox. Show (ex. ToString ()); 
} 
The finally 
{

CMD. The Dispose (); 
Con. The Dispose (); 
} 
} 

CodePudding user response:

Can set static connection test successful inside attribute? Don't write code to connect,

CodePudding user response:

Tried, or that problem, database connection: no problem

CodePudding user response:

Estimation is the query string concatenation appear a mistake, do not recommend this recklessly, suggested parameter binding way,
You can put your query string output look,