Case Sensitivity in winforms c#

Question

private void btnCustomLogin_Click(object sender, EventArgs e) { if (txtpassword.Text != string.Empty || txtusername.Text != string.Empty) { SetValueForText1 = txtusername.Text; cmd = new SqlCommand("select * from Login where Username='" + txtusername.Text + "' and Password='" + txtpassword.Text + "'", cn); dr = cmd.ExecuteReader(); if (dr.Read()) { dr.Close(); this.Hide(); Home home = new Home(); home.ShowDialog(); } else { dr.Close(); this.Alert("No Account available with
this Username and Password.", Form_Alert.enmType.Error); } } else { this.Alert("Please enter value in all field.", Form_Alert.enmType.Error); } } How do I make both the username and password case sensitive?

Sachin Singh · Answer

Ohh, ok because sql server also uses case insensitive algo. so force sql server to use case sensitive algorithm. private void btnCustomLogin_Click( object sender, EventArgs e) { if (txtpassword.Text != string .Empty || txtusername.Text != string .Empty) { SetValueForText1 = txtusername.Text; cmd = new SqlCommand( "select * from Login whereUsername ='" + txtusername.Text + "' COLLATE SQL_Latin1_General_CP1_CS_AS and Password='" + txtpassword.Text + "' COLLATE SQL_Latin1_General_CP1_CS_AS" , cn); dr = cmd.ExecuteReader(); if (dr.Read()) { dr.Close(); this .Hide(); Home home = new Home(); home.ShowDialog(); } else { dr.Close(); this .Alert( "No Account available with
this Username and Password." , Form_Alert.enmType.Error); } } else { this .Alert( "Please enter value in all field." , Form_Alert.enmType.Error); } }

Srinivasan Ramamoorthi · Answer

If you want to retain case sensitive in sql query, try comparing using binary values as mentioned in my previous answer. It will convert the characters to binary and do comparison. Lower case and Upper case will have different binary values so you will be able to compare with case sensitive values. For password you have to retain case sensitivity by using binary comparison.

Samuel Toh · Answer

I meant sensitive. the word "test" is equals to the word "TEST" and i can login with either of those usernames and Im not sure why.

Srinivasan Ramamoorthi · Answer

There are multiple ways to check this comparison. 1. You can convert to binary and compare it CAST (Username as varbinary ( 100 )) = CAST ( @Username as varbinary )) 2. Use BINARY_CHECKSUM WHERE BINARY_CHECKSUM(Username) = BINARY_CHECKSUM( @Username )

Sachin Singh · Answer

I think you mean case insensitive, because c# is already case sensitive language means 'sachin' not equals 'Sachin'. so, to make case insensitive use private void btnCustomLogin_Click( object sender, EventArgs e) { if (txtpassword.Text != string .Empty || txtusername.Text != string .Empty) { SetValueForText1 = txtusername.Text; cmd = new SqlCommand( "select * from Login where LOWER(Username)='" + txtusername.Text.ToLower() + "' and LOWER(Password)='" + txtpassword.Text.ToLower() + "'" , cn); dr = cmd.ExecuteReader(); if (dr.Read()) { dr.Close(); this .Hide(); Home home = new Home(); home.ShowDialog(); } else { dr.Close(); this .Alert( "No Account available with
this Username and Password." , Form_Alert.enmType.Error); } } else { this .Alert( "Please enter value in all field." , Form_Alert.enmType.Error); } }

Sachin Singh · Answer

Though, the above query solve your problem. It is not the best solution, it would be better if you make your column case sensitive directly. for this alter your table column as alter Table [dbo].[Login] alter column Username varchar(50) collate SQL_Latin1_General_CP1_CS_AS