检查两个以上值的重复项，如果没有重复项，则插入查询
检查两个以上值的重复项，如果没有重复项，则插入查询
提问于 2019-04-27 15:47:24
备注：
我有两个键列，(Name(primary键)，Email__(primary键)
我已经插入了两行的。
第一行是name=ema email=ema@gmail.com，第二行是name=ena email=fe。
现在，当我想要插入一个新的记录时，它只检查第一行，并且检查起作用，但是如果我想要插入name=ena和email=something，它不会检查第二行。有人能建议我如何克服这个问题吗？
try
{
Connection connection=DriverManager.getConnection("jdbc:mysql://localhost:3306/testing","root","");
//block of code to check user exists or not.
//Statement statement = connection.createStatement();
PreparedStatement Pstatement;
String query = "select Name,Email from detail";
PreparedStatement ps = connection.prepareStatement(query);
ResultSet rs = ps.executeQuery() ;
if(rs.next())
{
//from database
String name_db1 = rs.getString("Name").trim(); //using trim removes all white spaces
String email_db2 = rs.getString("Email").trim();
//from user GUI
String entered_name = name.getText().trim(); //using trim removes all white spaces
String entered_email = email.getText().trim();
boolean valid = true;
if(entered_name.equals(""))
{
JOptionPane.showMessageDialog(null,"Enter name");
valid = false;
}
else if(name_db1.equals(entered_name))
{
JOptionPane.showMessageDialog(null,"Enter name taken");
name.setText(null);
valid = false;
}
else if(entered_email.equals(""))
{
JOptionPane.showMessageDialog(null,"Enter email");
valid = false;
}
else if(email_db2.equals(entered_email))
{
JOptionPane.showMessageDialog(null,"email taken");
email.setText(null);
valid = false;
}
else if(valid == true)
{
Pstatement=connection.prepareStatement("insert into detail values(?,?)");
//Specifying the values of preparestatement parameter
Pstatement.setString(1,name.getText());
Pstatement.setString(2,email.getText());
Pstatement.executeUpdate();
JOptionPane.showMessageDialog(null,"registration successful");
//x++;
}
}
else
{
//incase if the user click without filling up the fields
JOptionPane.showMessageDialog(null,"not yet registered");
}
}
catch(SQLException e)
{
e.printStackTrace();
}回答 1
Stack Overflow用户
发布于 2019-04-28 01:24:25
最后，我已经弄清楚了逻辑，我只需要为姓名和电子邮件创建一个单独的查询。这样我可以搜索两个以上的值:D.如果有任何错误，请让我知道。
try
{
Class.forName("com.mysql.jdbc.Driver");
Connection con = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/testing","root","");
//creating a query for Name
String query1 = "select Name, Email from detail where Name like '"+name.getText()+"'";
PreparedStatement statement1 = con.prepareStatement(query1);
//creating a query for Email
String query2 = "select Name, Email from detail where Email like '"+email.getText()+"'";
PreparedStatement statement2 = con.prepareStatement(query2);
ResultSet result1 = statement1.executeQuery(); //resultset for name
ResultSet result2 = statement2.executeQuery(); //resultset for email
//checking name exception
if (result1.next())
{
String dbasename=result1.getString("Name").toString().trim();
String enteredname=new String(name.getText().trim());
if(enteredname.equals(""))
{
JOptionPane.showMessageDialog(null, "enter name");//valid1 = false;
}
else if(dbasename.equals(enteredname))
{
JOptionPane.showMessageDialog(null, "name taken");//valid1 = false;
name.setText(null);
}
}
//checking email exception
else if(result2.next())
{
String dbaseemail=result2.getString("Email").toString().trim();
String enteredemail=new String(email.getText().trim());
if(enteredemail.equals(""))
{
JOptionPane.showMessageDialog(null, "enter email");//valid1 = false;
}
else if(dbaseemail.equals(enteredemail))
{
JOptionPane.showMessageDialog(null, "email taken");//valid1 = false;
email.setText(null);
}
}
//if no exception is detect exectute the below statement
else
{
PreparedStatement Pstatement=con.prepareStatement("insert into detail values(?,?)");
Pstatement.setString(1,name.getText());
Pstatement.setString(2,email.getText());
Pstatement.executeUpdate();
JOptionPane.showMessageDialog(null,"Registered Successfully");
}
statement1.close();
statement2.close();
con.close();
}
catch(SQLException se){
se.printStackTrace();
}
catch(Exception e)
{
e.printStackTrace();
JOptionPane.showMessageDialog(null, "error during searching");
} 页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55878417
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