使用varchar作為主鍵的數據類型插入查詢

Question

該程序不接受下面給出的查詢-

 public class loginDaos {

       public void create(loginBean bean) {
           ConnectionPool c = ConnectionPool.getInstance();
           c.initialize();
           Connection con = c.getConnection();
           try {
               String sql = "INSERT INTO login VALUES(?,?,?,?)";
               PreparedStatement pstmt = con.prepareStatement(sql);
               pstmt.setString(1, bean.getCode());
               pstmt.setString(2, bean.getUserid());
               pstmt.setString(3, bean.getPassword());
               pstmt.setString(4, bean.getPosition());
               pstmt.executeUpdate(sql);
           }
       } catch (Exception e) {
           e.printStackTrace();
       }
   }


   public static void main(String args[]) {
       loginDaos ld = new loginDaos();
       loginBean lb = new loginBean("representative", "rep7", "rep7", "r");
       ld.create(lb);

   }
   }

該表是：

 CREATE TABLE login
( userid char(25);
  password varchar(45),
  code char(5),
  position char(),
  PRIMARY KEY (code)
 );

我目前將userid，password，代碼和position的值保留為String。堆棧跟蹤為：

 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?,?,?,?)' at line 1
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
    at com.mysql.jdbc.Util.getInstance(Util.java:381)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1030)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3491)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3423)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)
    at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1564)
    at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1485)
    at login.loginDaos.create(loginDaos.java:33)
    at login.loginDaos.main(loginDaos.java:42)

建立成功（總時間：0秒）

救命！

Answer 1

使用PreparedStatement ，應使用不帶String參數的executeQuery() ， executeUpdate()或execute()方法。

因此，要解決此問題，請使用：

// ....
pstmt.setString(3, bean.getPassword());
pstmt.setString(4, bean.getPosition());
pstmt.executeUpdate();

MySQL驅動程序實現存在一個錯誤，因為JDBC規范指出，在PreparedStatement或CallableStatement實現上CallableStatement時，接受字符串的方法應引發SQLException 。 在這種情況下，它僅引發異常，因為它嘗試直接執行參數化查詢。