如何獲取電子郵件地址作爲用戶名每

Question

我想從sqlite的數據獲取usermail當我選擇的用戶名我想這碼得到錯誤

 android.database.sqlite.SQLiteException: no such column: royal (code 1): , while compiling: SELECT userName, compMail FROM Records WHERE userName= royal 

DBController.java

public String returnickname(long l) { 
     // TODO Auto-generated method stub 
     String[] coloumns = new String[] { COLUMN_NAME, COLUMN_TYPE,COLUMN_COMP_MAIL };//calling elements in an array 
     Cursor c = db.query(DATABASE_NAME, coloumns,COLUMN_NAME + "=" + l, null, null, null, null); 
     if (c != null) { 
      c.moveToFirst(); 
      String nickname = c.getString(2); // since name is in position 2 ie 3rd coloumn 
      return nickname; 
     } 
     return null; 
    } 

VehicleReceipt.java

if (spinner.getId()== R.id.insu_comp_spinner) { 

      String label = parent.getItemAtPosition(position).toString(); 


      long l=Long.parseLong(label); 
      String returnedname=controller.returnickname(l); 
      editICM.setText(returnedname); 

我想通過微調選擇

來提取數據

例如：select contact_no where name ='ram';

當我選擇ram set rams contact_no來編輯文本。

Answer 1

當您發佈的例外說：

android.database.sqlite.SQLiteException：沒有這樣的列：皇家（代碼1）

如果你把你的查詢String值沒有引號，數據庫將假定它是一個列名。

你編譯的查詢是：

SELECT userName, compMail FROM Records WHERE userName=royal 

這應該是：

SELECT userName, compMail FROM Records WHERE userName='royal' 

---

包裹值引號'。試着改變你的查詢：

Cursor c = db.query(DATABASE_NAME, coloumns,COLUMN_NAME + "='" + l + "'", null, null, null, null); 

這將使你的方法是這樣的：

public String returnickname(long l) { 
    // TODO Auto-generated method stub 
    String[] coloumns = new String[] { COLUMN_NAME, COLUMN_TYPE,COLUMN_COMP_MAIL };//calling elements in an array 
    Cursor c = db.query(DATABASE_NAME, coloumns,COLUMN_NAME + "='" + l + "'", null, null, null, null); 
    if (c != null) { 
     c.moveToFirst(); 
     String nickname = c.getString(2); // since name is in position 2 ie 3rd coloumn 
     return nickname; 
    } 
    return null; 
} 

你可以閱讀有關的SQLite查詢的基礎知識在這裏：SQLite SELECT Query