Android的源码如何检查是否存在记录 [英] Android sqlite how to check if a record exists

问题描述

我想检查记录是否存在。

下面是我已经试过：

MainActivity.class

 公共无效onTextChanged（CharSequence中，诠释开始，诠释之前，诠释计数）{

        的System.out.println（Ontext改为+新的String（s.toString（）））;
        strDocumentFrom = s.toString（）;

        如果（s.toString（）。的isEmpty（））{

        } 其他 {

             尝试{
                 strTransactionDate = dbHelper.getTransactionDateByDocumentNumber（strDocumentFrom）;
                 // strTotalAmount = dbHelper.getTotalAmountByDocumentNumber（strDocumentFrom）;
                 // strVan = dbHelper.getVanByDocumentNumber（strDocumentFrom）;


                 //etTransactionDate.setText(strTransactionDate）;
                 //etTotalAmount.setText(strTotalAmount）;
                 //Log.d("Van，+ strVan）;
                 //etVan.setText(strVan）;

             }赶上（SQLiteException E）{
                 e.printStackTrace（）;
                 Toast.makeText（ReceivingStocksHeader.this，
                         证件号码不存在，Toast.LENGTH_SHORT）.show（）;
             }

        }
 

DBHelper.class

  // TODO中显示记录TO TRANSRCVHEADER
        公共字符串getTransactionDateByDocumentNumber（字符串strDocumentNumber）{
            的String []列=新的String [] {KEY_TRANSACTIONDATE};

            光标C = myDataBase.query（TBL_INTRANS，
                    列，空，
                    NULL，NULL，NULL，NULL，NULL）;

            如果（C！= NULL）{
                c.moveToFirst（）;
                串日期= c.getString（0）;
                返回日期;
            } 其他 {
                Log.d（错误，没有记录存在）;
            }


            返回null;
        }
 

但它没有得到它的catch块显示敬酒。

我在做什么错在这里？

解决方案

 公共静态布尔CheckIsDataAlreadyInDBorNot（字符串表名，
        字符串dbfield，字符串fieldValue方法）{
    SQLiteDatabase SQLDB = EGLifeStyleApplication.sqLiteDatabase;
    查询字符串= +表名+，其中+ dbfield +=+ fieldValue方法选择从*;
    光标光标= sqldb.rawQuery（查询，NULL）;
        如果（cursor.getCount（）＆其中; = 0）{
            cursor.close（）;
            返回false;
        }
    cursor.close（）;
    返回true;
}
 

我希望这是对你有用... 如果记录已经存在于数据库这个函数返回true。否则返回false。

I would like to check whether a record exists or not.

Here is what I've tried:

MainActivity.class

    public void onTextChanged(CharSequence s, int start, int before, int count) {

        System.out.println("Ontext changed " + new String(s.toString()));
        strDocumentFrom = s.toString();         

        if(s.toString().isEmpty()){

        } else {

             try{
                 strTransactionDate = dbHelper.getTransactionDateByDocumentNumber(strDocumentFrom);
                 //strTotalAmount = dbHelper.getTotalAmountByDocumentNumber(strDocumentFrom);
                 //strVan = dbHelper.getVanByDocumentNumber(strDocumentFrom);


                 //etTransactionDate.setText(strTransactionDate);
                 //etTotalAmount.setText(strTotalAmount);
                 //Log.d("Van", "" + strVan);
                 //etVan.setText(strVan);

             } catch (SQLiteException e) {
                 e.printStackTrace();
                 Toast.makeText(ReceivingStocksHeader.this, 
                         "Document number does not exist.", Toast.LENGTH_SHORT).show();
             }

        }

DBHelper.class

            // TODO DISPLAYING RECORDS TO TRANSRCVHEADER
        public String getTransactionDateByDocumentNumber(String strDocumentNumber){
            String[] columns = new String[]{KEY_TRANSACTIONDATE};

            Cursor c = myDataBase.query(TBL_INTRANS, 
                    columns, null, 
                    null, null, null, null, null);

            if(c != null){
                c.moveToFirst();
                String date = c.getString(0);
                return date;
            } else {
                Log.d("Error", "No record exists");
            }


            return null;
        }

But it doesn't get it to the catch block to display the toast.

What am I doing wrong in here?

解决方案

public static boolean CheckIsDataAlreadyInDBorNot(String TableName,
        String dbfield, String fieldValue) {
    SQLiteDatabase sqldb = EGLifeStyleApplication.sqLiteDatabase;
    String Query = "Select * from " + TableName + " where " + dbfield + " = " + fieldValue;
    Cursor cursor = sqldb.rawQuery(Query, null);
        if(cursor.getCount() <= 0){
            cursor.close();
            return false;
        }
    cursor.close();
    return true;
}

I hope this is useful to you... This function returns true if record already exists in db. Otherwise returns false.

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