为什么我收到表名的列不存在错误 [英] Why am i getting a column doesnt exist error with the name of the table
问题描述
大家好，我正在尝试检索我在之前的活动中插入到数据库中的一些数据.这是我检索数据的代码
Hi guys Im trying to retrieve some data I inserted into a database in a previous activity. This is my code to Retrieve the data
public class Display_data extends AppCompatActivity {
ArrayList<String> Displist = new ArrayList<String>();
ListView no_name;
String db_Name;
TextView namer;
TextView Starter;
TextView Ender;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_data);
Bundle bundle = getIntent().getExtras();
no_name = (ListView) findViewById(R.id.Disp_list);
String message = bundle.getString("package");
String parameter;
SQLiteDatabase db = openOrCreateDatabase(message, SQLiteDatabase.CREATE_IF_NECESSARY, null);
SQLiteDatabase db1 = openOrCreateDatabase("Train_list.db", SQLiteDatabase.CREATE_IF_NECESSARY, null);
Cursor header;
namer=(TextView)findViewById(R.id.T1);
try {
header = db1.rawQuery("Select Train_name From Train_list Where Train_no="+message.substring(0,(message.length()-3)), null);
header.moveToFirst();
String temp = header.getString((header.getColumnIndex("Train_name")));
Toast.makeText(Display_data.this, "blahhh:"+temp, Toast.LENGTH_LONG).show();
Log.d("Sucess!","temp:"+temp);
Toast.makeText(Display_data.this, "Gotcha:"+temp , Toast.LENGTH_LONG).show();
namer.setText("Train Name: " + temp);
}catch(Exception e)
{
Log.d("Final Error",e.toString());
Toast.makeText(Display_data.this, "Error", Toast.LENGTH_LONG).show();
}
db_Name=message.substring(0,(message.length()-3));
try{
Cursor data_fetch = db.rawQuery("Select Stops From "+db_Name, null);
while (data_fetch.moveToNext()) {
String name = data_fetch.getString(data_fetch.getColumnIndex("Stops"));
if(Displist.contains(name)) {
}
else {
Displist.add(name);
//Toast.makeText(Display_data.this, "Added :"+name, Toast.LENGTH_SHORT).show();
}
}
data_fetch.close();
}catch (Exception e)
{
Toast.makeText(Display_data.this, "Yeah"+e.toString(), Toast.LENGTH_LONG).show();
Log.d("Damn Why",e.toString());
}
try {
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
this, android.R.layout.simple_list_item_1,Displist);
no_name.setAdapter(arrayAdapter);
}catch (Exception e){
Log.d("Display data error ",e.toString());
Toast.makeText(Display_data.this, "Listview Error" , Toast.LENGTH_LONG).show();
}
}
}
我注意到该部分
try {
header = db1.rawQuery("Select Train_name From Train_list Where Train_no="+message.substring(0,(message.length()-3)), null);
header.moveToFirst();
String temp = header.getString((header.getColumnIndex("Train_name")));
Toast.makeText(Display_data.this, "blahhh:"+temp, Toast.LENGTH_LONG).show();
Log.d("Sucess!","temp:"+temp);
Toast.makeText(Display_data.this, "Gotcha:"+temp , Toast.LENGTH_LONG).show();
namer.setText("Train Name: " + temp);
}catch(Exception e)
{
Log.d("Final Error",e.toString());
Toast.makeText(Display_data.this, "Error", Toast.LENGTH_LONG).show();
}
返回错误
D/Final Error: android.database.sqlite.SQLiteException: no such column: aa1000 (code 1): , while compiling: Select Train_name From Train_list Where Train_no=aa1000
我真的不明白这个错误，因为'aa1000'被插入到数据库中.
I really don't understand this error as 'aa1000' was inserted into the database.
这是数据库'train_list'的定义
This is the definition for the database 'train_list'
SQLiteDatabase db = openOrCreateDatabase( "Train_list.db", SQLiteDatabase.CREATE_IF_NECESSARY , null);
try {
final String CREATE_TABLE_TRAIN_LIST = "CREATE TABLE IF NOT EXISTS Train_list ("
+ "Train_name VARCHAR,"
+ "Train_no VARCHAR,"
+ "Train_start VARCHAR,"
+ "Train_end VARCHAR,"
+ "Seats_Available VARCHAR);";
db.execSQL(CREATE_TABLE_TRAIN_LIST);
Toast.makeText(admin_manipulation.this, "Table created", Toast.LENGTH_LONG).show();
String sql = "INSERT or replace INTO Train_list (Train_name, Train_no, Train_start, Train_end, Seats_Available) VALUES('"+str_Train_name + "',' " +str_Train_no + "', '" +str_Train_start+"','" +str_Train_end+"',' " +str_Train_seats +"');";
try {
db.execSQL(sql);
Toast.makeText(admin_manipulation.this, "train no:"+str_Train_no, Toast.LENGTH_SHORT).show();
}catch(Exception e)
{
Toast.makeText(admin_manipulation.this, "Sorry Not Inserted Sucessfully", Toast.LENGTH_SHORT).show();
Log.d("Error experienced",e.toString());
}
我检查了 Android Monitor 页面，没有发现提示aa1000"尚未插入数据库的错误.
I Checked the Android Monitor page and i did not find an error to suggest that "aa1000" had not been inserted into the database.
请注意，当只插入Train_name 和Train_no 时，其余都为空.
Please Do note that When inserting only Train_name and Train_no Were filled in the rest were left as null.
任何帮助将不胜感激！
推荐答案
将 aa1000 放入单引号 ('aa1000'):
Put aa1000 into single quotes ('aa1000'):
您的 SQL 查询应如下所示:
Your SQL query should look like:
Select Train_name From Train_list Where Train_no='aa1000'
因此在 db.rawQuery 中修改您的选择字符串:
So modify your select string inside db.rawQuery:
"Select Train_name From Train_list Where Train_no='"+message.substring(0,(message.length()-3))+"'";
但是不建议使用 rawQuery 进行选择查询并以这种方式传递参数，最好学习使用 query 方法
However it is not advised to use rawQuery for select queries and passing parameters this way, better learn use the query method
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