Question

所以我在phpMyAdmin中看到了很多触发器示例，但语法对我来说没有意义......我太过于简单了。

我想在phpMyAdmin上创建一个约束。我有两个表，一个是基金，一个是Fund_Shares_Purchased。在基金中，有一个属性“total_available”，它是可以购买的股票总数。在Fund_Shares_Purchased中，有一个属性“quantity”，即某人已购买的股票数量。这两个表与“Fund_Name”属性相关。

我尝试了以下内容......

CREATE TRIGGER limitFundShares
BEFORE INSERT ON Fund_Shares_Purchased
BEGIN
    IF (Fund.total_shares < NEW.quantity)
    THEN
        RAISERROR("You can't buy that many shares of the fund!")
    END IF;
END;

非常感谢任何帮助或指导！

Answer 1

以下是使用MySQL命令行客户端的测试示例：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.tab_fragment_1, container, false);
}

    @SuppressLint("WrongViewCast")
    @Override
    public void onStart() {
            super.onStart();

        ParseUser currentUser = ParseUser.getCurrentUser();

        String struser = currentUser.getUsername().toString();
        iv = (ImageView) getView().findViewById(R.id.imageView1);

        button1 = (Button) getView().findViewById(R.id.button1);
        button1.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent i = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                startActivityForResult(i, SELECTED_PICTURE);
            }


        });
        TextView txtUser = (TextView) getView().findViewById(R.id.txtuser);
        txtUser.setText(struser);

            logout = (Button) getView().findViewById(R.id.Logout);

            logout.setOnClickListener(new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(v.getContext());                            // set title
                        alertDialogBuilder.setTitle("Logout!");

                        // set dialog message
                        alertDialogBuilder
                                .setMessage("Do you want to logout with your account ? ")
                                .setCancelable(false)
                                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        ConnectivityManager cManager = (ConnectivityManager) getActivity()
                                                .getSystemService(Context.CONNECTIVITY_SERVICE);
                                        NetworkInfo nInfo = cManager.getActiveNetworkInfo();
                                        if (nInfo != null && nInfo.isConnected()) {

                                            ParseUser.logOut();
                                            getActivity().finish();

                                        } else {

                                            Toast.makeText(getActivity().getApplicationContext(),
                                                    "Check your internet connection", Toast.LENGTH_LONG).show();


                                        }
                                    }
                                })
                                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        // if this button is clicked, just close
                                        // the dialog box and do nothing
                                        dialog.cancel();
                                    }
                                });

                        // create alert dialog
                        AlertDialog alertDialog = alertDialogBuilder.create();

                        // show it
                        alertDialog.show();

                    }
            });

    }


@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {

    super.onActivityResult(requestCode,resultCode, data);
    switch (requestCode){
        case SELECTED_PICTURE :
            if (requestCode == SELECTED_PICTURE && resultCode == Activity.RESULT_OK){
                Uri uri = data.getData();
                String[]projection={MediaStore.Images.Media.DATA};
                Cursor cursor=getActivity().getContentResolver().query(uri, projection, null, null, null);
                cursor.moveToFirst();

                int  columnIndex=cursor.getColumnIndex(projection[0]);
                String filePath = cursor.getString(columnIndex);
                cursor.close();

                Bitmap YourSelectedImage= BitmapFactory.decodeFile(filePath);
                Drawable d=new BitmapDrawable(YourSelectedImage);
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                    iv.setImageURI(Uri.parse(filePath));

                }


            }
            break;
            default:
                break;
    }
}
  }

你应该能够将触发器创建语句粘贴到phpMyAdmin中，尽管我还没有测试过。

在phpMyAdmin中将约束创建为触发器

1 个答案: