Question

我有一个框来写我的帐户名称我有一个按钮＆amp;当我在盒子里写的时候我想要按下按钮检查sqlite中是否存在帐户名称我想在将其发送到数据库之前检查它是否存在该帐户这是我想要帮助的代码

上课

prettier

file java

    package com.example.java.beta;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;



public class accounts extends SQLiteOpenHelper{

    public accounts(Context context)
    {
        super(context, "accounts.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table users(username varchar(30),password varchar(30))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

Answer 1

您可以使用以下代码检查数据库中是否存在记录：

accounts call = new accounts(register.this);
SQLiteDatabase create = call.getWritableDatabase();
String Query = "Select * from " + users + " where " + username + " = " + ed_username.getText();
Cursor cursor = create.rawQuery(Query, null);
    if(cursor.getCount() <= 0){
        create.execSQL("insert into users values(?,?)",
                    new String [] {ed_username.getText().toString(),ed_password.getText().toString()});
    }
cursor.close();

如何在SQLite中验证帐户名是否存在

1 个答案: