Question

我是Android Studio和数据库的初学者。但是，在视频和指南之后，我能够设置一个基本的。

这样做后，我想扩展它以创建2个额外的表。但是后来当我试图将数据输入到后面的表时，应用程序崩溃了，我似乎无法找到它的错误。我尝试了不同的格式化语法，但它在同一事件（当我尝试将数据提交到表）时不断崩溃。

 //Following is the DatabaseHelper class that set up the database. 
 public class DatabaseHelper extends SQLiteOpenHelper{

//contacts
private static final String TABLE_CONTACTS = "contacts";
private static final String COLUMN_ID = "id";
private static final String COLUMN_NAME = "name";
private static final String COLUMN_EMAIL = "email";
private static final String COLUMN_PHONENUMBER = "phonenumber";
private static final String COLUMN_UNAME = "uname";
private static final String COLUMN_PASS = "pass";

//inventory
private static final String TABLE_ORGANIZATIONS = "organizations";
private static final String COLUMN_ORGANIZATION_ITEMID = "itemid";
private static final String COLUMN_ORGANIZATION_ITEMNAME = "itemname";
private static final String COLUMN_ORGANIZATION_PRICE = "price";
private static final String COLUMN_ORGANIZATION_QUANTITY = "quantity";
private static final String COLUMN_ORGANIZATION_DESCRIPTION = "description";

//management
private static final String TABLE_MANAGEMENTS = "managements";
private static final String COLUMN_MANAGEMENT_EVENTID = "eventid";
private static final String COLUMN_MANAGEMENT_EVENTNAME = "eventname";
private static final String COLUMN_MANAGEMENT_EVENTDATE = "eventdate";


private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "inventstory.db";

//decare database variable
SQLiteDatabase db;

//create a table for to hold values.
private static final String TABLE_CREATE_CONTACTS = "create table " + TABLE_CONTACTS + "("
        + COLUMN_ID + " integer primary key, "
        + COLUMN_NAME + " text not null , "
        + COLUMN_EMAIL + " text not null , "
        + COLUMN_PHONENUMBER + " text not null , "
        + COLUMN_UNAME + " text not null , "
        + COLUMN_PASS + " text not null" + ");";

//create a table for to hold values.
private static final String TABLE_CREATE_ORGANIZATIONS = "create table " + TABLE_ORGANIZATIONS + "("
        + COLUMN_ORGANIZATION_ITEMID + " integer primary key autoincrement, "
        + COLUMN_ORGANIZATION_ITEMNAME + " text not null , "
        + COLUMN_ORGANIZATION_PRICE + " text not null , "
        + COLUMN_ORGANIZATION_QUANTITY + " text not null , "
        + COLUMN_ORGANIZATION_DESCRIPTION + " text not null " + ");";

//create a table for to hold values.
private static final String TABLE_CREATE_MANAGEMENTS = " create table " + TABLE_MANAGEMENTS + "("
        + COLUMN_MANAGEMENT_EVENTID + " integer primary key, "
        + COLUMN_MANAGEMENT_EVENTNAME + " text not null , "
        + COLUMN_MANAGEMENT_EVENTDATE + " text not null " + ");";

//constructor
public DatabaseHelper(Context context)
{
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

    public void insertOrganization(inventoryorg c){

    //to insert to the database, use 'getWrite...' to make connection
    db = this.getWritableDatabase();
    //create content values
    ContentValues values = new ContentValues();

    // '*' means everything
    // fetch the data


    String query = " select * from 'organizations' ";
    Cursor cursor = db.rawQuery(query, null);
    int count = cursor.getCount(); //what does this do

 //   values.put(COLUMN_ORGANIZATION_ITEMID, count); // should this be changed to 'c.getItemid()'
    values.put(COLUMN_ORGANIZATION_ITEMNAME, c.getItemname());
    values.put(COLUMN_ORGANIZATION_PRICE, c.getPrice());
    values.put(COLUMN_ORGANIZATION_QUANTITY, c.getQuantity());
    values.put(COLUMN_ORGANIZATION_DESCRIPTION, c.getDescription());

    db.insert(TABLE_ORGANIZATIONS, null, values);

}

  @Override
   public void onCreate(SQLiteDatabase db) {
  //change
    //db.execSQL(TABLE_CREATE_CONTACTS);
    //db.execSQL(TABLE_CREATE_ORGANIZATIONS);
    //db.execSQL(TABLE_CREATE_MANAGEMENTS);
    db.execSQL(TABLE_CREATE_CONTACTS+TABLE_CREATE_ORGANIZATIONS+TABLE_CREATE_MANAGEMENTS);
    this.db = db;
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//    db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
  //  db.execSQL("DROP TABLE IF EXISTS " + TABLE_ORGANIZATIONS);
    //db.execSQL("DROP TABLE IF EXISTS " + TABLE_MANAGEMENTS);
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS
            + " DROP TABLE IF EXISTS " + TABLE_ORGANIZATIONS
            + " DROP TABLE IF EXISTS " + TABLE_MANAGEMENTS); //same result
    this.onCreate(db);

}

以下代码是将数据插入表中的函数（来自OrgInsert.java）（在Databasehelper.java上为decalred）。

public void onClickOrgSubmitButton(View v){

    if(v.getId()==R.id.BSubmitButton){
        //we read data from signup
        EditText itemname = (EditText) findViewById(R.id.TFitemname);
        EditText price = (EditText) findViewById(R.id.TFprice);
        EditText quantity = (EditText) findViewById(R.id.TFquantity);
        EditText description = (EditText) findViewById(R.id.TFdescription);

        //convert them to string values
        String itemnamestr = itemname.getText().toString();
        String pricestr = price.getText().toString();
        String quantitystr = quantity.getText().toString();
        String descriptionstr = description.getText().toString();

        //insert to the database
        inventoryorg inv = new inventoryorg();
        inv.setItemname(itemnamestr);
        inv.setPrice(pricestr);
        inv.setQuantity(quantitystr);
        inv.setDescription(descriptionstr);

               //this one needs to be enforced.
        helper.insertOrganization(inv);

        //popup message.
        Toast pass = Toast.makeText(OrgInsert.this, "Successfully created.", Toast.LENGTH_LONG);
        pass.show();

        //'starting new activity.' To start, we need to make object of Intent class
        //This takes back to the 'Organization' after new data is inserted.
        Intent i = new Intent(OrgInsert.this, Organization.class);
        startActivity(i);
    }
}

引起：android.database.sqlite.SQLiteException：没有这样的表：组织（代码1）:,同时编译：select * from＆＃39; organization＆＃39;



表尚未创建   怀疑：＆＃39;计数＆＃39;来自value.put的ItemID

// java.lang.IllegalStateException：无法执行android的方法：onClick
  //
  // at com.example.edward.inventstoryreformat.OrgInsert.onSubmitButton（OrgInsert.java:51）

我认为：51是helper.insertOrganization(inv)。

以上信息是我尝试解决的一些错误消息。这让我很困惑，因为联系人＆＃39;创建没有任何问题，这是由＆＃39; SignUp.java＆＃39;完成的。我使用SQLite Manager检查了数据库，并验证了这些是否已创建和保存。

Answer 1

在 insertOrganization（）方法中，在SELECT语句中将＆nbsp;＆＃39; 更改为组织。

更新（2016/04/20）：

正如所承诺的，有关SQL语句中引号的一些信息：

[S]单引号用于SQL查询中的[S]文字。由于组织应该已经创建，因此它已经是数据库的表对象。因此，在这种情况下不使用单引号。

[D]双引号用于[D] atabase中的保留关键字。因此，如果您的表名为插入，则应使用 SELECT * FROM＆＃34; insert＆＃34; 。您可以尝试双引号，但它应该给出相同的错误。尽管如此，在引用数据库中的现有对象时，请不要使用单引号。

此外，在再次检查您的代码和更新后，我发现了一些您应该仔细检查的事项：

您的TABLE_CREATE_ORGANIZATIONS指出您的COLUMN_ORGANIZATION_ITEMID应自动递增。这意味着您不必为该表显式设置id列。因此，您在INSERT代码中根本不需要以下行，这实际上是当前的错误导致点：
```
String query = " select * from 'organizations' ";
Cursor cursor = db.rawQuery(query, null);
int count = cursor.getCount(); //what does this do
```
此外，请不要忘记在打开数据库后使用db.close（）关闭数据库。在这种情况下，它应该在insertOrganization（）的最后几行，onCreate（）和onUpdate（）方法
最后，在所有TABLE_CREATE_XXX字符串常量中，使用CREATE TABLE IF NOT EXISTS（...），以确保您没有覆盖任何内容。

如果有任何问题可以帮助我。如果它没有，我将为您提供一种扩展SQLiteOpenHelper类的不同方法。

Answer 2

试试这个!!

 public void insertOrganization(inventoryorg c){

//to insert to the database, use 'getWrite...' to make connection
db = this.getWritableDatabase();
//create content values
ContentValues values = new ContentValues();
 //   values.put(COLUMN_ORGANIZATION_ITEMID, count); // should this be changed to 'c.getItemid()'
values.put(COLUMN_ORGANIZATION_ITEMNAME, c.getItemname());
values.put(COLUMN_ORGANIZATION_PRICE, c.getPrice());
values.put(COLUMN_ORGANIZATION_QUANTITY, c.getQuantity());
values.put(COLUMN_ORGANIZATION_DESCRIPTION, c.getDescription());

db.insert(TABLE_ORGANIZATIONS, null, values);
db.close();

}

如何在Android中设置SQLite数据库？

2 个答案: