java – 如何在sqlite中的数据库中添加第二个表？

发布时间：2020-12-15 02:01:53 所属栏目：Java 来源：网络整理

导读：我有数据库考试指南,我已经创建了一个表table_subject和现在我想在这个数据库中创建第二个表(table_chapter).我的问题是如何在现有数据库中添加此表？我有以下代码.任何帮助赞赏. private static final String DATABASE_CREATE = "create table IF NOT EXIS

我有数据库考试指南,我已经创建了一个表table_subject和现在
我想在这个数据库中创建第二个表(table_chapter).我的问题是如何在现有数据库中添加此表？我有以下代码.任何帮助赞赏.

private static final String DATABASE_CREATE = "create table IF NOT EXISTS "
        + TABLE_SUBJECT + "( " + COLUMN_ID
        + " integer primary key autoincrement," 
        + COLUMN_SUBJECT + " text not null,"
        + COLUMN_CHAPTER + " text,"
        + COLUMN_QUESTION + " text not null,"
        + COLUMN_OPTIONA + " text not null,"
        + COLUMN_OPTIONB + " text not null,"
        + COLUMN_OPTIONC + " text not null,"
        + COLUMN_OPTIOND + " text not null,"
        + COLUMN_CORRECT + " text not null,"
        + COLUMN_CONFIRM + " text not null);";

    private static final String DATABASE_CREATE1 = "create table IF NOT EXISTS "
    + TABLE_CHAPTER + "( " + COLUMN_ID
    + " integer primary key autoincrement," 
    + COLUMN_SUBJECT + " text not null,"
    + COLUMN_CHAPTER + " text,"
    + COLUMN_QUESTION + " text not null,"
    + COLUMN_OPTIONA + " text not null,"
    + COLUMN_OPTIONB + " text not null,"
    + COLUMN_OPTIONC + " text not null,"
    + COLUMN_OPTIOND + " text not null,"
    + COLUMN_CORRECT + " text not null,"
    + COLUMN_CONFIRM + " text not null);";

public MySQLiteHelper open() throws SQLException 
{
    db = this.getWritableDatabase();
    return this;
}

public MySQLiteHelper(Context context)
{
    super(context,DATABASE_NAME,null,DATABASE_VERSION);

}


@Override
public void onCreate(SQLiteDatabase database) {

    database.execSQL(DATABASE_CREATE);
    database.execSQL(DATABASE_CREATE1);

}

此代码不会创建第二个表.我想在我的数据库中使用这两个表.
它在logcat中显示以下错误.

03-21 18:31:06.551: ERROR/Database(8255): Error inserting chapter=paging correctoption=shadow copy craete a duplicate copy of page subject=operating system question=what is shadow copy? optiona=shadow copy craete a duplicate copy of page confirm=YES optionb=sahdow copy create paging  optionc=shadow copy delete duplicate page optiond=shadow copy delete original and create shadow copy
03-21 18:31:06.551: ERROR/Database(8255): android.database.sqlite.SQLiteException: no such table: chapter:,while compiling: INSERT INTO chapter(chapter,correctoption,subject,question,optiona,confirm,optionb,optionc,optiond) VALUES(?,?,?);
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:92)
03-21 18:31:06.551: ERROR/Database(8255):     at   android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:65)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:83)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:41)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteDatabase.compileStatement(SQLiteDatabase.java:1149)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1569)
03-21 18:31:06.551: ERROR/Database(8255):     at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1426)
03-21 18:31:06.551: ERROR/Database(8255):     at com.example.examguide.MySQLiteHelper.insertChapterData(MySQLiteHelper.java:212)
03-21 18:31:06.551: ERROR/Database(8255):     at com.example.examguide.ObjectiveAddActivity$2.onClick(ObjectiveAddActivity.java:155)

解决方法

创建另一个CREATE TABLE String,然后在onCreate中再次调用execSQL：

database.execSQL(DATABASE_CREATE1);
database.execSQL(DATABASE_CREATE2);

编辑

要将另一个表添加到现有数据库,请按如下所示修改onUpgrade方法.每当需要升级数据库时都会调用onUpgrade;请注意,您必须增加VERSION_NUMBER(您希望将其包含在类中的私有实例变量中)才能使其生效.

@Override
public void onUpgrade (SQLiteDatabase db,int oldVersion,int newVersion) {
    db.executeSQL(DATABASE_CREATE2);
}

（编辑：李大同）

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