Question

我试图弄清楚如何在点击按钮时删除整个表格让我说我有一个名为删除的按钮我想按下它并删除表格中的所有内容。我试过这个，但它没有用，我没有知道要放在按钮

void deleteAll()
{
    SQLiteDatabase db= ourHelper.getWritableDatabase();
    db.delete(DATABASE_TABLE, null, null);
}

代码：

package f.s.l;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class HotOrNot {
public static final String KEY_ROWID ="_id";
public static final String KEY_NAME ="persons_name";
public static final String KEY_HOTNESS ="persons_hotness";

private static final String DATABASE_NAME ="HotOrNotdb";
private static final String DATABASE_TABLE ="peopleTable";
private static final int DATABASE_VERSION =1;

private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;

private static class DbHelper extends SQLiteOpenHelper{

public DbHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    // TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
        KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
        KEY_NAME + " TEXT NOT NULL, " +
        KEY_HOTNESS + " TEXT NOT NULL);"
    );
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
    onCreate(db);
}
}

public HotOrNot(Context c){
    ourContext =c;
}

public HotOrNot open() throws SQLException {
    ourHelper = new DbHelper(ourContext);
    ourDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close(){
    ourHelper.close();
}

public long createEntry(String name, String hotness) {
    // TODO Auto-generated method stub
    ContentValues cv = new ContentValues();
    cv.put(KEY_NAME, name);
    cv.put(KEY_HOTNESS, hotness);
    return ourDatabase.insert(DATABASE_TABLE, null, cv);
}

public String getData() {
    // TODO Auto-generated method stub
    String [] columns = new String[]{ KEY_ROWID, KEY_NAME, KEY_HOTNESS};
    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ROWID);
    int iName = c.getColumnIndex(KEY_NAME);
    int iHotness = c.getColumnIndex(KEY_HOTNESS);

    for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
        result = result + c.getString(iRow) + " "+ c.getString(iName) + " " + c.getString(iHotness) + "\n";
}

return result;
}

}

Answer 1

你可以做到

db.execSQL("DELETE * FROM " + DATABASE_TABLE);

这不会删除表，但会删除表中的所有行。

Answer 2

尝试使用drop table命令，我认为它必须是drop table

如何删除表sql中的所有内容

2 个答案: