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Question

我使用Android Studio和SQLite构建App。如何将多个表组成一个数据库？

我为我的DataHelper编写了这段代码并且不确定它是对的。

echo "<script>
     $(window).load(function(){
         $('#mymodal').modal('show');
     });
</script>";

}

Answer 1

您的代码运行正常。我创建了简单的MainActivity来说明它 - 欢迎尝试一下。

package <your package>;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    private DataHelper databaseOpenHelper = null; // database helper
    private SQLiteDatabase database = null; // database object


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);


        databaseOpenHelper = new DataHelper(this);

        database = databaseOpenHelper.getWritableDatabase();


        Cursor cursor1 = database.query(
                "admin", //is the table
                null, //null for all colm
                null,//where
                null,//where argument for where placeholder's
                null,//group by
                null,//having
                null //ordered by
        );

        Cursor cursor2 = database.query(
                "user", //is the table
                null, //null for all colm
                null,//where
                null,//where argument for where placeholder's
                null,//group by
                null,//having
                null //ordered by
        );


        Integer iID = -1;
        String sID = "-1";
        String nAme = "kkk";
        String pSswd = "lll";

        while (cursor1.moveToNext()) {
            iID = cursor1.getInt(0);
            sID = iID.toString();
            nAme = cursor1.getString(1);
            pSswd = cursor1.getString(2);
            Log.i("Data from Table1:", sID + " " + nAme + " " + pSswd);
        }

        while (cursor2.moveToNext()) {
            iID = cursor2.getInt(0);
            sID = iID.toString();
            nAme = cursor2.getString(1);
            pSswd = cursor2.getString(2);
            Log.i("Data from Table2:", sID + " " + nAme + " " + pSswd);
        }
    }
}

输出打印：

09-24 08：39：30.575 9607-9607 /？ I /来自Table1 :: 1 Jana 1234的数据

09-24 08：39：30.576 9607-9607 /？ I /来自Table2 :: 1 Mudita 1234的数据

Answer 2

String sql = "create table [table1_name](id integer primary key,...);";
String sql2 = "create table [table2_name](id integer primary key,..);";
.
.
.
db.execSQL(sql);
db.execSQL(sql2);
.
.

执行多个Create Table Queries可以在一个数据库中创建多个表。

Answer 3

DatabaseHelper.java

public class DataHelper extends SQLiteOpenHelper {

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

static final String CREATE_TABLE_ADMIN = "create table " + "admin" + "( "
        + "ID" + "  integer primary key autoincrement," + "NAME text,"
        + "PASSWORD text); ";

static final String CREATE_TABLE_USER = "create table " + "user" + "( "
        + "ID" + "  integer primary key autoincrement," + "NAME text,"
        + "PASSWORD text); ";

public static SQLiteDatabase db;

public LoginDataBaseAdapter(Context context) {
    super(context, DATABASE_NAME, null,1);
}
@Override
public void onCreate(SQLiteDatabase _db) {
    _db.execSQL(CREATE_TABLE_ADMIN);
    _db.execSQL(CREATE_TABLE_USER);
}

@Override
public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion)       {
    onCreate(_db);
}


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

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

public void insertEntry_Admin(int id,String Name, String password) {

    ContentValues newValues = new ContentValues();
    newValues.put("ID",id);
    newValues.put("NAME", Name);
    newValues.put("PASSWORD", password);
    db.insert("admin", null, newValues);
}

public void insertEntry_User(int id,String Name, String password) {

    ContentValues newValues = new ContentValues();
    newValues.put("ID",id);
    newValues.put("NAME", Name);
    newValues.put("PASSWORD", password);
    db.insert("user", null, newValues);
}
}

将多个表组成一个数据库SQLite

3 个答案:

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