如何在 android 中的 SQLite 数据库中搜索？

Question

我正在制作一个用于存储联系人信息的数据库。因为我是android的新手，所以用了一段从网上找的代码。但是，它有错误，当运行它应用程序崩溃时。

这是数据库的代码：

存储操纵器

public class FriendStorage extends SQLiteOpenHelper {

public FriendStorage(Context context, String name, SQLiteDatabase.CursorFactory factory, int version){
    super(context, name, factory, version);
}

public static final String Database_name = "net.Friend.db";
public static final int Database_version = 1;

public static final String _ID = "_id";
public static final String Table_Friend = "Table_friend";
public static final String Username = "username";
public static final String PhoneNumber = "phoneNumber";

private static final String TABLE_FRIEND_CREATE =
        "CREATE TABLE " + Table_Friend
                + " (" + _ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                + Username + " VARCHAR(25), "
                + PhoneNumber + " VARCHAR(25)";

public static final String Table_Friend_Drop = "DROP TABLE IF EXISTS" + Table_Friend;

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(TABLE_FRIEND_CREATE);
}

public void insert(String username, String phoneNumber){
    long rowId;
    try {

        SQLiteDatabase db = getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(Username, username);
        contentValues.put(PhoneNumber, phoneNumber);
        rowId = db.insert(Table_Friend, null, contentValues);

    }catch (Exception e){
        e.printStackTrace();
    }
}

public Cursor get(){
    Cursor cursor;
    SQLiteDatabase db = getReadableDatabase();
    String selectQuery = "SELECT * FROM" + Table_Friend;
    cursor = db.rawQuery(selectQuery, null);
    return cursor;
}

public Cursor Update(String preUsername, String prePhoneNumber, String newUsername, String newPhoneNumber){
    Cursor cursor;
    SQLiteDatabase db = getWritableDatabase();
    String updateTable = "UPDATE" + Table_Friend + "SET" + Username + " = " + newUsername
            + "AND" + PhoneNumber + " = " + newPhoneNumber + "WHERE" + Username + " = "
            + preUsername + "AND" + PhoneNumber + " = " + prePhoneNumber;
    cursor = db.rawQuery(updateTable, null);
    return cursor;
}

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

}

并且在 Main Activity 中我使用 get 函数在数据库中搜索。

主要Activity

FriendStorage friendInfoStorage = new FriendStorage(this, "net.Friend.db", null, 1);
cursor = friendInfoStorage.get();
int noOfFriends = 0;
if (cursor.getCount() > 0) {
    cursor.moveToFirst();
    while ((!cursor.isAfterLast()) && (noOfFriends < cursor.getCount())) {
        if (noOfFriends == 0) {
            Myself.setUsername(cursor.getString(1));
            Myself.setPhone_Number(cursor.getString(2));
        } else {
            User.setUsername(cursor.getString(1));
            User.setPhone_Number(cursor.getString(2));
            Friends.add(User);
        }
        noOfFriends++;
        cursor.moveToNext();
    }
}
friendInfoStorage.close();

错误是这样的：

07-12 03:11:14.024 14157-14157/net.network.alire.clientchat E/AndroidRuntime: FATAL EXCEPTION: main
                                                                          Process: net.network.alire.clientchat, PID: 14157
                                                                          java.lang.RuntimeException: Unable to start activity ComponentInfo{net.network.alire.clientchat/net.network.alire.clientchat.MainActivity}: android.database.sqlite.SQLiteException: near ")": syntax error (code 1): , while compiling: CREATE TABLE Table_friend (_id INTEGER PRIMARY KEY AUTOINCREMENT, username VARCHAR(25), phoneNumber VARCHAR(25)
                                                                              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2329)
                                                                              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
                                                                              at android.app.ActivityThread.access0(ActivityThread.java:147)
                                                                              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296)
                                                                              at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                              at android.os.Looper.loop(Looper.java:135)
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                                              at java.lang.reflect.Method.invoke(Method.java:372)
                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
                                                                           Caused by: android.database.sqlite.SQLiteException: near ")": syntax error (code 1): , while compiling: CREATE TABLE Table_friend (_id INTEGER PRIMARY KEY AUTOINCREMENT, username VARCHAR(25), phoneNumber VARCHAR(25)
                                                                              at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
                                                                              at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:891)
                                                                              at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:502)
                                                                              at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
                                                                              at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
                                                                              at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
                                                                              at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
                                                                              at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1605)
                                                                              at net.network.alire.toolBox.FriendStorage.onCreate(FriendStorage.java:36)
                                                                              at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)
                                                                              at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:187)
                                                                              at net.network.alire.toolBox.FriendStorage.get(FriendStorage.java:56)
                                                                              at net.network.alire.clientchat.MainActivity.onCreate(MainActivity.java:52)
                                                                              at android.app.Activity.performCreate(Activity.java:5933)
                                                                              at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
                                                                              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2282)
                                                                              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389) 
                                                                              at android.app.ActivityThread.access0(ActivityThread.java:147) 
                                                                              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296) 
                                                                              at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                              at android.os.Looper.loop(Looper.java:135) 
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5254) 
                                                                              at java.lang.reflect.Method.invoke(Native Method) 
                                                                              at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898) 
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)

谁能告诉我代码有什么问题？

提前致谢

Answer 1

您的创建语句中缺少一个“)”字符。
你应该在 SQLite 中使用 TEXT 而不是 varchar。
你不应该使用 AUTOINCREMENT。它是在 PRIMARY KEY 中用 SQLite 隐式实现的。

如何在 android 中的 SQLite 数据库中搜索？

How to search in a SQLite database in android?

android

sqlite

sqliteopenhelper

存储操纵器

主要Activity