java - 在 Android 上使用 SQLite 触发器返回错误

标签 java android sqlite kotlin fts4

我是 SQLite 的新手，我正在尝试创建一个应用程序，用户可以在其中创建任务并向其附加提醒。我正在使用 SQLite 数据库来保存这些项目。一切正常，现在我想实现全文搜索功能，我已经阅读了 SQLite 文档，使用 FTS4 VIRTUAL TABLE 是一种比普通表更好的方法。

  • 所以为了保持虚拟表同步，我不得不使用触发器。但是在调用execSQL("//*Trigger code*//")
    • 后出现错误

这是我的触发器(按照文档中提到的相同顺序使用它们):

object SQLiteTriggerUtils {

    fun getBeforeDeleteTrigger(mainTable : String,
                               ftsTable : String,
                               rowId : Int?) : String {

        return "CREATE TRIGGER table_bd" +
                " BEFORE DELETE ON $mainTable" +
                " BEGIN DELETE FROM $ftsTable" +
                " WHERE docid=$rowId END;"
    }

    fun getBeforeUpdateTrigger(mainTable: String,
                               ftsTable: String,
                               rowId: Int?) : String {

        return "CREATE TRIGGER table_bu" +
                " BEFORE UPDATE ON $mainTable" +
                " BEGIN DELETE FROM $ftsTable" +
                " WHERE docid=$rowId END;"
    }

    fun getAfterUpdateTrigger(
        mainTable: String,
        ftsTable: String,
        rowId: Int?,
        updatedField: String,
        updatedValue: String?
    ) : String {

        return "CREATE TRIGGER table_au" +
                " AFTER UPDATE ON $mainTable" +
                " BEGIN INSERT INTO $ftsTable(docid, $updatedField)" +
                " VALUES($rowId, $updatedValue) END;"
    }

    fun getAfterInsertTrigger(
        mainTable: String,
        ftsTable: String,
        rowId: Int?,
        updatedField: String,
        updatedValue: String?
    ) : String {

        return "CREATE TRIGGER table_ai" +
                " AFTER INSERT ON $mainTable" +
                " BEGIN INSERT INTO $ftsTable(docid, $updatedField)" +
                " VALUES($rowId, $updatedValue) END;"
    }
}

这是我的数据库 onCreate() 方法:

override fun onCreate(db: SQLiteDatabase) {
        val CREATION_TABLE = ("CREATE TABLE $TABLE_NAME ( "
                + "$KEY_ID INTEGER PRIMARY KEY AUTOINCREMENT, "
                + "$KEY_LABEL TEXT, "
                + "$KEY_DESCRIPTION TEXT, "
                + "$KEY_IMPORTANCE INTEGER,"
                + "$KEY_LOGO INTEGER,"
                + "$KEY_TO_DO_DATE TEXT,"
                + "$KEY_CREATION_DATE TEXT)")
        val FTS_CREATION_TABLE = ("CREATE VIRTUAL TABLE $FTS_TABLE_NAME USING fts4 (content='$TABLE_NAME', $KEY_LABEL)")
        db.execSQL(CREATION_TABLE)
        db.execSQL(FTS_CREATION_TABLE)
    } 

override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        db.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
        db.execSQL("DROP TABLE IF EXISTS $FTS_TABLE_NAME")
        onCreate(db)
    }

执行触发器 onDeleteItem() 方法的示例:

override fun deleteItem(itemId: Int): Boolean {
        var success : Boolean
        writableDatabase.apply {
            execSQL(SQLiteTriggerUtils.getBeforeDeleteTrigger(TABLE_NAME, FTS_TABLE_NAME, itemId))
            success = delete(TABLE_NAME, "id = ?", arrayOf(itemId.toString())) > 0
            close()
        }
        return success
    }

返回错误 : 

android.database.sqlite.SQLiteException: near "END": syntax error (Sqlite code 1): , while compiling: CREATE TRIGGER table_bd BEFORE DELETE ON todo_tasks BEGIN DELETE FROM fts_todo_tasks WHERE docid=1 END;, (OS error - 2:No such file or directory)

最佳答案

我认为你的问题是在更正了遵循触发操作的语法错误之后，该操作是在 BEGIN 和 END 之间用分号编码的:-

enter image description here

可能是您在知道值之前尝试添加触发器(可能不是这样，具体取决于代码)。

触发器是一个实体，如 View 、表、索引等，它们构成了模式的一部分，因此需要一个唯一的名称。所以 CREATE TRIGGER the_trigger_name ...... 要求 the_trigger_name 是唯一的。似乎每次调用触发器的操作即将执行时，您可能都在尝试创建相同的触发器，然后由于触发器已经存在而失败。

您可以使用 CREATE TRIGGER IF NOT EXISTS the_trigger_name ......，但是将使用现有的触发器。

因此，您可能希望在创建触发器之前DROP TRIGGER the_trigger_name。

但是!

表示触发器的预期用途是在事件(UPDATE、DELETE 或 INSERT)发生时(实际上是紧接在之前或之后)自动执行类似的操作。因此，触发器可以访问导致触发器被操作(触发操作)的行的列。

如果触发操作是 INSERT，则可以使用 new.column 引用正在插入的行的列，并在触发操作(在 BEGIN 和 END 之间指定的操作)中使用。

如果触发操作是 DELETE，则 old.column 可用于引用被删除行的列。

如果触发 Action 是 UPDATE 那么 new.column 和 old.column 都可以被引用。

  • 其中 .column 被相应的列替换。

因此当 documentation说:-

Instead of writing separately to the full-text index and the content table, some users may wish to use database triggers to keep the full-text index up to date with respect to the set of documents stored in the content table. For example, using the tables from earlier examples:

CREATE TRIGGER t2_bu BEFORE UPDATE ON t2 BEGIN
  DELETE FROM t3 WHERE docid=old.rowid;
END;
CREATE TRIGGER t2_bd BEFORE DELETE ON t2 BEGIN
  DELETE FROM t3 WHERE docid=old.rowid;
END;

CREATE TRIGGER t2_au AFTER UPDATE ON t2 BEGIN
  INSERT INTO t3(docid, b, c) VALUES(new.rowid, new.b, new.c);
END;
CREATE TRIGGER t2_ai AFTER INSERT ON t2 BEGIN
  INSERT INTO t3(docid, b, c) VALUES(new.rowid, new.b, new.c);
END;

你会看到它使用了old.docid和new.rowid

因此，old.docid 将是被删除更新的行的 docid，而 new.rowid 将是被插入到 $TABLE_NAME 中的行的 rowid。因此，每个触发器只需要定义一次，因为它是通用的。

因此我相信您可以使用:-

val TRG_BD = "trigger_bd" //<<<<<<<<<< ADDED >>>>>>>>>>
val TRG_BU = "trigger_bu" //<<<<<<<<<< ADDED >>>>>>>>>>
val TRG_AU = "trigger_au" //<<<<<<<<<< ADDED >>>>>>>>>>
val TRG_AI = "trigger_ai" //<<<<<<<<<< ADDED >>>>>>>>>>

override fun onCreate(db: SQLiteDatabase) {
    val CREATION_TABLE = ("CREATE TABLE $TABLE_NAME ( "
            + "$KEY_ID INTEGER PRIMARY KEY AUTOINCREMENT, "
            + "$KEY_LABEL TEXT, "
            + "$KEY_DESCRIPTION TEXT, "
            + "$KEY_IMPORTANCE INTEGER,"
            + "$KEY_LOGO INTEGER,"
            + "$KEY_TO_DO_DATE TEXT,"
            + "$KEY_CREATION_DATE TEXT)")
    val FTS_CREATION_TABLE = ("CREATE VIRTUAL TABLE $FTS_TABLE_NAME USING fts4 (content='$TABLE_NAME', $KEY_LABEL)")

    //<<<<<<<<<< ADDED FOLLOWING LINES  >>>>>>>>
    val BD_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_BD " +
            "BEFORE DELETE ON $TABLE_NAME " +
            "BEGIN " +
            "DELETE FROM $FTS_TABLE_NAME " +
            "WHERE docid=old.rowid; " +
            "END;")
    val BU_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_BU " +
            "BEFORE UPDATE ON $TABLE_NAME " +
            "BEGIN " +
            "DELETE FROM $FTS_TABLE_NAME " +
            "WHERE docid=old.rowid; " +
            "END;")
    val AU_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_AU " +
            "AFTER UPDATE ON $TABLE_NAME " +
            "BEGIN " +
            "INSERT INTO $FTS_TABLE_NAME (docid, $KEY_LABEL) VALUES(new.$KEY_ID,new.$KEY_LABEL); " + //<<<<<<<< not sure $KEY_LABEL is correct column
            "END;")
    val AI_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_AI " +
            "AFTER INSERT ON $TABLE_NAME " +
            "BEGIN " +
            "INSERT INTO $FTS_TABLE_NAME (docid, $KEY_LABEL) VALUES(new.$KEY_ID,new.$KEY_LABEL); " +
            "END;")
    //<<<<<<<<<< END OF ADDED LINES >>>>>>>>


    db.execSQL(CREATION_TABLE)
    db.execSQL(FTS_CREATION_TABLE)
    db.execSQL(BD_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
    db.execSQL(BU_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
    db.execSQL(AU_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
    db.execSQL(AI_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
}

override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
    db.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
    db.execSQL("DROP TABLE IF EXISTS $FTS_TABLE_NAME")
    db.execSQL("DROP TRIGGER IF EXISTS $TRG_BD") //<<<<<<<<<< ADDDED >>>>>>>>
    db.execSQL("DROP TRIGGER IF EXISTS $TRG_BU") //<<<<<<<<<< ADDDED >>>>>>>>
    db.execSQL("DROP TRIGGER IF EXISTS $TRG_AU") //<<<<<<<<<< ADDDED >>>>>>>>
    db.execSQL("DROP TRIGGER If EXISTS $TRG_AI") //<<<<<<<<<< ADDDED >>>>>>>>
    onCreate(db)
}

以上将替换(即不需要以下):-

object SQLiteTriggerUtils {

    fun getBeforeDeleteTrigger(mainTable : String,
                               ftsTable : String,
                               rowId : Int?) : String {

        return "CREATE TRIGGER table_bd" +
                " BEFORE DELETE ON $mainTable" +
                " BEGIN DELETE FROM $ftsTable" +
                " WHERE docid=$rowId END;"
    }

    fun getBeforeUpdateTrigger(mainTable: String,
                               ftsTable: String,
                               rowId: Int?) : String {

        return "CREATE TRIGGER table_bu" +
                " BEFORE UPDATE ON $mainTable" +
                " BEGIN DELETE FROM $ftsTable" +
                " WHERE docid=$rowId END;"
    }

    fun getAfterUpdateTrigger(
        mainTable: String,
        ftsTable: String,
        rowId: Int?,
        updatedField: String,
        updatedValue: String?
    ) : String {

        return "CREATE TRIGGER table_au" +
                " AFTER UPDATE ON $mainTable" +
                " BEGIN INSERT INTO $ftsTable(docid, $updatedField)" +
                " VALUES($rowId, $updatedValue) END;"
    }

    fun getAfterInsertTrigger(
        mainTable: String,
        ftsTable: String,
        rowId: Int?,
        updatedField: String,
        updatedValue: String?
    ) : String {

        return "CREATE TRIGGER table_ai" +
                " AFTER INSERT ON $mainTable" +
                " BEGIN INSERT INTO $ftsTable(docid, $updatedField)" +
                " VALUES($rowId, $updatedValue) END;"
    }
}

此外，TRIGGERS 会自动运行

override fun deleteItem(itemId: Int): Boolean {
        var success : Boolean
        writableDatabase.apply {
            execSQL(SQLiteTriggerUtils.getBeforeDeleteTrigger(TABLE_NAME, FTS_TABLE_NAME, itemId))
            success = delete(TABLE_NAME, "id = ?", arrayOf(itemId.toString())) > 0
            close()
        }
        return success
    }

可以替换为(其他的也一样):-

override fun deleteItem(itemId: Int): Boolean {
        var success : Boolean
        writableDatabase.apply {
            success = delete(TABLE_NAME, "id = ?", arrayOf(itemId.toString())) > 0
            close()
        }
        return success
    }

注意 以上是原理代码，尚未经过测试或运行。因此它可能包含错误。

  • 我还建议触发器名称，而不是使用 au(更新后)，使用更具描述性的名称，因此命名约定没有那么严格(例如，你想使用另一个更新后触发器？)。<

工作示例

以下是一个演示触发器的工作示例(注意 Kotlin 经验不足，因此代码可能不是最好的)

数据库助手.kt

val DB_VERSION = 1;
val DB_NAME = "mydb"

public class DatabaseHelper(context: Context?) :

    SQLiteOpenHelper(context, DB_NAME, null, DB_VERSION) {

    val TABLE_NAME = "mytable"
    val FTS_TABLE_NAME = "myftstable"
    val TRG_BD = "trigger_bd"
    val TRG_BU = "trigger_bu"
    val TRG_AU = "trigger_au"
    val TRG_AI = "trigger_ai"
    val KEY_ID = "id";
    val KEY_LABEL = "label"
    val KEY_DESCRIPTION = "desctription"
    val KEY_IMPORTANCE = "importance";
    val KEY_LOGO = "logo";
    val KEY_TO_DO_DATE = "todo_date"
    val KEY_CREATION_DATE = "creation_date"



    override fun onCreate(db: SQLiteDatabase) {
        val CREATION_TABLE = ("CREATE TABLE $TABLE_NAME ( "
                + "$KEY_ID INTEGER PRIMARY KEY AUTOINCREMENT, "
                + "$KEY_LABEL TEXT, "
                + "$KEY_DESCRIPTION TEXT, "
                + "$KEY_IMPORTANCE INTEGER,"
                + "$KEY_LOGO INTEGER,"
                + "$KEY_TO_DO_DATE TEXT,"
                + "$KEY_CREATION_DATE TEXT)")
        val FTS_CREATION_TABLE = ("CREATE VIRTUAL TABLE $FTS_TABLE_NAME USING fts4 (content='$TABLE_NAME', $KEY_LABEL)")

        //<<<<<<<<<< ADDED FOLLOWING LINES  >>>>>>>>
        val BD_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_BD " +
                "BEFORE DELETE ON $TABLE_NAME " +
                "BEGIN " +
                "DELETE FROM $FTS_TABLE_NAME " +
                "WHERE docid=old.$KEY_ID; " +
                "END;")
        val BU_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_BU " +
                "BEFORE UPDATE ON $TABLE_NAME " +
                "BEGIN " +
                "DELETE FROM $FTS_TABLE_NAME " +
                "WHERE docid=old.$KEY_ID; " +
                "END;")
        val AU_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_AU " +
                "AFTER UPDATE ON $TABLE_NAME " +
                "BEGIN " +
                "INSERT INTO $FTS_TABLE_NAME (docid, $KEY_LABEL) VALUES(new.$KEY_ID,new.$KEY_LABEL); " + //<<<<<<<< not sure $KEY_LABEL is correct column
                "END;")
        val AI_CREATION_TRIGGER = ("CREATE TRIGGER IF NOT EXISTS $TRG_AI " +
                "AFTER INSERT ON $TABLE_NAME " +
                "BEGIN " +
                "INSERT INTO $FTS_TABLE_NAME (docid, $KEY_LABEL) VALUES(new.$KEY_ID,new.$KEY_LABEL); " +
                "END;")
        db.execSQL(CREATION_TABLE)
        db.execSQL(FTS_CREATION_TABLE)
        db.execSQL(BD_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
        db.execSQL(BU_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
        db.execSQL(AU_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
        db.execSQL(AI_CREATION_TRIGGER) //<<<<<<<<<< ADDED >>>>>>>>>>
    }

    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        db.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
        db.execSQL("DROP TABLE IF EXISTS $FTS_TABLE_NAME")
        db.execSQL("DROP TRIGGER IF EXISTS $TRG_BD") //<<<<<<<<<< ADDDED >>>>>>>>
        db.execSQL("DROP TRIGGER IF EXISTS $TRG_BU") //<<<<<<<<<< ADDDED >>>>>>>>
        db.execSQL("DROP TRIGGER IF EXISTS $TRG_AU") //<<<<<<<<<< ADDDED >>>>>>>>
        db.execSQL("DROP TRIGGER If EXISTS $TRG_AI") //<<<<<<<<<< ADDDED >>>>>>>>
        onCreate(db)
    }

    fun insert(label: String, description: String, importance: Int, tododate: String, creationdate: String ) {

        val cv = ContentValues()
        cv.put(KEY_LABEL,label)
        cv.put(KEY_DESCRIPTION,description)
        cv.put(KEY_IMPORTANCE,importance)
        cv.put(KEY_LOGO,0)
        cv.put(KEY_TO_DO_DATE,tododate)
        cv.put(KEY_CREATION_DATE,creationdate)

        val db = this.writableDatabase
        val inserted = db.insert(TABLE_NAME, null, cv )
        Log.d("INSERT","INSERT result in an id of " + inserted + ".")
    }

    fun update(id: Long, label: String) {
        val cv = ContentValues()
        cv.put(KEY_LABEL,label)

        val db = this.writableDatabase
        val updated = db.update(TABLE_NAME,cv,"$KEY_ID =" + id,null)
        Log.d("UPDATED","UPDATE resulted in " + updated + " rows being updated.")
    }

    fun delete(id: Long) {
        val whereclause = "$KEY_ID=" + id

        val db = this.writableDatabase
        val deleted = db.delete(TABLE_NAME,whereclause,null)
        Log.d("DELETED","DELETE resulted in " + deleted + " rows being deleted.")
    }

    fun logtables() {
        val db = this.writableDatabase
        val csr1 = db.query(TABLE_NAME, null, null, null, null, null, null)
        dumpCursor(csr1)
        val csr2 = db.query(FTS_TABLE_NAME,null,null,null,null,null,null)
        dumpCursor(csr2)
        csr1.close()
        csr2.close()
    }
}

主 Activity .kt

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val dbhelper = DatabaseHelper(this)
        dbhelper.insert("TEST001","Just Testing",10,"2019-01-01","2019-01-01")
        dbhelper.logtables()
        dbhelper.update(1,"001TEST")
        dbhelper.logtables()
        dbhelper.delete(1)
        dbhelper.logtables()
    }
}

结果(日志)

04-28 14:35:21.002 17810-17810/s.e.myapplication D/INSERT: INSERT result in an id of 1.
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@11697ce
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: 0 {
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    id=1
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    label=TEST001
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    desctription=Just Testing
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    importance=10
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    logo=0
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    todo_date=2019-01-01
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    creation_date=2019-01-01
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: }
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: <<<<<
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@3396ef
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out: 0 {
04-28 14:35:21.002 17810-17810/s.e.myapplication I/System.out:    label=TEST001
04-28 14:35:21.003 17810-17810/s.e.myapplication I/System.out: }
04-28 14:35:21.003 17810-17810/s.e.myapplication I/System.out: <<<<<

即FTS 已为 TEST001 插入一行

04-28 14:35:21.007 17810-17810/s.e.myapplication D/UPDATED: UPDATE resulted in 1 rows being updated.
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@9ce45fc
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out: 0 {
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    id=1
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    label=001TEST
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    desctription=Just Testing
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    importance=10
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    logo=0
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    todo_date=2019-01-01
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out:    creation_date=2019-01-01
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out: }
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out: <<<<<
04-28 14:35:21.007 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@30ec485
04-28 14:35:21.008 17810-17810/s.e.myapplication I/System.out: 0 {
04-28 14:35:21.008 17810-17810/s.e.myapplication I/System.out:    label=001TEST
04-28 14:35:21.008 17810-17810/s.e.myapplication I/System.out: }
04-28 14:35:21.008 17810-17810/s.e.myapplication I/System.out: <<<<<

即FTS 表已更新以反射(reflect) TEST001 已更改为 001TEST

04-28 14:35:21.011 17810-17810/s.e.myapplication D/DELETED: DELETE resulted in 1 rows being deleted.
04-28 14:35:21.011 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@10862da
04-28 14:35:21.011 17810-17810/s.e.myapplication I/System.out: <<<<<
04-28 14:35:21.011 17810-17810/s.e.myapplication I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@d4cb30b
04-28 14:35:21.011 17810-17810/s.e.myapplication I/System.out: <<<<<

非fts表删除后均为空

关于java - 在 Android 上使用 SQLite 触发器返回错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55881239/

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