java - 如何在android中的sqlite中使用波斯变量？

Question

我在 android sqlite 中创建表。我的表是类别:

db.execSQL("CREATE TABLE IF NOT EXISTS category (id_category INTEGER PRIMARY KEY AUTOINCREMENT,sub INT(5),name VARCHAR ,father INT(5), income_bool INT(1));");

现在我创建一个变量:

String a="بنزین"

我成功插入一行(带有波斯语名称)并在 ListView 中显示；

> But when i select i have errors: String ROW3 = "SELECT * FROM category
> WHERE name=" + a; 
>Cursor cursor = db.rawQuery(ROW3, null);
>cursor.moveToFirst();
>Log.d("ghable vorod be for", "sa");
>for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext())
        {
            Log.d("ghable vorod be for1", "sa");
            cat_id=(cursor.getColumnIndex("id_category"));
            Log.d("ghable vorod be for2", "sa");
        }

但是我在 logcat 中有这个错误:

sqlite returned: error code = 1, msg = no such column: بنزین

Shutting down VM

thread exiting with uncaught exception (group=0x40015560) E/AndroidRuntime(28713): FATAL EXCEPTION: main

android.database.sqlite.SQLiteException: no such column: بنزین: , while compiling: SELECT * FROM category WHERE name=بنزین

09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:92) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteCompiledSql.(SQLiteCompiledSql.java:65) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:83) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteQuery.(SQLiteQuery.java:49) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:42) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1356) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1324) 09-30 15:28:17.358: E/AndroidRuntime(28713): at com.example.hesabdar.New_income.onClick(New_income.java:174) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.view.View.performClick(View.java:2485) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.view.View$PerformClick.run(View.java:9080) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.os.Handler.handleCallback(Handler.java:587) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.os.Handler.dispatchMessage(Handler.java:92) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.os.Looper.loop(Looper.java:123) 09-30 15:28:17.358: E/AndroidRuntime(28713): at android.app.ActivityThread.main(ActivityThread.java:3683) 09-30 15:28:17.358: E/AndroidRuntime(28713): at java.lang.reflect.Method.invokeNative(Native Method) 09-30 15:28:17.358: E/AndroidRuntime(28713): at java.lang.reflect.Method.invoke(Method.java:507) 09-30 15:28:17.358: E/AndroidRuntime(28713): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 09-30 15:28:17.358: E/AndroidRuntime(28713): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 09-30 15:28:17.358: E/AndroidRuntime(28713): at dalvik.system.NativeStart.main(Native Method) 09-30 15:33:17.468: I/Process(28713): Sending signal. PID: 28713 SIG: 9

Answer 1

您根本不应该将值直接包含在您的 SQL 中。相反，请使用参数化 SQL，例如:

Cursor cursor = db.rawQuery("SELECT * FROM category WHERE name=?",
                            new String[] { a });

那样:

• 您无需担心非 ASCII 的表示方式
• 您无需担心转义数据以避免 SQL injection attacks
• 你的 SQL 更容易阅读，没有所有的字符串连接

(在普通的 JDBC 中，您可以为 String 以外的其他数据类型设置参数，这也避免了转换问题 - 看起来这在这里不太可用，但这是参数化 SQL 的常见好处。)