Question

最近，由于这样的代码，我遇到了一些错误：

Cursor myCursor = myDb.rawQuery(
        "SELECT ... " +
        "  FROM ...complicated join... " +
        " WHERE field1 = ? AND (field2 = ? OR field3 = ?) ",
        new String[] {myField1, myField2});   // Oops, forgot about field3

当发生这种情况时，查询只是默默地忽略丢失的参数，导致错误被忽视。当占位符数量和字段数不匹配时，是否有一些pedantic设置或其他任何可用于使SQLite尖叫（在运行时）的设置？

我知道我可以构建自己的包装器，但我想知道是否有内置的东西......

Answer 1

Android基本上只是将未经检查的args传递给原生sqlite，请参阅http://www.sqlite.org/c3ref/bind_blob.html

如果没有绑定某些内容，则只会将其绑定为NULL。绑定太多应该导致错误

我不知道/没有在Android的源代码中看到任何调试选项进行那种检查，但你可能会编写一些检查你的sql语法的代码：

SQLiteChecker mDbChecked = new SQLiteChecker(mDb);
Cursor c = mDbChecked.rawQuery("select complicated from table where stuff=?",
        new String[] {"one", "two"});

其中SQLiteChecker将是

的内容

/**
 * Simple Delegate for SQLiteDatabase
 */
public class SQLiteChecker {
    private final SQLiteDatabase mDbDelegate;
    public SQLiteChecker(SQLiteDatabase db) {
        mDbDelegate = db;
    }
    // ------------ Delegate methods --------------------//
    public int delete(String table, String whereClause, String[] whereArgs) {
        checkSQL(whereClause, whereArgs);
        return mDbDelegate.delete(table, whereClause, whereArgs);
    }

    public int update(String table, ContentValues values, String whereClause, String[] whereArgs) {
        checkSQL(whereClause, whereArgs);
        return mDbDelegate.update(table, values, whereClause, whereArgs);
    }

    public void execSQL(String sql, Object[] bindArgs) throws SQLException {
        checkSQL(sql, bindArgs);
        mDbDelegate.execSQL(sql, bindArgs);
    }

    public Cursor rawQuery(String sql, String[] selectionArgs) {
        checkSQL(sql, selectionArgs);
        return mDbDelegate.rawQuery(sql, selectionArgs);
    }

    // add more if you need

    // -------------- checking logic -------------------//
    private static void checkSQL(String query, Object[] args) {
        // bit unreliable but simple:
        // just check if amount of ? matches args.length
        int expected = countChar(query, '?');
        int actual = args != null ? args.length : 0;
        if (expected != actual) {
            Log.e("CHECK", "You seem to have messed up [" + query + "]");
            Log.e("CHECK", "expected:" + expected + " actual:" + actual);
        }
    }

    private static int countChar(String string, char ch) {
        if (string == null) return 0;
        int count = 0;
        for (int i = 0; i < string.length(); i++) {
            if (string.charAt(i) == ch)
                count++;
        }
        return count;
    }
}

我可以让SQLiteDatabase抱怨缺少参数吗？

1 个答案: