如何删除重复的数据库记录?

i have a list with some items.The use can save some of them in a database,as favorites.My problem is that i m getting duplicated records in the database if he try to add the same item two times in the favorites.How can i fix it?

我有一些项目的清单。这种用法可以将其中一些保存到数据库中作为收藏。我的问题是，如果他试图在收藏夹中两次添加相同的条目，那么我将在数据库中得到重复的记录。我怎样才能修好它呢?

i was thinking something like

我想的是

ourDatabase.rawQuery("DELETE FROM "+DBHelper.DATABASE_TABLE+" WHERE"+DBHelper.NAME+" EQUALS "+DBHelper.NAME+");",null);

but it's not working.

但这不是工作。

This is my create Entry method

这是我的create Entry方法

public void createEntry(String name, String dodes) {

         try {        
            ContentValues cv = new ContentValues();
            cv.put(NAME, name);
            cv.put(DODES, dodes);

              //  ourDatabase.rawQuery("DELETE FROM "+DBHelper.DATABASE_TABLE+" WHERE "+DBHelper.NAME+" = "+DBHelper.NAME+");",null);
                ourDatabase.insert("DB", null, cv); 

        } catch (Exception e) {
            Log.e("Exception in insert :", e.toString());
            e.printStackTrace();
        }
    }

2 个解决方案

#1

Before inserting, check to see if an item with the same name already exists. If so, do an update instead of an insert.

在插入之前，检查具有相同名称的项是否已经存在。如果是的话，做一个更新而不是插入。

Cursor crsr = null;
try
{
  crsr = ourDatabase.rawQuery("SELECT _id FROM "+DBHelper.DATABASE_TABLE
      +" WHERE "+DBHelper.NAME+"='"+name+"'", null);
}
catch ( Exception excp )
{
  crsr = null;
}
if ( (crsr == null) || (crsr.getCount() < 1) )
  // Insert item
else
  // Update item

#2

The simple answer is to ensure that the record is "unique".

简单的答案是确保记录是“唯一的”。

You can do this inside the database by adding a "unique index".

您可以在数据库中添加“惟一索引”来实现这一点。

We want something like

我们希望类似的

CREATE UNIQUE INDEX unique_name ON some_table(name)

So something like this in code;

代码中有这样的东西;

"CREATE UNIQUE INDEX unique_name ON "+
DBHelper.DATABASE_TABLE+
"("+DBHelper.NAME+")"

This means that if you try and insert a duplicate, you will get an error.

这意味着如果您尝试插入一个副本，您将会得到一个错误。

Therefore you'll also need to add code that checks whether the name already exists, before you try and do it.

因此，您还需要添加代码来检查名称是否已经存在，然后再尝试执行它。

#1