MongoDB：无条件更新？
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MongoDB: unconditional updates?
提问by Matt Diamond
This seems like a silly question but I haven't yet found the answer. If I simply wanted to add the same field->value to EVERY record in a MongoDB collection, what would be the appropriate shell command to do so? I tried doing a multi update with a blank query ({}) but that resulted in this error:
这似乎是一个愚蠢的问题，但我还没有找到答案。如果我只是想将相同的 field->value 添加到 MongoDB 集合中的每条记录，那么合适的 shell 命令是什么？我尝试使用空白查询 ({}) 进行多更新，但导致此错误：
multi update only works with $ operators
多重更新仅适用于 $ 运算符
I'm a bit puzzled about how to get around this. Any suggestions?
我对如何解决这个问题感到有些困惑。有什么建议？
回答by Cameron
The error says it all: You can only modify multiple documents using the $modifier operators. You probably had something like this:
错误说明了一切：您只能使用$修饰符操作符修改多个文档。你可能有这样的事情：
> db.coll.update({ }, { a: 'b' }, false, true);
Which would normally replacethe first object in the collection with { a: 'b' }if multiwas false. You wouldn't want to replace all the objects in your collection with the same document!
这通常会用if为 false替换集合中的第一个对象。您不想用同一个文档替换集合中的所有对象！{ a: 'b' }multi
Use the $setoperatorinstead:
改用$set运算符：
> db.coll.update({ }, { '$set': { a: 'b' } }, false, true);
This will set the aproperty of every document (creating it as necessary) to 'b'.
这会将a每个文档的属性（根据需要创建）设置为'b'.
