mongodb操作之使用javaScript实现多表关联查询
一、数据控制
mongodb操作数据量控制,千万控制好,不要因为操作的数据量过多而导致失败。
演示一下发生此类错误的错误提示:
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" 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二、多表关联查询实现
/*
声明变量bridge,用来记录两个集合所连接的桥梁。
相当于sql语句中的Join on语句,on后边跟的条件。
有了桥梁以后,再进行关联那就是易如反掌的事情啦。
关联桥梁所存储的数据是什么样的类型就需要根据你自己的需求来进行创建了。
我这里用一个对象来作为桥梁,然后调用对象中的属性。
*/
var bridge = db.info.findOne();
/* javaScript语言是弱类型的语言,对于返回值是什么样的类型一定要做到心中有数。
在执行db.info.findOne()语句后,这里的返回值可以理解为一个对象,类似于一个javaBean
而在这里存储的所有的字段以及字段值(我用sql语句的说法更易理解)相当于对象的属性。 */ print(bridge.userid)
/*
使用print语句可以打印出上面语句返回的对象信息,进一步验证返回值是否如我们的猜测。
在这里userid这个字段本来是集合中的一个文档名称,即理解为一个表中的字段名称。
这里却相当于一个对象的属性。
*/ //循环用什么都可以,只要能够控制住次数,千万不要因为数据量太大而导致操作失败。
for(info = db.info.findOne({"userid":bridge.userid}),
//以上这句代码就是用来匹配集合中符合条件的,可以是任意mongodb的查询语句
//只要语句满足你的需求就可以,可以灵活变换。
error = db.warning.findOne({"userid":bridge.userid}),
//上边的这条语句同上
i = 0;i<1;i++){//这里就是控制循环次数的啦。
print(info,error);
//打印出我们匹配后的结果。
//关联查询如此简单。
}
我的查询结果:
aaarticlea/png;base64,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" alt="" />
logtype其实就是我的集合名称。
综上:其实就两个点。
1、明确桥梁
2、控制循环,如果数据量小的话就不用控制了,我的数据量太多了。
不管你有多少表,我相信只要掌握住此思路,一定可以轻松的写出多表关联代码,轻松实现多表关联。
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