MongoDB数据类型如下：
| 类型 | 对应数字 | 别名 | 说明 |
| Double1 | 1 | double | |
| String | 2 | string | |
| Object | 3 | object | |
| Array | 4 | array | |
| Binary data | 5 | binData | |
| Undefined | 6 | undefined | 弃用 |
| ObjectId | 7 | objectId | |
| Boolean | 8 | “bool” | |
| Date | 9 | “date” | |
| Null | 10 | “null” | |
| Regular Expression | 11 | “regex” | |
| DBPointer | 12 | “dbPointer” | |
| JavaScript | 13 | “javascript” | |
| Symbol | 14 | “symbol” | |
| JavaScript(with scope) | 15 | “javascriptWithScope” | |
| 32-bit integer | 16 | “int” | |
| Timestamp | 17 | “timestamp” | |
| 64-bit integer | 18 | “long” | |
| Min key | -1 | “minKey” | |
| Max key | 127 | “maxKey” |
js修改语句：
db.getCollection(‘log_pages_day‘).find( {‘uv‘ : { $type : 18 }} ).forEach( function(x) { x.uv =NumberInt(x.uv); db.log_pages_day.save(x); })
原文：http://www.cnblogs.com/loyung/p/7611682.html