mongoexport用法：
/*****
Export MongoDB data to CSV, TSV or JSON files.
options:
--help produce help message
-v [ --verbose ] be more verbose (include multiple times
for more verbosity e.g. -vvvvv)
--version print the program's version and exit
-h [ --host ] arg mongo host to connect to ( <set
name>/s1,s2 for sets)
--port arg server port. Can also use --host
hostname:port
--ipv6 enable IPv6 support (disabled by
default)
--ssl use SSL for all connections
-u [ --username ] arg username
-p [ --password ] arg password
--authenticationDatabase arg user source (defaults to dbname)
--authenticationMechanism arg (=MONGODB-CR)
authentication mechanism
--dbpath arg directly access mongod database files
in the given path, instead of
connecting to a mongod server - needs
to lock the data directory, so cannot
be used if a mongod is currently
accessing the same path
--directoryperdb each db is in a separate directly
(relevant only if dbpath specified)
--journal enable journaling (relevant only if
dbpath specified)
-d [ --db ] arg database to use
-c [ --collection ] arg collection to use (some commands)
-f [ --fields ] arg comma separated list of field names
e.g. -f name,age
--fieldFile arg file with fields names - 1 per line
-q [ --query ] arg query filter, as a JSON string
--csv export to csv instead of json
-o [ --out ] arg output file; if not specified, stdout
is used
--jsonArray output to a json array rather than one
object per line
-k [ --slaveOk ] arg (=1) use secondaries for export if
available, default true
--forceTableScan force a table scan (do not use
$snapshot)
/****/
具体例子（导出特定表中数据为csv格式）
mongoexport -h IP --port 端口 -u 用户名 -p 密码 -d 数据库 -c 表名 -f 字段1，字段2 -q‘{条件导出}’ --csv -o 文件名