MongoDB中文手册

Mongodb中的mongoexport工具可以把一个collection导出成JSON格式或CSV格式的文件。可以通过参数指定导出的数据项,也可以根据指定的条件导出数据。mongoexport具体用法如下所示:

[[email protected] mongodb]# ./bin/mongoexport --help
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)
  -u [ --username ] arg     username
  -p [ --password ] arg     password
  --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          if dbpath specified, each db is in a separate 
                            directory
  --journal                 enable journaling
  -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

参数说明:

  • -h:指明数据库宿主机的IP
  • -u:指明数据库的用户名
  • -p:指明数据库的密码
  • -d:指明数据库的名字
  • -c:指明collection的名字
  • -f:指明要导出那些列
  • -o:指明到要导出的文件名
  • -q:指明导出数据的过滤条件

实例

test库中存在着一个students集合,集合中数据如下:

> db.students.find()
{ "_id" : ObjectId("5031143350f2481577ea81e5"), "classid" : 1, "age" : 20, "name" : "kobe" }
{ "_id" : ObjectId("5031144a50f2481577ea81e6"), "classid" : 1, "age" : 23, "name" : "nash" }
{ "_id" : ObjectId("5031145a50f2481577ea81e7"), "classid" : 2, "age" : 18, "name" : "james" }
{ "_id" : ObjectId("5031146a50f2481577ea81e8"), "classid" : 2, "age" : 19, "name" : "wade" }
{ "_id" : ObjectId("5031147450f2481577ea81e9"), "classid" : 2, "age" : 19, "name" : "bosh" }
{ "_id" : ObjectId("5031148650f2481577ea81ea"), "classid" : 2, "age" : 25, "name" : "allen" }
{ "_id" : ObjectId("5031149b50f2481577ea81eb"), "classid" : 1, "age" : 19, "name" : "howard" }
{ "_id" : ObjectId("503114a750f2481577ea81ec"), "classid" : 1, "age" : 22, "name" : "paul" }
{ "_id" : ObjectId("503114cd50f2481577ea81ed"), "classid" : 2, "age" : 24, "name" : "shane" }

由上可以看出文档中存在着3个字段:classid、age、name

1.直接导出数据到文件中

[[email protected] mongodb]# ./bin/mongoexport -d test -c students -o students.dat
connected to: 127.0.0.1
exported 9 records

命令执行完后使用ll命令查看,发现目录下生成了一个students.dat的文件

-rw-r--r-- 1 root root   869 Aug 21 00:05 students.dat

查看该文件信息,具体信息如下:

[[email protected] mongodb]# cat students.dat 
{ "_id" : { "$oid" : "5031143350f2481577ea81e5" }, "classid" : 1, "age" : 20, "name" : "kobe" }
{ "_id" : { "$oid" : "5031144a50f2481577ea81e6" }, "classid" : 1, "age" : 23, "name" : "nash" }
{ "_id" : { "$oid" : "5031145a50f2481577ea81e7" }, "classid" : 2, "age" : 18, "name" : "james" }
{ "_id" : { "$oid" : "5031146a50f2481577ea81e8" }, "classid" : 2, "age" : 19, "name" : "wade" }
{ "_id" : { "$oid" : "5031147450f2481577ea81e9" }, "classid" : 2, "age" : 19, "name" : "bosh" }
{ "_id" : { "$oid" : "5031148650f2481577ea81ea" }, "classid" : 2, "age" : 25, "name" : "allen" }
{ "_id" : { "$oid" : "5031149b50f2481577ea81eb" }, "classid" : 1, "age" : 19, "name" : "howard" }
{ "_id" : { "$oid" : "503114a750f2481577ea81ec" }, "classid" : 1, "age" : 22, "name" : "paul" }
{ "_id" : { "$oid" : "503114cd50f2481577ea81ed" }, "classid" : 2, "age" : 24, "name" : "shane" }

参数说明:

  • -d:指明使用的库,本例中为test
  • -c:指明要导出的集合,本例中为students
  • -o:指明要导出的文件名,本例中为students.dat

从上面的结果可以看出,我们在导出数据时没有显示指定导出样式 ,默认导出了JSON格式的数据。如果我们需要导出CSV格式的数据,则需要使用--csv参数,具体如下所示:

[[email protected] mongodb]# ./bin/mongoexport -d test -c students --csv -f classid,name,age -o students_csv.dat
connected to: 127.0.0.1
exported 9 records
[[email protected] mongodb]# cat students_csv.dat 
classid,name,age
1.0,"kobe",20.0
1.0,"nash",23.0
2.0,"james",18.0
2.0,"wade",19.0
2.0,"bosh",19.0
2.0,"allen",25.0
1.0,"howard",19.0
1.0,"paul",22.0
2.0,"shane",24.0
[[email protected] mongodb]# 

参数说明:

  • -csv:指明要导出为csv格式
  • -f:指明需要导出classid、name、age这3列的数据
  • 由上面结果可以看出,mongoexport成功地将数据根据csv格式导出到了students_csv.dat文件中。

MongoDB中文手册