flink運算元（四）

table 的建立方式

# dataset 和datastream 隱式轉化（case

class）
# sink table
# source table
# externalcatalog table
# table api 用法
val orders = tableenv.scan(
"orders"
)val revenue = orders .filter(
'ccountry === "france") .groupby('cid,
'cname'
).select(
'cid, 'cname,
'revenue.sum as 'revsum)
# sql 用法
tableenv.sqlquery(
"select name,sum(age) from t_table group by name"
)

轉化dataset

datastream

tableapi

sql query

dataset--

totable隱式轉化，fromdataset

registerdataset登錄檔

datastream--

totable隱式轉化，fromdatastream

registerdatastream登錄檔

tableapi

todataset[row]

-registertable

sql query

todataset(string, int)

toretractstream

scan

-

# dataset和datastream 註冊成 sqlquery table

//register the datastream as table "mytable"
with fields "f0"
,"f1" 
tableenv.registerdatastream(
"mytable"
, stream)
// register the datastream as table "mytable2"
with fields "mylong"
,"mystring" 
tableenv.registerdatastream(
"mytable2"
, stream,
'mylong, 'mystring)
# dataset和datastream 轉化成table
// convert the datastream into a table with default fields '_1, '_2 
val table1: table = tableenv.fromdatastream(stream)
// convert the datastream into a table with fields 'mylong, 'mystring
val table2: table = tableenv.fromdatastream(stream,
'mylong, 'mystring)
# table轉轉成dataset和datastream 
// convert the table into a dataset of row 
val dsrow: dataset[row]
= tableenv.todataset[row]
(table)
// convert the table into a dataset of tuple2[string, int]
val dstuple: dataset[
(string, int)
]= tableenv.todataset[
(string, int)
](table)
val dsrow: datastream[row]
(table)
val dstuple: datastream[
(string, int)
(string, int)
](table)
# 登錄檔轉和table api 轉化
// sql to table api 
tableenv.registertable(
"table1",.
..) val tapiresult = tableenv.scan(
"table1"
).select(..
.)//from table api to sql 
val projtable: table = tableenv.scan(
"x")
.select(..
.) tableenv.registertable(
"projectedtable"
, projtable)

import org.apache.flink.streaming.api.scala._

import org.apache.flink.table.api.tableenvironment
import org.apache.flink.table.api.scala._
object tableapitest 
case
class order(user:
long
,product:
string
,amount:
int)
}

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