本文為您介紹如何使用IntervalJoin語句。
背景資訊
IntervalJoin語句可以讓兩個流進行JOIN時，左流和右流中每條記錄只關聯另外一條流上滿足定義的時間範圍內的資料，且進行完JOIN後，仍然保留輸入資料流上的時間列，讓您繼續進行基於Event Time的操作。
文法格式
SELECT column-names
FROM table1 [AS <alias1>]
[INNER | LEFT | RIGHT |FULL ] JOIN table2
ON table1.column-name1 = table2.key-name1 AND TIMEBOUND_EXPRESSION支援INNER JOIN、LEFT JOIN、RIGHT JOIN和FULL JOIN，如果直接使用JOIN，預設為INNER JOIN。
暫不支援SEMI JOIN和ANTI JOIN。
TIMEBOUND_EXPRESSION為左右兩個流時間屬性列上的區間條件運算式，支援以下三種條件運算式：
ltime = rtime
ltime >= rtime AND ltime < rtime + INTERVAL '10' MINUTE
ltime BETWEEN rtime - INTERVAL '10' SECOND AND rtime + INTERVAL '5' SECOND
使用樣本
統計下單後4個小時內的物流資訊。
測試資料
訂單表（Orders）
id
productName
orderTime
1
iphone
2024-04-01 10:00:00.0
2
mac
2024-04-01 10:02:00.0
3
huawei
2024-04-01 10:03:00.0
4
pad
2024-04-01 10:05:00.0
物流表（Shipments）
shipId
orderId
status
shiptime
0
1
shipped
2024-04-01 11:00:00.0
1
2
delivered
2024-04-01 17:00:00.0
2
3
shipped
2024-04-01 12:00:00.0
3
4
shipped
2024-04-01 11:30:00.0
測試語句
CREATE TEMPORARY TABLE Orders( id BIGINT, productName VARCHAR, ordertime TIMESTAMP(3), WATERMARK wk FOR ordertime as withOffset(ordertime, 2000) --定義基於ordertime欄位的浮水印，並為其加上了2秒的延遲 ) WITH ( 'connector' = 'kafka', 'topic' = '<yourTopic>', 'properties.bootstrap.servers' = '<yourBrokers>', 'scan.startup.mode' = 'earliest-offset', 'format' = 'csv' ); CREATE TEMPORARY TABLE Shipments( shipId BIGINT, orderId BIGINT, status VARCHAR, shiptime TIMESTAMP(3), WATERMARK wk FOR shiptime as withOffset(shiptime, 2000) --定義基於shiptime欄位的浮水印，並為其加上了2秒的延遲 ) WITH ( 'connector' = 'kafka', 'topic' = '<yourTopic>', 'properties.bootstrap.servers' = '<yourBrokers>', 'scan.startup.mode' = 'earliest-offset', 'format' = 'csv' ); --使用MySQL作為結果表。 CREATE TEMPORARY TABLE rds_output( id BIGINT, productName VARCHAR, status VARCHAR ) WITH ( 'connector' = 'mysql', 'hostname' = '<yourHostname>', 'port' = '3306', 'username' = '<yourUsername>', 'password' = '<yourPassword>', 'database-name' = '<yourDatabaseName>', 'table-name' = '<yourTableName>' ); INSERT INTO rds_output SELECT id, productName, status FROM Orders AS o JOIN Shipments AS s on o.id = s.orderId AND o.ordertime BETWEEN s.shiptime - INTERVAL '4' HOUR AND s.shiptime;測試結果
id(bigint)
productName(varchar)
status(varchar)
1
iphone
shipped
3
huawei
shipped
4
pad
shipped