如何使用 Spark 在 MySQL (JDBC) 上执行连接?
问题描述：
我想通过 Spark 从 MySQL 读取数据.我看到的 API 能够从特定表中读取数据.类似的东西，
I would like to read data from MySQL through Spark. The API which I saw is able to read data from specific table. something like,
val prop = new java.util.Properties
prop.setProperty("user", "<username>")
prop.setProperty("password", "<password>")
sparkSession.read.jdbc("jdbc:mysql://????:3306/???", "some-table", prop)
现在，我想对连接表执行查询.有谁知道怎么做(在数据库方面，而不是使用 Spark SQL)?
Now, I would like to perform a query for join tables. Does anyone know how to do it (on the database side, not with Spark SQL) ?
谢谢，
伊兰
答
您需要使用table"参数作为查询:
You'll need to use the "table " argument as a query:
val table = "(SELECT foo JOIN bar ON foo.id = bar.id) as t"
spark.read.jdbc("jdbc:mysql://????:3306/???", table, prop)
您应该注意，为您的查询指定别名很重要，否则将不起作用.
You should note that giving an alias to your query is important or this won't work.