@Jyoti jโ :
1) Yes, it is possible to pass a CTE (Common Table Expression) SQL statement into Spark JDBC. However, the ability to pass CTEs through Spark JDBC depends on the version of Spark you are using.
In Spark 2.x versions, CTEs are not supported in Spark JDBC. However, in Spark 3.x versions, CTEs are supported. Therefore, if you are using Spark 3.4, you should be able to pass a CTE SQL statement through Spark JDBC. To use CTEs with Spark JDBC in Spark 3.4, you need to make sure that you use the "subquery" option in the JDBC options
Here's an example Python code snippet to use Common Table Expressions (CTEs) with Spark JDBC in Spark 3.4:'
from pyspark.sql import SparkSession
# create a SparkSession
spark = SparkSession.builder \
.appName("CTE with JDBC in Spark 3.4") \
.getOrCreate()
# configure Spark to use the JDBC driver
spark.conf.set("spark.sql.catalog.jdbc.driver", "com.mysql.jdbc.Driver")
# create a temporary view using a CTE
spark.sql("""
WITH my_cte AS (
SELECT col1, col2
FROM my_table
WHERE col3 = 'some_value'
)
SELECT col1, AVG(col2) as avg_col2
FROM my_cte
GROUP BY col1
""").createOrReplaceTempView("my_temp_view")
# use the temporary view to query a remote database via JDBC
jdbc_df = spark.read \
.format("jdbc") \
.option("url", "jdbc:mysql://localhost:3306/my_db") \
.option("dbtable", "my_temp_view") \
.option("user", "my_username") \
.option("password", "my_password") \
.load()
# show the results
jdbc_df.show()
2) Some examples are as below
Top function:
SQL Server: SELECT TOP 1 * FROM my_table
Azure Databricks: SELECT * FROM my_table LIMIT 1
Date functions:
SQL Server: DATEADD(day, 7, my_date) to add 7 days to a date
Azure Databricks: DATE_ADD(my_date, INTERVAL 7 DAYS) to add 7 days to a date
Substring function:
SQL Server: SUBSTRING(my_string, 1, 3) to get the first 3 characters of a string
Azure Databricks: SUBSTR(my_string, 1, 3) to get the first 3 characters of a string
String concatenation:
SQL Server: SELECT 'Hello ' + 'world' to concatenate two strings
Azure Databricks: SELECT CONCAT('Hello ', 'world') to concatenate two strings
Date formatting:
SQL Server: SELECT FORMAT(my_date, 'dd/MM/yyyy') to format a date as dd/MM/yyyy
Azure Databricks: SELECT DATE_FORMAT(my_date, 'dd/MM/yyyy') to format a date as dd/MM/yyyy
