topic Re: ADD COLUMN IF NOT EXISTS does not recognize "IF NOT EXIST". How do I add a column to an existing delta table with SQL if the column does not already exist? in Data Engineering

ADD COLUMN IF NOT EXISTS does not recognize "IF NOT EXIST". How do I add a column to an existing delta table with SQL if the column does not already exist?

Christine — Mon, 05 Dec 2022 13:55:55 GMT

How do I add a column to an existing delta table with SQL if the column does not already exist?

I am using the following code:

<%sql

ALTER TABLE table_name ADD COLUMN IF NOT EXISTS column_name type; >

but it prints the error:

<[PARSE_SYNTAX_ERROR] Syntax error at or near 'EXISTS'(line 1, pos 41)

== SQL ==

ALTER TABLE table_name ADD COLUMN IF NOT EXISTS column_name type

-----------------------------------------^^^>

Re: ADD COLUMN IF NOT EXISTS does not recognize "IF NOT EXIST". How do I add a column to an existing delta table with SQL if the column does not already exist?

UmaMahesh1 — Mon, 05 Dec 2022 17:57:26 GMT

Hi @Christine Pedersen

I guess IF NOT EXISTS or IF EXISTS can be used in conjunction with DROP or PARTITIONS according to the documentation.

If you want to do this the same checking way, you can do using a try catch block in pyspark or as per your language requirement.

import pyspark.sql.utils
try:
  spark.sql("""ALTER TABLE table-name ADD COLUMNS  col-name data-type""")
except pyspark.sql.utils.AnalysisException:
  print("Column already exists")

Hope this helps...

Cheers.