Section 1.1: Previous Methods for Renaming Columns

In the past, users had limited options for renaming columns in BigQuery:

1. Use an Alias: By selecting all columns in a table and applying an alias to the column you wish to rename. This often involved creating a view to facilitate the change.
2. Create a New Table: Load the data into a new table that has a schema reflecting the desired column names. Alternatively, you could overwrite the existing table with the new data.

Section 1.2: The New Renaming Feature

Despite the excitement around this new feature, it is still in preview mode, which means many users may need to continue using the previous methods for the time being. However, if you're faced with this task soon, it's worth noting that Google has introduced a helpful solution.

Here’s the syntax and structure for using the ALTER TABLE RENAME COLUMN feature:

ALTER TABLE [IF EXISTS] table_name RENAME COLUMN [IF EXISTS] column_to_column[, ...]

column_to_column := column_name TO new_column_name

Arguments: - IF EXISTS: Ensures that if the specified table or column doesn’t exist, the command has no effect. - table_name: The name of the table you wish to modify. - column_name: The current name of the column you want to change. - new_column_name: The new name for the column, which must not match any existing column names.

This feature is practical and much-needed, promising significant time savings for users. While it remains in preview, there is hope for its eventual general availability without any retraction, as seen in the past.