[SPARK-54880] [SQL] SELECT INTO statement support

[srielau]

What changes were proposed in this pull request?

SELECT INTO Spec

Support the single row SELECT INTO statement in SQL Scripting.
SELECT INTO retrieves a single rows and inserts it into a list of local or session variables.
If more than one row is found an error is raised. If no row is found NO DATA is raised (which by default is a NOOP), and no variables are updated.

Example:

BEGIN
  DECLARE shortest STRING;
  SELECT first || ‘ ‘ || last 
    INTO shortest
    FROM VALUES('Bilbo', 'Baggins'), ('Peregrin', 'Tuck')
             AS hobbits(first, last)
    ORDER BY LENGTH(first || ‘ ‘ || last) LIMIT 1;
  VALUES (shortest);
END;

Why are the changes needed?

SELECT INTO is a common SQL Standard command. Supporting it completes teh SQL Scripting stpry and facilitates migration to Spark.

Does this PR introduce any user-facing change?

SELECT INTO Spec

How was this patch tested?

A new test suite was writen.

Was this patch authored or co-authored using generative AI tooling?

Claude

[github-actions]

JIRA Issue Information

=== New Feature SPARK-54880 ===
Summary: SELECT INTO statement
Assignee: None
Status: Open
Affected: ["4.2.0"]

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