### What changes were proposed in this pull request?
A few improvements to the sql ref SELECT doc:
1. correct the syntax of SELECT query
2. correct the default of null sort order
3. correct the GROUP BY syntax
4. several minor fixes
### Why are the changes needed?
refine document
### Does this PR introduce any user-facing change?
N/A
### How was this patch tested?
N/A
Closes#27866 from cloud-fan/doc.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
### What changes were proposed in this pull request?
- Sets up links between related sections.
- Add "Related sections" for each section.
- Change to the left hand side menu to reflect the current status of the doc.
- Other minor cleanups.
### Why are the changes needed?
Currently Spark lacks documentation on the supported SQL constructs causing
confusion among users who sometimes have to look at the code to understand the
usage. This is aimed at addressing this issue.
### Does this PR introduce any user-facing change?
Yes.
### How was this patch tested?
Tested using jykyll build --serve
Closes#27371 from dilipbiswal/select_finalization.
Authored-by: Dilip Biswal <dkbiswal@gmail.com>
Signed-off-by: Sean Owen <srowen@gmail.com>
## What changes were proposed in this pull request?
This is a initial PR that creates the table of content for SQL reference guide. The left side bar will displays additional menu items corresponding to supported SQL constructs. One this PR is merged, we will fill in the content incrementally. Additionally this PR contains a minor change to make the left sidebar scrollable. Currently it is not possible to scroll in the left hand side window.
## How was this patch tested?
Used jekyll build and serve to verify.
Closes#25459 from dilipbiswal/ref-doc.
Authored-by: Dilip Biswal <dbiswal@us.ibm.com>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
