Split HANA, CDS, SQL into its own sidebar section and add ABAP SQL page

Move CDS and Fuzzy Search from the RAP, EML, HANA section into a new
HANA, CDS, SQL section and add a new ABAP SQL page covering SELECT,
filtering, joins, aggregations, and data changes.

Author: claude

docs/.vitepress/config.mjs

@@ -234,13 +234,21 @@ export default defineConfig({
             ],
           },
           {
-            text: "RAP, EML, HANA",
-            link: "/development/specific/cds",
+            text: "RAP, EML",
+            link: "/development/specific/eml",
             collapsed: true,
             items: [
-              { text: "CDS", link: "/development/specific/cds" },
               { text: "EML", link: "/development/specific/eml" },
               { text: "Draft Handling", link: "/development/specific/draft" },
+            ],
+          },
+          {
+            text: "HANA, CDS, SQL",
+            link: "/development/specific/cds",
+            collapsed: true,
+            items: [
+              { text: "CDS", link: "/development/specific/cds" },
+              { text: "ABAP SQL", link: "/development/specific/abap_sql" },
               { text: "Fuzzy Search", link: "/development/specific/fuzzy_search" },
             ],
           },

docs/development/specific/abap_sql.md

@@ -0,0 +1,113 @@
+---
+outline: [2, 4]
+---
+# ABAP SQL
+
+ABAP SQL is the standard way to read and change data in the database directly from ABAP. In an abap2UI5 controller you can issue `SELECT`, `INSERT`, `UPDATE`, `DELETE`, and `MODIFY` statements the same way as in any ABAP program, and bind the result straight to a UI5 view.
+
+### Read Data
+
+The example below selects flights from the `sflight` table and shows them in a UI5 table:
+```abap
+CLASS z2ui5_cl_sample_sql DEFINITION PUBLIC.
+
+  PUBLIC SECTION.
+    INTERFACES z2ui5_if_app.
+    DATA mt_flights TYPE STANDARD TABLE OF sflight WITH EMPTY KEY.
+
+ENDCLASS.
+
+CLASS z2ui5_cl_sample_sql IMPLEMENTATION.
+  METHOD z2ui5_if_app~main.
+
+    IF client->check_on_init( ).
+
+      SELECT FROM sflight
+        FIELDS carrid, connid, fldate, price, currency
+        ORDER BY carrid, connid, fldate
+        INTO TABLE @mt_flights
+        UP TO 50 ROWS.
+
+      DATA(view)  = z2ui5_cl_xml_view=>factory( )->page( ).
+      DATA(table) = view->table( client->_bind( mt_flights ) ).
+
+      table->columns(
+           )->column( )->text( `Carrier` )->get_parent(
+           )->column( )->text( `Connection` )->get_parent(
+           )->column( )->text( `Date` )->get_parent(
+           )->column( )->text( `Price` ).
+
+      table->items( )->column_list_item( )->cells(
+         )->text( `{CARRID}`
+         )->text( `{CONNID}`
+         )->text( `{FLDATE}`
+         )->text( `{PRICE} {CURRENCY}` ).
+
+      client->view_display( view->stringify( ) ).
+
+    ENDIF.
+
+  ENDMETHOD.
+ENDCLASS.
+```
+
+### Filter with a Search Field
+
+Bind the search term with `_bind_edit( )` and re-run the `SELECT` on every `SEARCH` event:
+```abap
+CASE abap_true.
+
+  WHEN client->check_on_init( ).
+    load_data( ).
+    render( ).
+
+  WHEN client->check_on_event( `SEARCH` ).
+    load_data( ).
+    client->view_model_update( ).
+
+ENDCASE.
+```
+
+```abap
+METHOD load_data.
+
+  SELECT FROM scarr
+    FIELDS carrid, carrname, url
+    WHERE @mv_search = ''
+       OR carrname LIKE @( |%{ mv_search }%| )
+    INTO TABLE @mt_carriers
+    UP TO 100 ROWS.
+
+ENDMETHOD.
+```
+
+### Aggregations and Joins
+
+Aggregations and joins work like in any ABAP report — the result table is then bound to the view:
+```abap
+SELECT FROM sflight AS f
+  INNER JOIN scarr AS c ON c~carrid = f~carrid
+  FIELDS f~carrid, c~carrname, SUM( f~seatsocc ) AS total_seats
+  GROUP BY f~carrid, c~carrname
+  ORDER BY total_seats DESCENDING
+  INTO TABLE @DATA(lt_stats)
+  UP TO 20 ROWS.
+```
+
+### Change Data
+
+`INSERT`, `UPDATE`, `DELETE`, and `MODIFY` are issued from event handlers — wrap them in a transaction and commit explicitly:
+```abap
+WHEN client->check_on_event( `SAVE` ).
+
+  MODIFY zorders FROM TABLE @mt_orders.
+  IF sy-subrc = 0.
+    COMMIT WORK.
+  ELSE.
+    ROLLBACK WORK.
+  ENDIF.
+```
+
+::: tip
+For data sourced from the Virtual Data Model, prefer reading from a [CDS view](./cds.md) instead of base tables — you get business semantics, associations, and authorization checks out of the box.
+:::