fix: Move DB agnostic sections out of sqlite database guide

guides/databases-sqlite.md

@@ -382,88 +382,6 @@ SELECT.from.localized(Books)
 SELECT.one.localized(Books)
 ```
 
-
-
-### Standard Operators {.impl .node}
-
-The new database services guarantee identical behavior of these logic operators:
-
-- `==`, `=` — with `= null` being translated to `is null`
-- `!=`,  `<>`  — with `!=` translated to `IS NOT` in SQLite
-
-* `<`, `>`, `<=`, `>=`, `IN`, `LIKE` — are supported as is in standard SQL
-
-In particular, the translation of `!=` to `IS NOT` in SQLite — or to `IS DISTINCT FROM` in standard SQL, or to an equivalent polyfill in SAP HANA — greatly improves the portability of your code.
-
-> These operators are available for runtime queries, but not in CDS files.
-
-
-### Standard Functions {.impl .node}
-
-A specified set of standard functions is now supported in a **database-agnostic**, hence portable way, and translated to database-specific variants or polyfills. These functions are by and large the same as specified in OData:
-
-* `concat(x,y,...)` — concatenates the given strings
-* `contains(x,y)` — checks whether `y` is contained in `x`, may be fuzzy
-* `search(xs,y)` — checks whether `y` is contained in any of `xs`, may be fuzzy
-* `startswith(x,y)` — checks whether `y` starts with `x`
-* `endswith(x,y)` — checks whether `y` ends with `x`
-* `matchesPattern(x,y)` — checks whether `x` matches regex `y`
-* `substring(x,i,n)` — extracts a substring from `x` starting at `i` with length `n` <sup>1</sup>
-* `indexof(x,y)` — returns the (zero-based) index of the first occurrence of `y` in `x`
-* `length(x)` — returns the length of string `x`
-* `tolower(x)` — returns all-lowercased `x`
-* `toupper(x)` — returns all-uppercased `x`
-* `ceiling(x)` — returns ceiled `x`
-* `session_context(v)` — with standard variable names → [see below](#session-variables)
-* `year` `month`, `day`, `hour`, `minute`, `second` — return parts of a datetime
-
-> <sup>1</sup> Argument `n` is optional.
-> These functions are only supported within runtime queries, but not in CDS files.
-
-The database service implementation translates these to the best-possible native SQL functions, thus enhancing the extent of **portable** queries.
-
-CQL query:
-
-```sql
-SELECT from Books where search((title,descr),'y')
-```
-
-Translated native SQLite query:
-
-```sql
-SELECT * from sap_capire_bookshop_Books
- WHERE ifnull(instr(lower(title),lower('y')),0)
-    OR ifnull(instr(lower(descr),lower('y')),0)
-```
-
-> Note: only single values are supported for the second argument `y`.
-
-::: warning Case-sensitive
-
-You have to write these functions exactly as given; all-uppercase usages aren't supported.
-
-:::
-
-
-
-### SAP HANA Functions {.impl .node}
-
-In addition to the standard functions, which all new database services support, the new SQLite service also supports these common SAP HANA functions, to further increase the scope for portable testing:
-
-- `years_between`
-- `months_between`
-- `days_between`
-- `seconds_between`
-- `nano100_between`
-
-With open source and the new database service architecture, we also have methods in place to enhance this list by custom implementation.
-
-> Both usages are allowed here: all-lowercase as given above, as well as all-uppercase.
-
-
-
-
-
 ### Session Variables {.impl .node}
 
 The new SQLite service can leverage  [*better-sqlite*](https://www.npmjs.com/package/better-sqlite3)'s user-defined functions to support *session context* variables. In particular, the pseudo variables `$user.id`, `$user.locale`,  `$valid.from`, and `$valid.to` are available in native SQL queries as shown below:

guides/databases.md

@@ -327,6 +327,85 @@ Select.from(AUTHOR)
 
 </div>
 
+### Standard Operators {.impl .node}
+
+The new database services guarantee identical behavior of these logic operators:
+
+`<`, `>`, `<=`, `>=`, `<>`, `=`, `IN`, `LIKE` — are supported as is in standard SQL.
+
+With special mappings for the following boolean operators:
+
+| Operator  | `@cap-js/sqlite` | `@cap-js/hana` | `@cap-js/postgres` |
+|-----------|------------------|----------------|---------------------|
+| `= NULL`  | `is NULL`        | `is NULL`      | `is NULL`           |
+| `!=`      | `<>`             | `!=`           | `<>`                |
+| `!= NULL` | `is not NULL`    | `is not NULL`  | `is not NULL`       |
+
+
+In particular, the translation of `!=` to `IS NOT` in SQLite — or to an equivalent polyfill in SAP HANA — greatly improves the portability of your code.
+
+> These operators are available for runtime queries, but not in CDS files.
+
+
+### Standard Functions {.impl .node}
+
+A specified set of standard functions is now supported in a **database-agnostic**, hence portable way, and translated to database-specific variants or polyfills. These functions are by and large the same as specified in OData:
+
+* `concat(x,y,...)` — concatenates the given strings
+* `contains(x,y)` — checks whether `y` is contained in `x`, may be fuzzy
+* `search(xs,y)` — checks whether `y` is contained in any of `xs`, may be fuzzy
+* `startswith(x,y)` — checks whether `y` starts with `x`
+* `endswith(x,y)` — checks whether `y` ends with `x`
+* `matchesPattern(x,y)` — checks whether `x` matches regex `y`
+* `substring(x,i,n)` — extracts a substring from `x` starting at `i` with length `n` <sup>1</sup>
+* `indexof(x,y)` — returns the (zero-based) index of the first occurrence of `y` in `x`
+* `length(x)` — returns the length of string `x`
+* `tolower(x)` — returns all-lowercased `x`
+* `toupper(x)` — returns all-uppercased `x`
+* `ceiling(x)` — returns ceiled `x`
+* `session_context(v)` — with standard variable names → [see below](#session-variables)
+* `year` `month`, `day`, `hour`, `minute`, `second` — return parts of a datetime
+
+> <sup>1</sup> Argument `n` is optional.
+> These functions are only supported within runtime queries, but not in CDS files.
+
+The database service implementation translates these to the best-possible native SQL functions, thus enhancing the extent of **portable** queries.
+
+CQL query:
+
+```sql
+SELECT from Books where search((title,descr),'y')
+```
+
+Translated native SQLite query:
+
+```sql
+SELECT * from sap_capire_bookshop_Books
+ WHERE ifnull(instr(lower(title),lower('y')),0)
+    OR ifnull(instr(lower(descr),lower('y')),0)
+```
+
+> Note: only single values are supported for the second argument `y`.
+
+::: warning Case-sensitive
+
+You have to write these functions exactly as given; all-uppercase usages aren't supported.
+
+:::
+
+### SAP HANA Functions {.impl .node}
+
+In addition to the standard functions, which all `@cap-js` database services support, `@cap-js/sqlite` and `@cap-js/postgres` also support these common SAP HANA functions, to further increase the scope for portable testing:
+
+- `years_between`
+- `months_between`
+- `days_between`
+- `seconds_between`
+- `nano100_between`
+
+With open source and the new database service architecture, we also have methods in place to enhance this list by custom implementation.
+
+> Both usages are allowed here: all-lowercase as given above, as well as all-uppercase.
 
 
 ### Native DB Queries