Merge pull request #219 from gramian/main

Minor SQL update

src/main/asciidoc/appendix/sql-syntax.adoc

@@ -362,20 +362,19 @@ The conversion of a number to BigDecimal can be done explicitly, using the `bigD
 [[SQL-Collections]]
 **Collections**
 
-ArcadeDB supports two types of collections:
+ArcadeDB supports one type of collection:
 
 - **Lists**: ordered, allow duplicates
-- **Sets**: not ordered (?), no duplicates
  
 The SQL notation allows to create `Lists` with square bracket notation, eg.
 ```
 [1, 3, 2, 2, 4]
 ```
 
-A `List` can be converted to a `Set` using the `.asSet()` method:
+For OrientDB compatibility, the `.asSet()` method is available to remove duplicates from a `List`:
 
 ```
-[1, 3, 2, 2, 4].asSet() = [1, 3, 2, 4] /*  the order of the elements in the resulting set is not guaranteed */
+[1, 3, 2, 2, 4].asSet() = [1, 3, 2, 4] -- The order of the elements in the resulting set is not guaranteed
 ```
 
 [[SQL-Binary]]

src/main/asciidoc/sql/SQL-Drop-Index.adoc

@@ -25,7 +25,7 @@ DROP INDEX <index-name> [ IF EXISTS ]
 
 [source,sql]
 ----
-ArcadeDB> DROP INDEX `Users.Id`
+ArcadeDB> DROP INDEX `Users[Id]`
 ----
 
 For more information, see:

src/main/asciidoc/sql/SQL-Script.adoc

@@ -14,6 +14,9 @@ SQL Batch supports all the ArcadeDB <<SQL-Commands,SQL Commands>>, plus the foll
 ** `&lt;retry&gt;` is the number of retries in case of concurrent modification exception
 * `ROLLBACK` 
 * `LET &lt;variable&gt; = &lt;SQL&gt;`, to assign the result of a SQL command to a variable. To reuse the variable prefix it with the dollar sign `$`.
+
+NOTE: A `LET` can be used as an ephemeral https://en.wikipedia.org/wiki/View_(SQL)[view].
+
 * `IF(&lt;condition&gt;){ &lt;statememt&gt;; [&lt;statement&gt;;]* }`. Look at <<Conditional-Execution,conditional execution>>.
 * `WHILE(&lt;condition&gt;){ &lt;statememt&gt;; [&lt;statement&gt;;]* }`. Look at <<Loops,loop>>.
 * `FOREACH(&lt;variable&gt; IN &lt;expression&gt;){ &lt;statememt&gt;; [&lt;statement&gt;;]* }`. Look at <<Loops,loops>>.

src/main/asciidoc/sql/SQL-Update.adoc

@@ -62,6 +62,12 @@ Remove an element from a list or set of strings:
 ArcadeDB> UPDATE Account REMOVE addresses = 'Foo'
 ----
 
+Append an element to a list or set of strings:
+
+----
+ArcadeDB> UPDATE Account SET addresses += 'Foo'
+----
+
 * Update to remove a value, filtering on value attributes.
 
 Remove addresses based in the city of Rome: