Fixes gh-1410 Column naming in SQL

Author: pgulutzan

doc/reference/reference_sql/sql_beginners_guide.rst

@@ -607,11 +607,11 @@ The result will look like this:
 
 .. code-block:: none
 
-     +--------------+-----------+-----------+-----------+-------------+
-     | AVG(size)    | SUM(size) | MIN(size) | MAX(size) | COUNT(size) |
-     +--------------+-----------+-----------+-----------+-------------|
-     | 5.413333E+02 | 1624      |         4 |      1432 |           3 |
-     +--------------+-----------+-----------+-----------+-------------+
+     +--------------+-----------+-----------+-----------+-----------+
+     | COLUMN_1     | COLUMN_2  | COLUMN_3  | COLUMN_4  | COLUMN_5  |
+     +--------------+-----------+-----------+-----------+-----------|
+     | 5.413333E+02 | 1624      |         4 |      1432 |         3 |
+     +--------------+-----------+-----------+-----------+-----------+
 
 Suppose that we want aggregations, but aggregations of rows that have some common characteristic.
 Supposing further, we want to divide the rows into two groups, the ones whose names
@@ -628,12 +628,12 @@ The result will look like this:
 
 .. code-block:: none
 
-     +--------------------+--------------+-----------+-----------+-----------+-------------+
-     | SUBSTR(name, 1, 1) | AVG(size)    | SUM(size) | MIN(size) | MAX(size) | CoUNT(size) |
-     +--------------------+--------------+-----------+-----------+-----------|-------------|
-     | b                  |         1432 |      1432 |      1432 |      1432 |           1 |
-     | c                  |           96 |       192 |         4 |       188 |           2 |
-     +--------------------+--------------+-----------+-----------+-----------|-------------+
+     +------------+--------------+-----------+-----------+-----------+-------------+
+     | COLUMN_1   | COLUMN_2     | COLUMN_3  | COLUMN_4  | COLUMN_5  | COLUMN_6    |
+     +------------+--------------+-----------+-----------+-----------|-------------|
+     | b          |         1432 |      1432 |      1432 |      1432 |           1 |
+     | c          |           96 |       192 |         4 |       188 |           2 |
+     +------------+--------------+-----------+-----------+-----------|-------------+
 
 
 **Select with common table expression**

doc/reference/reference_sql/sql_statements_and_clauses.rst

@@ -1813,10 +1813,16 @@ The column name is useful for two reasons:
   then
   the column names in the new table will be the column names in the *select list*.
 
-If ``[[AS] column-name]`` is missing, Tarantool makes a name equal to the
-expression, for example ``SELECT 5 * 88`` will cause the column name to be
-``5 * 88``, but such names may be ambiguous or illegal in other contexts,
-so it is better to say, for example, ``SELECT 5 * 88 AS column1``.
+If ``[[AS] column-name]`` is missing, and the expression is not simply
+the name of a column in the table, then Tarantool makes a name
+:samp:`COLUMN_{n}` where :samp:`{n}` is the number of the non-simple
+expression within the select list, for example
+``SELECT 5.88, table1.x, 'b' COLLATE "unicode_ci" FROM table1;``
+will cause the column names to be COLUMN_1, X, COLUMN_2.
+This is a behavior change in Tarantool 2.6, in earlier versions
+the name would be equal to the expression, 
+see `Issue#3962 <https://github.com/tarantool/tarantool/issues/3962>`_.
+It is still legal to define tables with column names like ``COLUMN_1`` but not recommended.
 
 Examples:
 
@@ -1833,10 +1839,6 @@ Examples:
    -- as a list:
    SELECT 1 AS a, 2 AS b, table1.* FROM table1;
 
-Limitations: (`Issue#3962 <https://github.com/tarantool/tarantool/issues/3962>`_) |br|
-* Names for expressions will change in a future version.
-
-
 .. _sql_from:
 
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

doc/reference/reference_sql/sql_user_guide.rst

@@ -51,7 +51,7 @@ The bottom of the screen should now look like this:
     tarantool> box.execute([[VALUES ('hello');]])
     ---
     - metadata:
-      - name: column1
+      - name: COLUMN_1
         type: string
       rows:
       - ['hello']