You should do your INSERTs into the base table only

That way you can INSERT queries like these

insert into base_table (a, b, c, x) VALUES (null, 'xxx', 'xxx',1);
insert into base_table (b, c, x) VALUES ('xxx', 'xxx',2);

If you do INSERT queries like these

insert into base_table (a, b, c) VALUES (null, 'xxx', 'xxx');
insert into base_table (b, c) VALUES ('xxx', 'xxx');

then you should assign a default value of 1 for x in the table definition

create table base_table (
  a int unsigned auto_increment primary key,
  b char(10) default null,
  c char(10) default null,
  x tinyint unsigned default 1
);

Otherwise, you should only INSERT into base_table since there exists no mechanism for dynamically switching the default value of x within the definition of a view. The x column has no ability to be selected in the view (because you left it out of the SELECT clause). Consequently, it would definitely have no ability to be updated or assigned in the view.

Give it a Try !!!

Proper crosstab query

First of all, the presented query would not work while you still have char(n) in your table definition - like we discussed under your previous question. You would need to convert to text or varchar first.

This works with your current table definition:

SELECT * FROM crosstab(
   'SELECT postcode_nospace_::text, ageband::text, count(ageband) AS ct
    FROM   adult_social_care.activities_in_localities_asc
    GROUP  BY 1, 2
    ORDER  BY 1'

   ,$$VALUES ('18-24'::text), ('25-34'), ('35-44'), ('45-54'), ('55-64')
           , ('65-74'), ('75-84'), ('85-94'), ('95 AND OVER')$$
   )
AS t("postcode" text
   , "18-24" bigint, "25-34" bigint,"35-44" bigint, "45-54" bigint, "55-64" bigint
   , "65-74" bigint, "75-84" bigint, "85-94" bigint, "95 AND OVER" bigint);

I am also using bigint instead of numeric to save another unnecessary type conversion (count() returns bigint).

Detailed explanation:

• PostgreSQL Crosstab Query

Better table definition

But better ALTER the data type in your table to text like @dezso suggested. Or, if you want to keep the length limit, add a CHECK constraint or use varchar(n). Never use char(n).

ALTER TABLE activities_in_localities_asc
   ALTER COLUMN ageband TYPE varchar(12)
 , ALTER COLUMN postcode_nospace_ TYPE varchar(8);

 ALTER TABLE gazetteers_and_addresses.unit_postcode
   ALTER COLUMN pc_area TYPE varchar(10);

Then you don't need to cast original column values any more:

SELECT * FROM crosstab(
   'SELECT postcode_nospace_, ageband, count(ageband)
    ...

Ideally, though, ageband should be an enum or (my preference) an ID referencing a lookup table, not plain, error-prone text ... key word: normalization.

Add total count

Building on your table, but with text or varchar() columns.

Wrap your original query into a CTE and call the the result twice in a UNION query - the 2nd call adds totals per postcode:

SELECT * FROM crosstab(
  $$WITH cte AS (
      SELECT postcode_nospace_, ageband, count(ageband) AS ct
      FROM   adult_social_care.activities_in_localities_asc  
      GROUP  BY 1, 2
      )
   TABLE  cte  -- original results
   UNION ALL   -- add total per postcode
   SELECT postcode_nospace_, 'total' AS ageband, sum(ct) AS ct
   FROM   cte
   GROUP  BY 1
   ORDER  BY 1$$  -- dollar-quotes to include single quotes easily

   ,$$VALUES ('18-24'::text), ('25-34'), ('35-44'), ('45-54'), ('55-64')
           , ('65-74'), ('75-84'), ('85-94'), ('95 AND OVER'), ('total')$$
   )
AS t("postcode" text
   , "18-24" bigint, "25-34" bigint,"35-44" bigint, "45-54" bigint, "55-64" bigint
   , "65-74" bigint, "75-84" bigint, "85-94" bigint, "95 AND OVER" bigint, "total" bigint);

About the TABLE command:

• Is there a shortcut for SELECT * FROM in psql?

Related CTE examples:

• Combine results of two queries, where the second relies on the first
• Get n grouped categories and sum others into one