================================================================================
add column
================================================================================
alter table foo add bar text;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (table_column_item
          (identifier)
          (identifier))))))

================================================================================
if exists
================================================================================
alter table if exists foo add bar text;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (if_exists)
    (identifier)
    (alter_table_change
      (alter_table_action
        (table_column_item
          (identifier)
          (identifier))))))

================================================================================
add column if not exists
================================================================================
alter table foo add column if not exists bar text;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (if_not_exists)
        (table_column_item
          (identifier)
          (identifier))))))

================================================================================
drop column
================================================================================
alter table foo drop column bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)))))

================================================================================
drop column cascade
================================================================================
alter table foo drop column bar cascade;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
drop column restrict
================================================================================
alter table foo drop column bar restrict;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
drop column if exists
================================================================================
alter table foo drop column if exists bar restrict;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (if_exists)
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
set column default
================================================================================
alter table foo alter bar set default 4;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action
          (number))))))

================================================================================
drop column default
================================================================================
alter table foo alter bar drop default;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action)))))

================================================================================
alter column type
================================================================================
alter table foo alter bar type text;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action
          (alter_column_type
            (identifier)))))))

================================================================================
alter column type(1)
================================================================================
alter table foo alter bar set data type text;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action
          (alter_column_type
            (identifier)))))))

================================================================================
alter column type(2)
================================================================================
alter table foo alter column bar set data type timestamptz using created at time zone 'utc';
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action
          (alter_column_type
            (identifier)
            (time_expression
              (identifier)
              (string))))))))

================================================================================
column set not null
================================================================================
alter table foo alter bar set not null;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action)))))

================================================================================
column drop not null
================================================================================
alter table foo alter bar drop not null;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_column_action)))))

================================================================================
column add constraint
================================================================================
alter table foo add constraint u_bar unique(bar);
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (table_constraint
          (identifier)
          (table_constraint_ty
            (identifier)))))))

================================================================================
column drop constraint
================================================================================
alter table foo drop constraint u_bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)))))

================================================================================
column drop constraint cascade
================================================================================
alter table foo drop constraint u_bar cascade;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
column drop constraint restrict
================================================================================
alter table foo drop constraint u_bar restrict;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
column drop constraint if exists
================================================================================
alter table foo drop constraint if exists u_bar restrict;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (if_exists)
        (identifier)
        (alter_table_fk_ref_action)))))

================================================================================
many changes in columns
================================================================================
alter table foo drop constraint foo, add unique(foo);
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_action
        (identifier))
      (alter_table_action
        (table_constraint
          (table_constraint_ty
            (identifier)))))))

================================================================================
rename column
================================================================================
alter table foo rename column foo to bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_rename_column
        (identifier)
        (identifier)))))

================================================================================
rename constraint
================================================================================
alter table foo rename constraint foo to foo.bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_rename_constraint
        (identifier)
        (identifier)))))

================================================================================
rename table
================================================================================
alter table foo rename to foo.bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_rename_table
        (identifier)))))

================================================================================
change schema
================================================================================
alter table foo set schema bar;
--------------------------------------------------------------------------------

(source_file
  (alter_table_statement
    (identifier)
    (alter_table_change
      (alter_table_change_schema
        (identifier)))))