doc: Clarify that COLUMN is optional in ALTER TABLE ... ADD/DROP COLUMN.

In ALTER TABLE ... ADD/DROP COLUMN, the COLUMN keyword is optional. However,
part of the documentation could be read as if COLUMN were required, which may
mislead users about the command syntax.

This commit updates the ALTER TABLE documentation to clearly state that
COLUMN is optional for ADD and DROP.

Also this commit adds regression tests covering ALTER TABLE ... ADD/DROP
without the COLUMN keyword.

Backpatch to all supported versions.

Author: Chao Li <lic@highgo.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CAEoWx2n6ShLMOnjOtf63TjjgGbgiTVT5OMsSOFmbjGb6Xue1Bw@mail.gmail.com
Backpatch-through: 14

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index acdd7f684bf2f7e487cfdb5afb60443171f8dec9..caf9c07114298c1f5cfd9687035eefc8b628b6a5 100644 (file)
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -154,7 +154,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
 
   <variablelist>
    <varlistentry>
-    <term><literal>ADD COLUMN [ IF NOT EXISTS ]</literal></term>
+    <term><literal>ADD [ COLUMN ] [ IF NOT EXISTS ]</literal></term>
     <listitem>
      <para>
       This form adds a new column to the table, using the same syntax as
@@ -166,7 +166,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
    </varlistentry>
 
    <varlistentry>
-    <term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
+    <term><literal>DROP [ COLUMN ] [ IF EXISTS ]</literal></term>
     <listitem>
      <para>
       This form drops a column from a table.  Indexes and

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 361619b015ed9ab5d6cb278123a4a7eb0c9da404..11b394c6d7199027054a7f739a98aa7402a12161 100644 (file)
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3735,6 +3735,16 @@ Referenced by:
 ALTER TABLE test_add_column
        ADD COLUMN IF NOT EXISTS c5 SERIAL CHECK (c5 > 10);
 NOTICE:  column "c5" of relation "test_add_column" already exists, skipping
+ALTER TABLE test_add_column
+       ADD c6 integer; -- omit COLUMN
+ALTER TABLE test_add_column
+       ADD IF NOT EXISTS c6 integer;
+NOTICE:  column "c6" of relation "test_add_column" already exists, skipping
+ALTER TABLE test_add_column
+       DROP c6; -- omit COLUMN
+ALTER TABLE test_add_column
+       DROP IF EXISTS c6;
+NOTICE:  column "c6" of relation "test_add_column" does not exist, skipping
 \d test_add_column*
                             Table "public.test_add_column"
  Column |  Type   | Collation | Nullable |                   Default                   

diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index a5ad6bc0bbec8e8b5a0fe7c58bf13ad4a11ee460..9894b159a1a76fb9e521ea08257370638824e66e 100644 (file)
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2305,6 +2305,14 @@ ALTER TABLE test_add_column
 \d test_add_column
 ALTER TABLE test_add_column
        ADD COLUMN IF NOT EXISTS c5 SERIAL CHECK (c5 > 10);
+ALTER TABLE test_add_column
+       ADD c6 integer; -- omit COLUMN
+ALTER TABLE test_add_column
+       ADD IF NOT EXISTS c6 integer;
+ALTER TABLE test_add_column
+       DROP c6; -- omit COLUMN
+ALTER TABLE test_add_column
+       DROP IF EXISTS c6;
 \d test_add_column*
 DROP TABLE test_add_column;
 \d test_add_column*