From d24ee428f38fc519b71f657a5ac2312f2b47abc0 Mon Sep 17 00:00:00 2001
From: Sean Corfield <sean@corfield.org>
Date: Tue, 23 Jul 2024 22:22:25 -0700
Subject: [PATCH] fixes #536

Signed-off-by: Sean Corfield <sean@corfield.org>
---
 CHANGELOG.md      |  1 +
 doc/postgresql.md | 28 +++++++++++++++++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 70da4d5..817793d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changes
 
 * 2.6.next in progress
+  * Address [#536](https://github.com/seancorfield/honeysql/issues/536) by noting what will not work with PostgreSQL (but works with other databases).
   * Address [#533](https://github.com/seancorfield/honeysql/issues/533) by adding `honey.sql/*escape-?*` which can be bound to `false` to prevent `?` being escaped to `??` when used as an operator or function.
   * Address [#526](https://github.com/seancorfield/honeysql/issues/526) by using `format-var` in DDL, instead of `format-entity`.
   * Update JDK test matrix (adopt -> temurin, 19 -> 21).
diff --git a/doc/postgresql.md b/doc/postgresql.md
index 73b5e8d..768d8a8 100644
--- a/doc/postgresql.md
+++ b/doc/postgresql.md
@@ -456,11 +456,6 @@ user=> (-> (alter-table :fruit)
            (drop-column :skin)
            sql/format)
 ["ALTER TABLE fruit DROP COLUMN skin"]
-;; alter table alter column:
-user=> (-> (alter-table :fruit)
-           (alter-column :name [:varchar 64] [:not nil])
-           sql/format)
-["ALTER TABLE fruit ALTER COLUMN name VARCHAR(64) NOT NULL"]
 ;; alter table rename column:
 user=> (-> (alter-table :fruit)
            (rename-column :cost :price)
@@ -473,6 +468,29 @@ user=> (-> (alter-table :fruit)
 ["ALTER TABLE fruit RENAME TO vegetable"]
 ```
 
+The following does not work for PostgreSQL, but does work for several other databases:
+
+```clojure
+;; alter table alter column:
+user=> (-> (alter-table :fruit)
+           (alter-column :name [:varchar 64] [:not nil])
+           sql/format)
+["ALTER TABLE fruit ALTER COLUMN name VARCHAR(64) NOT NULL"]
+```
+
+For PostgreSQL, you need separate statements:
+
+```clojure
+user=> (-> (alter-table :fruit)
+           (alter-column :name :type [:varchar 64])
+           sql/format)
+["ALTER TABLE fruit ALTER COLUMN name TYPE VARCHAR(64)"]
+user=> (-> (alter-table :fruit)
+           (alter-column :name :set [:not nil])
+           sql/format)
+["ALTER TABLE fruit ALTER COLUMN name SET NOT NULL"]
+```
+
 The following PostgreSQL-specific DDL statements are supported
 (with the same syntax as the nilenso library but `sql/format`
 takes slightly different options):