diff --git a/rootfs_overlay/lkmc/nodejs/sequelize/association.js b/rootfs_overlay/lkmc/nodejs/sequelize/association.js
index b22f85b..21de415 100755
--- a/rootfs_overlay/lkmc/nodejs/sequelize/association.js
+++ b/rootfs_overlay/lkmc/nodejs/sequelize/association.js
@@ -9,6 +9,7 @@ const sequelize = new Sequelize({
   dialect: 'sqlite',
   storage: 'tmp.' + path.basename(__filename) + '.sqlite',
 });
+
 (async () => {
 const Comment = sequelize.define('Comment', {
   body: { type: DataTypes.STRING },
@@ -45,7 +46,10 @@ await Comment.create({body: 'u1c0', UserId: u1.id});
   const u0Comments = await Comment.findAll({
     where: { UserId: u0.id },
     order: [['id', 'ASC']],
-    include: [{ model: User }],
+    include: User,
+    // Equivalent alternatives in this case.
+    //include: [User],
+    //include: [{ model: User }],
   });
   assert(u0Comments[0].body === 'u0c0');
   assert(u0Comments[1].body === 'u0c1');
@@ -58,6 +62,7 @@ await Comment.create({body: 'u1c0', UserId: u1.id});
 
 // Nicer higher level way.
 {
+  console.log(Object.getOwnPropertyNames(u0));
   const u0Comments = await u0.getComments({
     include: [{ model: User }],
   });
@@ -79,14 +84,65 @@ await Comment.create({body: 'u1c0', UserId: u1.id});
 }
 
 // Removal auto-cascades.
-const u0id = u0.id
-await u0.destroy()
-assert((await Comment.findAll({
-  where: { UserId: u0id },
-})).length === 0);
-assert((await Comment.findAll({
-  where: { UserId: u1.id },
-})).length === 1);
+{
+  const u0id = u0.id
+  await u0.destroy()
+  assert((await Comment.findAll({
+    where: { UserId: u0id },
+  })).length === 0);
+  assert((await Comment.findAll({
+    where: { UserId: u1.id },
+  })).length === 1);
+}
+
+// as aliases.
+// Allows us to use a nicer name for a relation rather than the exact class name.
+// E.g. here we name the User of a Comment as a "author".
+// And mandatory do diambiguate multiple associations with a single type.
+{
+  const CommentAs = sequelize.define('CommentAs', {
+    body: { type: DataTypes.STRING },
+  }, {});
+  const UserAs = sequelize.define('UserAs', {
+    name: { type: DataTypes.STRING },
+  }, {});
+  UserAs.hasMany(CommentAs)
+  CommentAs.belongsTo(UserAs, {as: 'author'})
+  await sequelize.sync({force: true});
+  const u0 = await UserAs.create({name: 'u0'})
+  const u1 = await UserAs.create({name: 'u1'})
+  await CommentAs.create({body: 'u0c0', authorId: u0.id});
+  await CommentAs.create({body: 'u0c1', authorId: u0.id});
+  await CommentAs.create({body: 'u1c0', authorId: u1.id});
+
+  {
+    const u0Comments = await CommentAs.findAll({
+      where: { authorId: u0.id },
+      order: [['id', 'ASC']],
+      // Instead of include: UserAs
+      include: 'author',
+    });
+    assert(u0Comments[0].body === 'u0c0');
+    assert(u0Comments[1].body === 'u0c1');
+    assert(u0Comments[0].authorId === u0.id);
+    assert(u0Comments[1].authorId === u0.id);
+    assert(u0Comments[0].author.name === 'u0');
+    assert(u0Comments[1].author.name === 'u0');
+  }
+
+  // Trying with the higher level getter.
+  {
+    // TODO
+    // u0.getComments is not a function
+    //const u0Comments = await u0.getComments({
+    //  include: 'author',
+    //});
+    //assert(u0Comments[0].body === 'u0c0');
+    //assert(u0Comments[1].body === 'u0c1');
+    //assert(u0Comments[0].author.name === 'u0');
+    //assert(u0Comments[1].author.name === 'u0');
+  }
+}
 
 await sequelize.close();
 })();
diff --git a/rootfs_overlay/lkmc/nodejs/sequelize/index.js b/rootfs_overlay/lkmc/nodejs/sequelize/index.js
index 1c31b4e..fb098ff 100755
--- a/rootfs_overlay/lkmc/nodejs/sequelize/index.js
+++ b/rootfs_overlay/lkmc/nodejs/sequelize/index.js
@@ -44,7 +44,8 @@ await sequelize.authenticate();
 const IntegerNames = sequelize.define('IntegerNames', {
   value: {
     type: DataTypes.INTEGER,
-    allowNull: false
+    allowNull: false,
+    unique: true,
   },
   name: {
     type: DataTypes.STRING,
diff --git a/rootfs_overlay/lkmc/nodejs/sequelize/sync_alter.js b/rootfs_overlay/lkmc/nodejs/sequelize/sync_alter.js
new file mode 100755
index 0000000..5ac5e77
--- /dev/null
+++ b/rootfs_overlay/lkmc/nodejs/sequelize/sync_alter.js
@@ -0,0 +1,110 @@
+#!/usr/bin/env node
+
+// https://stackoverflow.com/questions/17708620/sequelize-changing-model-schema-on-production
+
+const assert = require('assert');
+const path = require('path');
+
+const { Sequelize, DataTypes } = require('sequelize');
+
+(async () => {
+{
+  const sequelize = new Sequelize({
+    dialect: 'sqlite',
+    storage: 'tmp.' + path.basename(__filename) + '.sqlite',
+  });
+  const IntegerNames = sequelize.define('IntegerNames', {
+    value: { type: DataTypes.INTEGER, },
+    name: { type: DataTypes.STRING, },
+  }, {});
+  await IntegerNames.sync({force: true})
+  await IntegerNames.create({value: 2, name: 'two'});
+  await IntegerNames.create({value: 3, name: 'three'});
+  await sequelize.close();
+}
+
+// Alter by adding column..
+{
+  const sequelize = new Sequelize({
+    dialect: 'sqlite',
+    storage: 'tmp.' + path.basename(__filename) + '.sqlite',
+  });
+  const IntegerNames = sequelize.define('IntegerNames', {
+    value: { type: DataTypes.INTEGER, },
+    name: { type: DataTypes.STRING, },
+    nameEs: { type: DataTypes.STRING, },
+  }, {});
+  await IntegerNames.sync({alter: true})
+  await IntegerNames.create({value: 5, name: 'five' , nameEs: 'cinco'});
+  await IntegerNames.create({value: 7, name: 'seven', nameEs: 'siete'});
+  const integerNames = await IntegerNames.findAll({
+    order: [['value', 'ASC']],
+  });
+  assert(integerNames[0].value  === 2);
+  assert(integerNames[0].name   === 'two');
+  assert(integerNames[0].nameEs === null);
+  assert(integerNames[1].name   === 'three');
+  assert(integerNames[1].nameEs === null);
+  assert(integerNames[2].name   === 'five');
+  assert(integerNames[2].nameEs === 'cinco');
+  assert(integerNames[3].name   === 'seven');
+  assert(integerNames[3].nameEs === 'siete');
+  await sequelize.close();
+}
+
+// Alter by removing column. undefined instead of null,
+// because the values really aren't present in the database anymore.
+{
+  const sequelize = new Sequelize({
+    dialect: 'sqlite',
+    storage: 'tmp.' + path.basename(__filename) + '.sqlite',
+  });
+  const IntegerNames = sequelize.define('IntegerNames', {
+    value: { type: DataTypes.INTEGER, },
+    name: { type: DataTypes.STRING, },
+  }, {});
+  await IntegerNames.sync({alter: true})
+  const integerNames = await IntegerNames.findAll({
+    order: [['value', 'ASC']],
+  });
+  assert(integerNames[0].value  === 2);
+  assert(integerNames[0].name   === 'two');
+  assert(integerNames[0].nameEs === undefined);
+  assert(integerNames[1].name   === 'three');
+  assert(integerNames[1].nameEs === undefined);
+  assert(integerNames[2].name   === 'five');
+  assert(integerNames[2].nameEs === undefined);
+  assert(integerNames[3].name   === 'seven');
+  assert(integerNames[3].nameEs === undefined);
+  await sequelize.close();
+}
+
+// Alter a type.
+// Hmm, docs suggest data would get dropped, but I only see typecast without alter.drop,
+// so shy does it work still?. sqlite from CLI does confirm that it is now a VARCHAR(255)
+// column.
+{
+  const sequelize = new Sequelize({
+    dialect: 'sqlite',
+    storage: 'tmp.' + path.basename(__filename) + '.sqlite',
+  });
+  const IntegerNames = sequelize.define('IntegerNames', {
+    value: { type: DataTypes.STRING, },
+    name: { type: DataTypes.STRING, },
+  }, {});
+  await IntegerNames.sync({alter: true})
+  const integerNames = await IntegerNames.findAll({
+    order: [['value', 'ASC']],
+  });
+  assert(integerNames[0].value === '2');
+  assert(integerNames[0].name  === 'two');
+  assert(integerNames[1].value === '3');
+  assert(integerNames[1].name  === 'three');
+  assert(integerNames[2].value === '5');
+  assert(integerNames[2].name  === 'five');
+  assert(integerNames[3].value === '7');
+  assert(integerNames[3].name  === 'seven');
+  await sequelize.close();
+}
+
+})();