support ALTER TABLE ADD ... AFTER.

Patch from Andrew Gaul argaul@gmail.com
Fixes issue 401.

h2/src/docsrc/html/changelog.html

@@ -24,6 +24,7 @@ Change Log
 </li><li>MVStore: unified exception handling; the version is included in the messages.
 </li><li>MVStore: old data is now retained for 45 seconds by default.
 </ul><li>MVStore: compress is now disabled by default, and can be enabled on request.
+</ul><li>Support ALTER TABLE ADD ... AFTER. Patch from Andrew Gaul argaul@gmail.com. Fixes issue 401.
 </li></ul>
 
 <h2>Version 1.3.170 (2012-11-30)</h2>

h2/src/main/org/h2/command/Parser.java

@@ -4987,6 +4987,8 @@ public class Parser {
             columnsToAdd.add(column);
             if (readIf("BEFORE")) {
                 command.setAddBefore(readColumnIdentifier());
+            } else if (readIf("AFTER")) {
+                command.setAddAfter(readColumnIdentifier());
             }
         }
         command.setNewColumns(columnsToAdd);

h2/src/main/org/h2/command/ddl/AlterTableAlterColumn.java

@@ -54,6 +54,7 @@ public class AlterTableAlterColumn extends SchemaCommand {
     private Expression defaultExpression;
     private Expression newSelectivity;
     private String addBefore;
+    private String addAfter;
     private boolean ifNotExists;
     private ArrayList<Column> columnsToAdd;
 
@@ -73,6 +74,10 @@ public class AlterTableAlterColumn extends SchemaCommand {
         this.addBefore = before;
     }
 
+    public void setAddAfter(String after) {
+        this.addAfter = after;
+    }
+
     public int update() {
         session.commit(true);
         Database db = session.getDatabase();
@@ -270,10 +275,12 @@ public class AlterTableAlterColumn extends SchemaCommand {
             newColumns.remove(position);
         } else if (type == CommandInterface.ALTER_TABLE_ADD_COLUMN) {
             int position;
-            if (addBefore == null) {
-                position = columns.length;
-            } else {
+            if (addBefore != null) {
                 position = table.getColumn(addBefore).getColumnId();
+            } else if (addAfter != null) {
+                position = table.getColumn(addAfter).getColumnId() + 1;
+            } else {
+                position = columns.length;
             }
             for (Column column : columnsToAdd) {
                 newColumns.add(position++, column);

h2/src/main/org/h2/res/help.csv

@@ -80,7 +80,7 @@ ALTER SEQUENCE sequenceName [ RESTART WITH long ] [ INCREMENT BY long ]
 Changes the next value and the increment of a sequence."
 "Commands (DDL)","ALTER TABLE ADD","
 ALTER TABLE tableName ADD [ COLUMN ]
-{ [ IF NOT EXISTS ] columnDefinition [ BEFORE columnName ]
+{ [ IF NOT EXISTS ] columnDefinition [ BEFORE columnName | AFTER columnName ]
     | ( { columnDefinition } [,...] ) }
 ","
 Adds a new column to a table."

h2/src/test/org/h2/test/db/TestAlter.java

@@ -7,6 +7,7 @@
 package org.h2.test.db;
 
 import java.sql.Connection;
+import java.sql.DatabaseMetaData;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -42,6 +43,8 @@ public class TestAlter extends TestBase {
         testAlterTableAddColumnIfNotExists();
         testAlterTableAddMultipleColumns();
         testAlterTableAlterColumn2();
+        testAlterTableAddColumnBefore();
+        testAlterTableAddColumnAfter();
         conn.close();
         deleteDb("alter");
     }
@@ -146,6 +149,34 @@ public class TestAlter extends TestBase {
         stat.execute("drop table t");
     }
 
+    // column and field names must be upper-case due to getMetaData sensitivity
+    private void testAlterTableAddColumnBefore() throws SQLException {
+        stat.execute("create table T(X varchar)");
+        stat.execute("alter table T add Y int before X");
+        DatabaseMetaData dbmeta = conn.getMetaData();
+        ResultSet rs = dbmeta.getColumns(null, null, "T", null);
+        assertTrue(rs.next());
+        assertEquals("Y", rs.getString("COLUMN_NAME"));
+        assertTrue(rs.next());
+        assertEquals("X", rs.getString("COLUMN_NAME"));
+        assertFalse(rs.next());
+        stat.execute("drop table T");
+    }
+
+    // column and field names must be upper-case due to getMetaData sensitivity
+    private void testAlterTableAddColumnAfter() throws SQLException {
+        stat.execute("create table T(X varchar)");
+        stat.execute("alter table T add Y int after X");
+        DatabaseMetaData dbmeta = conn.getMetaData();
+        ResultSet rs = dbmeta.getColumns(null, null, "T", null);
+        assertTrue(rs.next());
+        assertEquals("X", rs.getString("COLUMN_NAME"));
+        assertTrue(rs.next());
+        assertEquals("Y", rs.getString("COLUMN_NAME"));
+        assertFalse(rs.next());
+        stat.execute("drop table T");
+    }
+
     private void testAlterTableAlterColumn2() throws SQLException {
         // ensure that increasing a VARCHAR columns length takes effect because
         // we optimize this case