fixes #984

Author: wumpz

src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java

@@ -45,6 +45,15 @@ public class AlterExpression {
 
     private List<ConstraintState> constraints;
     private List<String> parameters;
+    private String commentText;
+
+    public String getCommentText() {
+        return commentText;
+    }
+
+    public void setCommentText(String commentText) {
+        this.commentText = commentText;
+    }
 
     public AlterOperation getOperation() {
         return operation;
@@ -116,7 +125,7 @@ public void addColDataType(ColumnDataType columnDataType) {
         }
         colDataTypeList.add(columnDataType);
     }
-    
+
     public void addColDropNotNull(ColumnDropNotNull columnDropNotNull) {
         if (columnDropNotNullList == null) {
             columnDropNotNullList = new ArrayList<ColumnDropNotNull>();
@@ -242,7 +251,12 @@ public String toString() {
 
         b.append(operation).append(" ");
 
-        if (columnName != null) {
+        if (commentText != null) {
+            if (columnName != null) {
+                b.append(columnName).append(" COMMENT ");
+            }
+            b.append(commentText);
+        } else if (columnName != null) {
             b.append("COLUMN ");
             if (operation == AlterOperation.RENAME) {
                 b.append(columnOldName).append(" TO ");
@@ -263,7 +277,7 @@ public String toString() {
             if (colDataTypeList.size() > 1) {
                 b.append(")");
             }
-        } else if ( getColumnDropNotNullList() != null) {
+        } else if (getColumnDropNotNullList() != null) {
             if (operation == AlterOperation.CHANGE) {
                 if (optionalSpecifier != null) {
                     b.append(optionalSpecifier).append(" ");
@@ -325,6 +339,7 @@ public String toString() {
     }
 
     public final static class ColumnDataType extends ColumnDefinition {
+
         private final boolean withType;
 
         public ColumnDataType(String columnName, boolean withType, ColDataType colDataType, List<String> columnSpecs) {
@@ -358,8 +373,8 @@ public boolean isWithNot() {
 
         @Override
         public String toString() {
-            return columnName + " DROP" +
-                     (withNot ? " NOT " : " ") + "NULL";
+            return columnName + " DROP"
+                    + (withNot ? " NOT " : " ") + "NULL";
         }
     }
 }

src/main/java/net/sf/jsqlparser/statement/alter/AlterOperation.java

@@ -10,5 +10,5 @@
 package net.sf.jsqlparser.statement.alter;
 
 public enum AlterOperation {
-    ADD, ALTER, DROP, MODIFY, CHANGE, ALGORITHM, RENAME;
+    ADD, ALTER, DROP, MODIFY, CHANGE, ALGORITHM, RENAME, COMMENT;
 }