Show SQL for database

Also improvements to the SQL for tables and views.

pglablib/catalog/PgServerObject.cpp

@@ -94,10 +94,20 @@ QString PgServerObject::aclAllPattern() const
 
 QString PgServerObject::dropSql() const
 {
-	return {};
+    return "DROP " % typeName() % " " % fullyQualifiedQuotedObjectName() % ";";
 }
 
 QString PgServerObject::createSql() const
 {
-	return {};
+    return {};
 }
+
+QString PgServerObject::commentSql() const
+{
+    if (description.isEmpty())
+        return {};
+
+    return "COMMENT ON " + typeName() + " " + fullyQualifiedQuotedObjectName()
+                + " IS " + escapeLiteral(description) + ";";
+}
+