add ValidationVisitor showcase

JSQLParser#1005

src/main/java/net/sf/jsqlparser/util/validation/DatabaseType.java

@@ -0,0 +1,23 @@
+package net.sf.jsqlparser.util.validation;
+
+/**
+ * <p>
+ * The DatabaseType is named like the identifier used within the
+ * jdbc-connection-url, this may change in future, therefore use
+ * {@link #get(String)} to retrieve the {@link DatabaseType}.
+ * </p>
+ */
+public enum DatabaseType {
+
+    oracle, mysql, sqlserver;
+
+    /**
+     * @param jdbcIdentifier - the database-identifier-part of jdbc-url
+     * @return the {@link DatabaseType}
+     * @throws IllegalArgumentException - if the specified jdbcIdentifier cannot be mapped to a {@link DatabaseType}
+     */
+    public static DatabaseType get(String jdbcIdentifier) {
+        return DatabaseType.valueOf(jdbcIdentifier);
+    }
+
+}