Create simple query builder in DAO classes

api/src/main/java/com/bartlomiejpluta/base/lib/db/Relop.java

@@ -0,0 +1,17 @@
+package com.bartlomiejpluta.base.lib.db;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public enum Relop {
+   EQ("="),
+   NE("<>"),
+   GT(">"),
+   GE(">="),
+   LT("<"),
+   LE("<=");
+
+   @Getter
+   private final String op;
+}