feat: add syntax sugar

Signed-off-by: Andreas Reichel <andreas@manticore-projects.com>

Author: manticore-projects

src/main/java/net/sf/jsqlparser/expression/IntervalExpression.java

@@ -28,6 +28,13 @@ public IntervalExpression(boolean intervalKeyword) {
         this.intervalKeyword = intervalKeyword;
     }
 
+    public IntervalExpression(int value, String type) {
+        this.parameter = null;
+        this.intervalKeyword = true;
+        this.expression = new LongValue(value);
+        this.intervalType = type;
+    }
+
     public boolean isUsingIntervalKeyword() {
         return intervalKeyword;
     }