print decimal as long if scale is zero

optimize numeric and decimal displaying

add unit test case for print simple decimal

close the cursor

test/data/create_simple_decimal.sql

@@ -0,0 +1,5 @@
+create table customer (
+"CUST_ID" INTEGER not null,
+"USER_ID" DECIMAL(18,0) not null,
+primary key ("CUST_ID")
+);

test/data/insert_simple_decimal.sql

@@ -0,0 +1 @@
+insert into CUSTOMER (CUST_ID, USER_ID) values (1, 12345);