###############################################
#                                             #
#   Prepared Statements test on               #
#   "nested sets" representing hierarchies    #
#                                             #
###############################################

# Source: http://kris.koehntopp.de/artikel/sql-self-references (dated 1999)
# Source: http://dbmsmag.com/9603d06.html (dated 1996)

use test;

drop table if exists personnel;

# "Nested Set": This table represents an employee list with a hierarchy tree.
# The tree is not modeled by "parent" links but rather by showing the "left"
# and "right" border of any person's "region". By convention, "l" < "r".
# As it is a tree, these "regions" of two persons A and B are either disjoint,
# or A's region is completely contained in B's (B is A's boss), or vice versa.
# See the references for more info.

create table personnel  (
  id     INTEGER AUTO_INCREMENT PRIMARY KEY,
  emp    CHAR(10) NOT NULL,
  salary DECIMAL(6,2) NOT NULL,
  l INTEGER NOT NULL,
  r INTEGER NOT NULL);

prepare st_ins from 'insert into personnel set emp = ?, salary = ?, l = ?, r = ?';

# Initial employee list:
# Jerry ( Bert ( ) Chuck ( Donna ( ) Eddie ( ) Fred ( ) ) )
set @arg_nam= 'Jerry'; set @arg_sal= 1000; set @arg_l= 1; set @arg_r= 12;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;
set @arg_nam= 'Bert';  set @arg_sal=  900; set @arg_l= 2; set @arg_r=  3;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;
set @arg_nam= 'Chuck'; set @arg_sal=  900; set @arg_l= 4; set @arg_r= 11;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;
set @arg_nam= 'Donna'; set @arg_sal=  800; set @arg_l= 5; set @arg_r=  6;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;
set @arg_nam= 'Eddie'; set @arg_sal=  700; set @arg_l= 7; set @arg_r=  8;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;
set @arg_nam= 'Fred';  set @arg_sal=  600; set @arg_l= 9; set @arg_r= 10;
execute st_ins using @arg_nam, @arg_sal, @arg_l, @arg_r ;

select * from personnel;

# Three successive raises, each one is 100 units for managers, 10 percent for others.
prepare st_raise_base from 'update personnel set salary = salary * ( 1 + ? ) where r - l = 1';
prepare st_raise_mgr  from 'update personnel set salary = salary + ? where r - l > 1';
let $1= 3;
set @arg_percent= .10;
set @arg_amount= 100;
while ($1)
{
  execute st_raise_base using @arg_percent;
  execute st_raise_mgr  using @arg_amount;
  dec $1;
}

select * from personnel;

drop table personnel;