The Codeless Code: Case 171 Initial Conditions
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The nun Hwídah was summoned to the offices of master
Banzen. She found the master waiting with his apprentice
Djishin in attendance.
Banzen said, “A happy day for you, little nun! Since you
take such pleasure in learning hidden truths and seeing
guilty parties corrected, I have an entertaining task for
you.”
“I serve at the pleasure of the Temple, not my own,” Hwídah
replied with a dutiful bow. But her stomach was already
clenched; for no doubt this was the start of her punishment
for trespassing on forbidden Temple ground.
“An infrequent but stubborn error has plagued the Elephant's
Footprint Clan for some time now,” said the master as he
handed the nun a printout. “Our database logs show this
malformed SQL query, yet a thorough search of our code base
reveals no such query anywhere. Find the source. I give you
one week.”
Hwídah studied the paper. “A few minutes should suffice. May
I borrow the master’s terminal?”
Banzen’s eyebrows shot up. He exchanged glances with his
apprentice, then slid his laptop toward the nun.
Hwídah consulted the printout, typed something, scrutinized
the screen, consulted the printout again, and so on several
times over. “There,” she said finally, turning the screen
around. The cursor was indeed hovering over a SQL fragment
with a missing right parenthesis. “If I return to my
workstation, I can trace this code to its consumers and
reproduce the error seen in the logs. Then we may repair the
defect with confidence.”
“Go,” said Banzen to Hwídah. To his apprentice he said:
“Observe.”
As the pair walked to Hwídah’s cubicle, Djishin whispered,
“The speed of your diagnosis was surprising.”
“A simple matter,” said Hwídah, handing the printout to the
monk. “The malformed query begins with WHERE 1=1. That has
the stink of dynamically-generated SQL—for although the
initial condition is trivial, its TRUE value allows a
developer to append any number of real conditions as simple
AND clauses. I have used this technique myself when
implementing search forms with optional fields. Once I
recognized it, I merely searched our code for the individual
AND clauses.”
“You misunderstand me,” said Djishin. “I was not surprised
that you were able to solve it immediately; I was surprised
that you did so despite being given a full week. That has
the stink of ambition—for although this initial problem was
trivial, your ready truthfulness now allows my master to
entrust you with any number of real problems.”
Hwídah sighed. “It is just as well. If I had pretended that
this problem was difficult enough to merit days of effort,
Banzen would have thought me either deceitful or
incompetent. Neither would sit well with me. That is what he
truly wished to discover.”
Djishin nodded. “Sometimes a test serves a purpose because
the answer is so obvious.”
