Search notes:
SQL: NULLIF
The expression
nullif(p
1
, p
2
)
evaluates to
null
if
p
1
== p
2
, otherwise to
p
1
.
nullif(p
1
, p
2
)
is equivalent to the following
case
expression:
case when p₁ = p₂ then null else p₁ end
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