Subqueries may always return NULL

1 files changed, 2 insertions, 2 deletions

diff --git a/doc/manual.tex b/doc/manual.tex
index ad6edeb9..c39d92df 100644
--- a/doc/manual.tex
+++ b/doc/manual.tex
@@ -1726,8 +1726,8 @@ $$\begin{array}{l}
 Any SQL query that returns single columns may be turned into a subquery expression.
 
 $$\begin{array}{l}
-\mt{val} \; \mt{sql\_subquery} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{agg} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \mt{nm} ::: \mt{Name} \to \mt{t} ::: \mt{Type} \\
-\hspace{.1in} \to \mt{sql\_query} \; \mt{tables} \; \mt{agg} \; [\mt{nm} = \mt{t}] \to \mt{sql\_exp} \; \mt{tables} \; \mt{agg} \; \mt{exps} \; \mt{t}
+\mt{val} \; \mt{sql\_subquery} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{agg} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \mt{nm} ::: \mt{Name} \to \mt{t} ::: \mt{Type} \to \mt{nt} ::: \mt{Type} \\
+\hspace{.1in} \to \mt{nullify} \; \mt{t} \; \mt{nt} \to \mt{sql\_query} \; \mt{tables} \; \mt{agg} \; [\mt{nm} = \mt{t}] \to \mt{sql\_exp} \; \mt{tables} \; \mt{agg} \; \mt{exps} \; \mt{nt}
 \end{array}$$
 
 \texttt{FROM} clauses are specified using a type family, whose arguments are the free table variables and the table variables bound by this clause.