diff options
author | Adam Chlipala <adam@chlipala.net> | 2011-02-03 21:04:12 -0500 |
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committer | Adam Chlipala <adam@chlipala.net> | 2011-02-03 21:04:12 -0500 |
commit | b9d68f77db05b61f29dba9a5680d4875b95e0e2f (patch) | |
tree | 0d7561a584be03f1fbd5a3297a101e3c54bf7ba9 /doc | |
parent | b0cff3eab8287308dde58dd7e288e654b9fa7b5b (diff) |
Subqueries may always return NULL
Diffstat (limited to 'doc')
-rw-r--r-- | doc/manual.tex | 4 |
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. |