# HG changeset patch
# User Adam Chlipala <adamc@hcoop.net>
# Date 1228663463 18000
# Node ID f31aa2a3a72d8f243227839cb1dc8182f4bad70a
# Parent  4154b4dc62c61fa3713b44c5297c289243706c52
DML

diff -r 4154b4dc62c6 -r f31aa2a3a72d doc/manual.tex
--- a/doc/manual.tex	Sun Dec 07 10:02:04 2008 -0500
+++ b/doc/manual.tex	Sun Dec 07 10:24:23 2008 -0500
@@ -981,6 +981,14 @@
   \hspace{.1in} \to \mt{sql\_query} \; \mt{selectedFields} \; \mt{selectedExps}
 \end{array}$$
 
+Queries are used by folding over their results inside transactions.
+$$\begin{array}{l}
+  \mt{val} \; \mt{query} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \lambda [\mt{tables} \sim \mt{exps}] \Rightarrow \mt{state} ::: \mt{Type} \to \mt{sql\_query} \; \mt{tables} \; \mt{exps} \\
+  \hspace{.1in} \to (\$(\mt{exps} \rc \mt{fold} \; (\lambda \mt{nm} \; (\mt{fields} :: \{\mt{Type}\}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \$\mt{fields}] \rc \mt{acc}) \; [] \; \mt{tables}) \\
+  \hspace{.2in} \to \mt{state} \to \mt{transaction} \; \mt{state}) \\
+  \hspace{.1in} \to \mt{state} \to \mt{transaction} \; \mt{state}
+\end{array}$$
+
 Most of the complexity of the query encoding is in the type $\mt{sql\_query1}$, which includes simple queries and derived queries based on relational operators.  Constructor arguments respectively specify the tables we select from, the subset of fields that we keep from each table for the result rows, and the extra expressions that we select.
 $$\begin{array}{l}
   \mt{con} \; \mt{sql\_query1} :: \{\{\mt{Type}\}\} \to \{\{\mt{Type}\}\} \to \{\mt{Type}\} \to \mt{Type} \\
@@ -1151,4 +1159,32 @@
   \mt{val} \; \mt{sql\_offset} : \mt{int} \to \mt{sql\_offset}
 \end{array}$$
 
+
+\subsubsection{DML}
+
+The Ur/Web library also includes an embedding of a fragment of SQL's DML, the Data Manipulation Language, for modifying database tables.  Any piece of DML may be executed in a transaction.
+
+$$\begin{array}{l}
+  \mt{type} \; \mt{dml} \\
+  \mt{val} \; \mt{dml} : \mt{dml} \to \mt{transaction} \; \mt{unit}
+\end{array}$$
+
+Properly-typed records may be used to form $\mt{INSERT}$ commands.
+$$\begin{array}{l}
+  \mt{val} \; \mt{insert} : \mt{fields} ::: \{\mt{Type}\} \to \mt{sql\_table} \; \mt{fields} \\
+  \hspace{.1in} \to \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{t} :: \mt{Type}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_exp} \; [] \; [] \; [] \; \mt{t}] \rc \mt{acc}) \; [] \; \mt{fields}) \to \mt{dml}
+\end{array}$$
+
+An $\mt{UPDATE}$ command is formed from a choice of which table fields to leave alone and which to change, along with an expression to use to compute the new value of each changed field and a $\mt{WHERE}$ clause.
+$$\begin{array}{l}
+  \mt{val} \; \mt{update} : \mt{unchanged} ::: \{\mt{Type}\} \to \mt{changed} :: \{\mt{Type}\} \to \lambda [\mt{changed} \sim \mt{unchanged}] \\
+  \hspace{.1in} \Rightarrow \$(\mt{fold} \; (\lambda \mt{nm} \; (\mt{t} :: \mt{Type}) \; \mt{acc} \; [[\mt{nm}] \sim \mt{acc}] \Rightarrow [\mt{nm} = \mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; [] \; \mt{t}] \rc \mt{acc}) \; [] \; \mt{changed}) \\
+  \hspace{.1in} \to \mt{sql\_table} \; (\mt{changed} \rc \mt{unchanged}) \to \mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; [] \; \mt{bool} \to \mt{dml}
+\end{array}$$
+
+A $\mt{DELETE}$ command is formed from a table and a $\mt{WHERE}$ clause.
+$$\begin{array}{l}
+  \mt{val} \; \mt{delete} : \mt{fields} ::: \{\mt{Type}\} \to \mt{sql\_table} \; \mt{fields} \to \mt{sql\_exp} \; [\mt{T} = \mt{fields}] \; [] \; [] \; \mt{bool} \to \mt{dml}
+\end{array}$$
+
 \end{document}
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