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author | 2011-10-20 09:27:37 -0400 | |
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committer | 2011-10-20 09:27:37 -0400 | |
commit | eb8b1f13bd0b50318f553fddb056590236fcf6e1 (patch) | |
tree | 18f09b71f3b8518d707609cdfa864637003254b5 /doc/manual.tex | |
parent | af7d014dac8b18d782e80ee2867515aad8cad222 (diff) |
Some notes on 'T' for update/delete combinators
Diffstat (limited to 'doc/manual.tex')
-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 541dd96b..872dca93 100644 --- a/doc/manual.tex +++ b/doc/manual.tex @@ -1870,14 +1870,14 @@ $$\begin{array}{l} \hspace{.1in} \to \$(\mt{map} \; (\mt{sql\_exp} \; [] \; [] \; []) \; \mt{fields}) \to \mt{dml} \end{array}$$ -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. +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. Note that, in the table environment applied to expressions, the table being updated is hardcoded at the name $\mt{T}$. The parsing extension for $\mt{UPDATE}$ will elaborate all table-free field references to use table variable $\mt{T}$. $$\begin{array}{l} \mt{val} \; \mt{update} : \mt{unchanged} ::: \{\mt{Type}\} \to \mt{changed} :: \{\mt{Type}\} \to [\mt{changed} \sim \mt{unchanged}] \\ \hspace{.1in} \Rightarrow \$(\mt{map} \; (\mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; []) \; \mt{changed}) \\ \hspace{.1in} \to \mt{sql\_table} \; (\mt{changed} \rc \mt{unchanged}) \to \mt{sql\_exp} \; [\mt{T} = \mt{changed} \rc \mt{unchanged}] \; [] \; [] \; \mt{bool} \to \mt{dml} \end{array}$$ -A $\mt{DELETE}$ command is formed from a table and a $\mt{WHERE}$ clause. +A $\mt{DELETE}$ command is formed from a table and a $\mt{WHERE}$ clause. The above use of $\mt{T}$ is repeated. $$\begin{array}{l} \mt{val} \; \mt{delete} : \mt{fields} ::: \{\mt{Type}\} \to \mt{sql\_table} \; \mt{fields} \to \mt{sql\_exp} \; [\mt{T} = \mt{fields}] \; [] \; [] \; \mt{bool} \to \mt{dml} \end{array}$$ |