Mercurial > urweb
comparison doc/manual.tex @ 1683:be1ed46d73e2
Mention convention for parens in selected expressions
| author | Adam Chlipala <adam@chlipala.net> |
|---|---|
| date | Fri, 03 Feb 2012 08:30:56 -0500 |
| parents | 1a8f7d667c00 |
| children | 9dd8d47c3e58 |
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| 1682:ac141fbb313a | 1683:be1ed46d73e2 |
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| 2176 \textrm{SQL integer} & N &::=& n \mid \{e\} \\ | 2176 \textrm{SQL integer} & N &::=& n \mid \{e\} \\ |
| 2177 \end{array}$$ | 2177 \end{array}$$ |
| 2178 | 2178 |
| 2179 Additionally, an SQL expression may be inserted into normal Ur code with the syntax $(\mt{SQL} \; E)$ or $(\mt{WHERE} \; E)$. Similar shorthands exist for other nonterminals, with the prefix $\mt{FROM}$ for $\mt{FROM}$ items and $\mt{SELECT1}$ for pre-queries. | 2179 Additionally, an SQL expression may be inserted into normal Ur code with the syntax $(\mt{SQL} \; E)$ or $(\mt{WHERE} \; E)$. Similar shorthands exist for other nonterminals, with the prefix $\mt{FROM}$ for $\mt{FROM}$ items and $\mt{SELECT1}$ for pre-queries. |
| 2180 | 2180 |
| 2181 Unnamed expression columns in $\mt{SELECT}$ clauses are assigned consecutive natural numbers, starting with 1. | 2181 Unnamed expression columns in $\mt{SELECT}$ clauses are assigned consecutive natural numbers, starting with 1. Any expression in a $p$ position that is enclosed in parentheses is treated as an expression column, rather than a column pulled directly out of a table, even if it is only a field projection. (This distinction affects the record type used to describe query results.) |
| 2182 | 2182 |
| 2183 \subsubsection{DML} | 2183 \subsubsection{DML} |
| 2184 | 2184 |
| 2185 DML commands $D$ are added to the rules for expressions $e$. | 2185 DML commands $D$ are added to the rules for expressions $e$. |
| 2186 | 2186 |