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Last data update: 2014.03.03

R: Parse interpolated variables from SQL.

sqlParseVariables

R Documentation

Parse interpolated variables from SQL.

Description

If you're implementing a backend that uses non-ANSI quoting or commenting rules, you'll need to implement a method for sqlParseVariables that calls sqlParseVariablesImpl with the appropriate quote and comment specifications.

Usage

sqlParseVariables(con, sql, ...)

## S4 method for signature 'DBIConnection'
sqlParseVariables(con, sql, ...)

sqlCommentSpec(start, end, endRequired)

sqlQuoteSpec(start, end, escape = "", doubleEscape = TRUE)

sqlParseVariablesImpl(sql, quotes, comments)

Arguments

`sql`	SQL to parse (a character vector of length 1)
`start, end`	Start and end characters for quotes and comments
`endRequired`	Is the ending character of a comment required?
`escape`	What character can be used to escape quoting characters? Defaults to `""`, i.e. nothing.
`doubleEscape`	Can quoting characters be escaped by doubling them? Defaults to `TRUE`.
`quotes`	A list of `QuoteSpec` calls defining the quoting specification.
`comments`	A list of `CommentSpec` calls defining the commenting specification.

Examples

# Use [] for quoting and no comments
sqlParseVariablesImpl("[?a]",
  list(sqlQuoteSpec("[", "]", "\", FALSE)),
  list()
)

# Standard quotes, use # for commenting
sqlParseVariablesImpl("# ?a\n?b",
  list(sqlQuoteSpec("'", "'"), sqlQuoteSpec('"', '"')),
  list(sqlCommentSpec("#", "\n", FALSE))
)

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
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> library(DBI)
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/DBI/sqlParseVariables.Rd_%03d_medium.png", width=480, height=480)
> ### Name: sqlParseVariables
> ### Title: Parse interpolated variables from SQL.
> ### Aliases: sqlCommentSpec sqlParseVariables
> ###   sqlParseVariables,DBIConnection-method sqlParseVariablesImpl
> ###   sqlQuoteSpec
> ### Keywords: internal
> 
> ### ** Examples
> 
> # Use [] for quoting and no comments
> sqlParseVariablesImpl("[?a]",
+   list(sqlQuoteSpec("[", "]", "\", FALSE)),
+   list()
+ )
$start
integer(0)

$end
integer(0)

> 
> # Standard quotes, use # for commenting
> sqlParseVariablesImpl("# ?a\n?b",
+   list(sqlQuoteSpec("'", "'"), sqlQuoteSpec('"', '"')),
+   list(sqlCommentSpec("#", "\n", FALSE))
+ )
$start
integer(0)

$end
integer(0)

> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>