translate_sql {dbplyr} | R Documentation |

Translate an expression to sql

translate_sql( ..., con = NULL, vars = character(), vars_group = NULL, vars_order = NULL, vars_frame = NULL, window = TRUE ) translate_sql_( dots, con = NULL, vars_group = NULL, vars_order = NULL, vars_frame = NULL, window = TRUE, context = list() )

`..., dots` |
Expressions to translate. |

`con` |
An optional database connection to control the details of
the translation. The default, |

`vars` |
Deprecated. Now call |

`vars_group, vars_order, vars_frame` |
Parameters used in the |

`window` |
Use |

`context` |
Use to carry information for special translation cases. For example, MS SQL needs a different conversion for is.na() in WHERE vs. SELECT clauses. Expects a list. |

The base translator, `base_sql`

, provides custom mappings for for
commonly used base functions including logical (`!`

, `&`

, `|`

),
arithmetic (`^`

), and comparison (`!=`

) operators, as well as common
summary (`mean()`

, `var()`

) and manipulation functions.

All other functions will be preserved as is. R's infix functions
(e.g. `%like%`

) will be converted to their SQL equivalents (e.g. `LIKE`

).
You can use this to access SQL string concatenation: `||`

is mapped to
`OR`

, but `%||%`

is mapped to `||`

. To suppress this behaviour, and force
errors immediately when dplyr doesn't know how to translate a function it
encounters, using set the `dplyr.strict_sql`

option to `TRUE`

.

You can also use `sql()`

to insert a raw sql string.

The SQLite variant currently only adds one additional function: a mapping
from `sd()`

to the SQL aggregation function `STDEV`

.

# Regular maths is translated in a very straightforward way translate_sql(x + 1) translate_sql(sin(x) + tan(y)) # Note that all variable names are escaped translate_sql(like == "x") # In ANSI SQL: "" quotes variable _names_, '' quotes strings # Logical operators are converted to their sql equivalents translate_sql(x < 5 & !(y >= 5)) # xor() doesn't have a direct SQL equivalent translate_sql(xor(x, y)) # If is translated into case when translate_sql(if (x > 5) "big" else "small") # Infix functions are passed onto SQL with % removed translate_sql(first %like% "Had%") translate_sql(first %is% NA) translate_sql(first %in% c("John", "Roger", "Robert")) # And be careful if you really want integers translate_sql(x == 1) translate_sql(x == 1L) # If you have an already quoted object, use translate_sql_: x <- quote(y + 1 / sin(t)) translate_sql_(list(x), con = simulate_dbi()) # Windowed translation -------------------------------------------- # Known window functions automatically get OVER() translate_sql(mpg > mean(mpg)) # Suppress this with window = FALSE translate_sql(mpg > mean(mpg), window = FALSE) # vars_group controls partition: translate_sql(mpg > mean(mpg), vars_group = "cyl") # and vars_order controls ordering for those functions that need it translate_sql(cumsum(mpg)) translate_sql(cumsum(mpg), vars_order = "mpg")

[Package *dbplyr* version 2.1.1 Index]