# [dm](https://dm.cynkra.com/)

> Are you using multiple data frames or database tables in R? Organize
> them with dm.
>
> - Use it for data analysis today.
> - Build data models tomorrow.
> - Deploy the data models to your organization’s Relational Database
>   Management System (RDBMS) the day after.

## Overview

dm bridges the gap in the data pipeline between individual data frames
and relational databases. It’s a grammar of joined tables that provides
a consistent set of verbs for consuming, creating, and deploying
relational data models. For individual researchers, it broadens the
scope of datasets they can work with and how they work with them. For
organizations, it enables teams to quickly and efficiently create and
share large, complex datasets.

dm objects encapsulate relational data models constructed from local
data frames or lazy tables connected to an RDBMS. dm objects support the
full suite of dplyr data manipulation verbs along with additional
methods for constructing and verifying relational data models, including
key selection, key creation, and rigorous constraint checking. Once a
data model is complete, dm provides methods for deploying it to an
RDBMS. This allows it to scale from datasets that fit in memory to
databases with billions of rows.

## Features

dm makes it easy to bring an existing relational data model into your R
session. As the dm object behaves like a named list of tables it
requires little change to incorporate it within existing workflows. The
dm interface and behavior is modeled after dplyr, so you may already be
familiar with many of its verbs. dm also offers:

- visualization to help you understand relationships between entities
  represented by the tables
- simpler joins that “know” how tables are related, including a
  “flatten” operation that automatically follows keys and performs
  column name disambiguation
- consistency and constraint checks to help you understand (and fix) the
  limitations of your data

That’s just the tip of the iceberg. See [Getting
started](https://dm.cynkra.com/articles/dm.html) to hit the ground
running and explore all the features.

## Installation

The latest stable version of the {dm} package can be obtained from
[CRAN](https://CRAN.R-project.org/package=dm) with the command

``` r

install.packages("dm")
```

The latest development version of {dm} can be installed from R-universe:

``` r

# Enable repository from cynkra
options(
  repos = c(
    cynkra = "https://cynkra.r-universe.dev",
    CRAN = "https://cloud.r-project.org"
  )
)
# Download and install dm in R
install.packages('dm')
```

or from GitHub:

``` r

# install.packages("devtools")
devtools::install_github("cynkra/dm")
```

## Usage

Create a dm object (see [Getting
started](https://dm.cynkra.com/articles/dm.html) for details).

``` r

library(dm)
dm <- dm_nycflights13(table_description = TRUE)
dm
#> -- Metadata --------------------------------------------------------------------
#> Tables: `airlines`, `airports`, `flights`, `planes`, `weather`
#> Columns: 53
#> Primary keys: 4
#> Foreign keys: 4
```

dm is a named list of tables:

``` r

names(dm)
#> [1] "airlines" "airports" "flights"  "planes"   "weather"
nrow(dm$airports)
#> [1] 86
dm$flights %>%
  count(origin)
#> # A tibble: 3 × 2
#>   origin     n
#>   <chr>  <int>
#> 1 EWR      641
#> 2 JFK      602
#> 3 LGA      518
```

Visualize relationships at any time:

``` r

dm %>%
  dm_draw()
```

![](reference/figures/README-draw.svg)

Simple joins:

``` r

dm %>%
  dm_flatten_to_tbl(flights)
#> Renaming ambiguous columns: %>%
#>   dm_rename(flights, year.flights = year) %>%
#>   dm_rename(flights, month.flights = month) %>%
#>   dm_rename(flights, day.flights = day) %>%
#>   dm_rename(flights, hour.flights = hour) %>%
#>   dm_rename(airlines, name.airlines = name) %>%
#>   dm_rename(airports, name.airports = name) %>%
#>   dm_rename(planes, year.planes = year) %>%
#>   dm_rename(weather, year.weather = year) %>%
#>   dm_rename(weather, month.weather = month) %>%
#>   dm_rename(weather, day.weather = day) %>%
#>   dm_rename(weather, hour.weather = hour)
#> # A tibble: 1,761 × 48
#>    year.flights month.…¹ day.f…² dep_t…³ sched…⁴ dep_d…⁵ arr_t…⁶ sched…⁷ arr_d…⁸
#>           <int>    <int>   <int>   <int>   <int>   <dbl>   <int>   <int>   <dbl>
#>  1         2013        1      10       3    2359       4     426     437     -11
#>  2         2013        1      10      16    2359      17     447     444       3
#>  3         2013        1      10     450     500     -10     634     648     -14
#>  4         2013        1      10     520     525      -5     813     820      -7
#>  5         2013        1      10     530     530       0     824     829      -5
#>  6         2013        1      10     531     540      -9     832     850     -18
#>  7         2013        1      10     535     540      -5    1015    1017      -2
#>  8         2013        1      10     546     600     -14     645     709     -24
#>  9         2013        1      10     549     600     -11     652     724     -32
#> 10         2013        1      10     550     600     -10     649     703     -14
#> # ℹ 1,751 more rows
#> # ℹ abbreviated names: ¹​month.flights, ²​day.flights, ³​dep_time,
#> #   ⁴​sched_dep_time, ⁵​dep_delay, ⁶​arr_time, ⁷​sched_arr_time, ⁸​arr_delay
#> # ℹ 39 more variables: carrier <chr>, flight <int>, tailnum <chr>,
#> #   origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>,
#> #   hour.flights <dbl>, minute <dbl>, time_hour <dttm>, name.airlines <chr>,
#> #   name.airports <chr>, lat <dbl>, lon <dbl>, alt <dbl>, tz <dbl>, dst <chr>,
#> #   tzone <chr>, year.planes <int>, type <chr>, manufacturer <chr>,
#> #   model <chr>, engines <int>, seats <int>, speed <int>, engine <chr>,
#> #   year.weather <int>, month.weather <int>, day.weather <int>,
#> #   hour.weather <int>, temp <dbl>, dewp <dbl>, humid <dbl>, wind_dir <dbl>,
#> #   wind_speed <dbl>, wind_gust <dbl>, precip <dbl>, pressure <dbl>, …
```

Check consistency:

``` r

dm %>%
  dm_examine_constraints()
#> ! Unsatisfied constraints:
#> • Table `flights`: foreign key `tailnum` into table `planes`: values of `flights$tailnum` not in `planes$tailnum`: N725MQ (6), N537MQ (5), N722MQ (5), N730MQ (5), N736MQ (5), …
```

Learn more in the [Getting
started](https://dm.cynkra.com/articles/dm.html) article.

## Getting help

If you encounter a clear bug, please file an issue with a minimal
reproducible example on [GitHub](https://github.com/cynkra/dm/issues).
For questions and other discussion, please use
[community.rstudio.com](https://community.rstudio.com/).

# Package index

## Basic

Construct a `dm` object from data frames, see also
[`vignette("howto-dm-df")`](https://dm.cynkra.com/articles/howto-dm-df.md).

- [`dm()`](https://dm.cynkra.com/reference/dm.md)
  [`new_dm()`](https://dm.cynkra.com/reference/dm.md)
  [`is_dm()`](https://dm.cynkra.com/reference/dm.md)
  [`as_dm()`](https://dm.cynkra.com/reference/dm.md) : Data model class
- [`dm_validate()`](https://dm.cynkra.com/reference/dm_validate.md) :
  Validator

## Database

Construct a `dm` object from a database, see also
[`vignette("howto-dm-db")`](https://dm.cynkra.com/articles/howto-dm-db.md).

- [`dm_from_con()`](https://dm.cynkra.com/reference/dm_from_con.md) :
  Load a dm from a remote data source
- [`dm_get_con()`](https://dm.cynkra.com/reference/dm_get_con.md) : Get
  connection

## Tables and columns

Operate on the tables and columns stored in a `dm` object.

- [`dm_select_tbl()`](https://dm.cynkra.com/reference/dm_select_tbl.md)
  [`dm_rename_tbl()`](https://dm.cynkra.com/reference/dm_select_tbl.md)
  : Select and rename tables

- [`dm_get_tables()`](https://dm.cynkra.com/reference/dm_get_tables.md)
  : Get tables

- [`pull_tbl()`](https://dm.cynkra.com/reference/pull_tbl.md) : Retrieve
  a table

- [`dm_mutate_tbl()`](https://dm.cynkra.com/reference/dm_mutate_tbl.md)
  **\[experimental\]** :

  Update tables in a `dm`

- [`dm_nrow()`](https://dm.cynkra.com/reference/dm_nrow.md) : Number of
  rows

- [`dm_select()`](https://dm.cynkra.com/reference/dm_select.md) : Select
  columns

- [`dm_rename()`](https://dm.cynkra.com/reference/dm_rename.md) : Rename
  columns

## Primary keys

Primary keys uniquely identify rows in a table. A table can have at most
one primary key. See also
[`vignette("howto-dm-theory")`](https://dm.cynkra.com/articles/howto-dm-theory.md).

- [`dm_add_pk()`](https://dm.cynkra.com/reference/dm_add_pk.md) : Add a
  primary key

- [`dm_get_all_pks()`](https://dm.cynkra.com/reference/dm_get_all_pks.md)
  :

  Get all primary keys of a `dm` object

- [`dm_has_pk()`](https://dm.cynkra.com/reference/dm_has_pk.md) : Check
  for primary key

- [`dm_rm_pk()`](https://dm.cynkra.com/reference/dm_rm_pk.md) : Remove a
  primary key

## Unique keys

Unique keys are similar to primary keys. Each table can have at most one
record for each combination of values in a unique key. A table can have
more than one unique key.

- [`dm_add_uk()`](https://dm.cynkra.com/reference/dm_add_uk.md) : Add a
  unique key

- [`dm_get_all_uks()`](https://dm.cynkra.com/reference/dm_get_all_uks.md)
  :

  Get all unique keys of a `dm` object

- [`dm_rm_uk()`](https://dm.cynkra.com/reference/dm_rm_uk.md) : Remove a
  unique key

## Foreign keys

Foreign keys establish links between tables by pointing to a primary or
unique key in another table. See also
[`vignette("howto-dm-theory")`](https://dm.cynkra.com/articles/howto-dm-theory.md).

- [`dm_add_fk()`](https://dm.cynkra.com/reference/dm_add_fk.md) : Add
  foreign keys
- [`dm_get_all_fks()`](https://dm.cynkra.com/reference/dm_get_all_fks.md)
  : Get foreign key constraints
- [`dm_rm_fk()`](https://dm.cynkra.com/reference/dm_rm_fk.md) : Remove
  foreign keys

## Visualize

Show a `dm` object, see also
[`vignette("tech-dm-draw")`](https://dm.cynkra.com/articles/tech-dm-draw.md).

- [`dm_gui()`](https://dm.cynkra.com/reference/dm_gui.md)
  **\[experimental\]** : Shiny app for defining dm objects
- [`dm_draw()`](https://dm.cynkra.com/reference/dm_draw.md) : Draw a
  diagram of the data model
- [`dm_set_colors()`](https://dm.cynkra.com/reference/dm_set_colors.md)
  [`dm_get_colors()`](https://dm.cynkra.com/reference/dm_set_colors.md)
  [`dm_get_available_colors()`](https://dm.cynkra.com/reference/dm_set_colors.md)
  : Color in database diagrams
- [`dm_set_table_description()`](https://dm.cynkra.com/reference/dm_set_table_description.md)
  [`dm_get_table_description()`](https://dm.cynkra.com/reference/dm_set_table_description.md)
  [`dm_reset_table_description()`](https://dm.cynkra.com/reference/dm_set_table_description.md)
  : Add info about a dm's tables

## Deconstruct

Rip a `dm` object apart and put it together, see also
[`vignette("tech-dm-keyed")`](https://dm.cynkra.com/articles/tech-dm-keyed.md).

- [`dm_deconstruct()`](https://dm.cynkra.com/reference/dm_deconstruct.md)
  **\[experimental\]** : Create code to deconstruct a dm object

## Flatten

Combine multiple related tables, see also
[`vignette("tech-dm-join")`](https://dm.cynkra.com/articles/tech-dm-join.md).

- [`dm_flatten()`](https://dm.cynkra.com/reference/dm_flatten.md)
  **\[experimental\]** :

  Flatten a table in a `dm` by joining its parent tables

- [`dm_flatten_to_tbl()`](https://dm.cynkra.com/reference/dm_flatten_to_tbl.md)
  :

  Flatten a part of a `dm` into a wide table

- [`dm_disambiguate_cols()`](https://dm.cynkra.com/reference/dm_disambiguate_cols.md)
  : Resolve column name ambiguities

## Filter

Filter across multiple tables, see also
[`vignette("tech-dm-filter")`](https://dm.cynkra.com/articles/tech-dm-filter.md).

- [`dm_filter()`](https://dm.cynkra.com/reference/dm_filter.md) :
  Filtering

## Zoom

Focus on a single table, see also
[`vignette("tech-dm-zoom")`](https://dm.cynkra.com/articles/tech-dm-zoom.md).

- [`dm_zoom_to()`](https://dm.cynkra.com/reference/dm_zoom_to.md)
  [`dm_insert_zoomed()`](https://dm.cynkra.com/reference/dm_zoom_to.md)
  [`dm_update_zoomed()`](https://dm.cynkra.com/reference/dm_zoom_to.md)
  [`dm_discard_zoomed()`](https://dm.cynkra.com/reference/dm_zoom_to.md)
  : Mark table for manipulation

- [`left_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`left_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`inner_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`inner_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`full_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`full_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`right_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`right_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`semi_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`semi_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`anti_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`anti_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`nest_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`cross_join(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  [`cross_join(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_join.md)
  :

  dplyr join methods for zoomed dm objects

- [`filter(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`filter(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`filter_out(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`filter_out(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`mutate(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`mutate(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`transmute(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`transmute(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`select(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`select(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`relocate(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`relocate(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`rename(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`rename(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`distinct(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`distinct(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`arrange(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`arrange(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`slice(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`slice(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`group_by(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`group_by(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`ungroup(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`ungroup(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`summarise(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`summarise(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`reframe(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`reframe(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`count(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`count(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`tally(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`tally(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`pull(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  [`compute(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/dplyr_table_manipulation.md)
  :

  dplyr table manipulation methods for zoomed dm objects

- [`glimpse(`*`<dm>`*`)`](https://dm.cynkra.com/reference/glimpse.dm.md)
  [`glimpse(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/glimpse.dm.md)
  :

  Get a glimpse of your `dm` object

- [`unite(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/tidyr_table_manipulation.md)
  [`unite(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/tidyr_table_manipulation.md)
  [`separate(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/tidyr_table_manipulation.md)
  [`separate(`*`<dm_keyed_tbl>`*`)`](https://dm.cynkra.com/reference/tidyr_table_manipulation.md)
  :

  tidyr table manipulation methods for zoomed dm objects

- [`head(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/utils_table_manipulation.md)
  [`tail(`*`<dm_zoomed>`*`)`](https://dm.cynkra.com/reference/utils_table_manipulation.md)
  :

  utils table manipulation methods for `dm_zoomed` objects

## Wrap

Turn a `dm` object into a single table and back.

- [`dm_wrap_tbl()`](https://dm.cynkra.com/reference/dm_wrap_tbl.md)
  **\[experimental\]** : Wrap dm into a single tibble dm
- [`dm_unwrap_tbl()`](https://dm.cynkra.com/reference/dm_unwrap_tbl.md)
  **\[experimental\]** : Unwrap a single table dm
- [`dm_nest_tbl()`](https://dm.cynkra.com/reference/dm_nest_tbl.md)
  **\[experimental\]** : Nest a table inside its dm
- [`dm_pack_tbl()`](https://dm.cynkra.com/reference/dm_pack_tbl.md)
  **\[experimental\]** : dm_pack_tbl()
- [`dm_unnest_tbl()`](https://dm.cynkra.com/reference/dm_unnest_tbl.md)
  **\[experimental\]** : Unnest columns from a wrapped table
- [`dm_unpack_tbl()`](https://dm.cynkra.com/reference/dm_unpack_tbl.md)
  **\[experimental\]** : Unpack columns from a wrapped table

## Nested and packed data

New verbs that power wrapping.

- [`pack_join()`](https://dm.cynkra.com/reference/pack_join.md)
  **\[experimental\]** : Pack Join
- [`json_nest()`](https://dm.cynkra.com/reference/json_nest.md)
  **\[experimental\]** : JSON nest
- [`json_nest_join()`](https://dm.cynkra.com/reference/json_nest_join.md)
  **\[experimental\]** : JSON nest join
- [`json_pack()`](https://dm.cynkra.com/reference/json_pack.md)
  **\[experimental\]** : JSON pack
- [`json_pack_join()`](https://dm.cynkra.com/reference/json_pack_join.md)
  **\[experimental\]** : JSON pack join
- [`json_unnest()`](https://dm.cynkra.com/reference/json_unnest.md) :
  Unnest a JSON column
- [`json_unpack()`](https://dm.cynkra.com/reference/json_unpack.md) :
  Unpack a JSON column

## Materialize and upload

Get data from and to the database, see also
[`vignette("howto-dm-copy")`](https://dm.cynkra.com/articles/howto-dm-copy.md).

- [`compute(`*`<dm>`*`)`](https://dm.cynkra.com/reference/materialize.md)
  [`collect(`*`<dm>`*`)`](https://dm.cynkra.com/reference/materialize.md)
  : Materialize

- [`copy_dm_to()`](https://dm.cynkra.com/reference/copy_dm_to.md) : Copy
  data model to data source

- [`dm_sql()`](https://dm.cynkra.com/reference/dm_sql.md)
  [`dm_ddl_pre()`](https://dm.cynkra.com/reference/dm_sql.md)
  [`dm_dml_load()`](https://dm.cynkra.com/reference/dm_sql.md)
  [`dm_ddl_post()`](https://dm.cynkra.com/reference/dm_sql.md)
  **\[experimental\]** :

  Create *DDL* and *DML* scripts for a `dm` a and database connection

## Modify

Manipulate individual rows on the database, see also
[`vignette("howto-dm-rows")`](https://dm.cynkra.com/articles/howto-dm-rows.md).

- [`dm_rows_insert()`](https://dm.cynkra.com/reference/rows-dm.md)
  [`dm_rows_append()`](https://dm.cynkra.com/reference/rows-dm.md)
  [`dm_rows_update()`](https://dm.cynkra.com/reference/rows-dm.md)
  [`dm_rows_patch()`](https://dm.cynkra.com/reference/rows-dm.md)
  [`dm_rows_upsert()`](https://dm.cynkra.com/reference/rows-dm.md)
  [`dm_rows_delete()`](https://dm.cynkra.com/reference/rows-dm.md)
  **\[experimental\]** : Modifying rows for multiple tables

## Keys and cardinalities

Check fulfillment and nature of relationships between tables.

- [`dm_examine_constraints()`](https://dm.cynkra.com/reference/dm_examine_constraints.md)
  : Validate your data model
- [`enum_pk_candidates()`](https://dm.cynkra.com/reference/dm_enum_pk_candidates.md)
  [`dm_enum_pk_candidates()`](https://dm.cynkra.com/reference/dm_enum_pk_candidates.md)
  **\[experimental\]** : Primary key candidate
- [`dm_enum_fk_candidates()`](https://dm.cynkra.com/reference/dm_enum_fk_candidates.md)
  [`enum_fk_candidates()`](https://dm.cynkra.com/reference/dm_enum_fk_candidates.md)
  **\[experimental\]** : Foreign key candidates
- [`dm_examine_cardinalities()`](https://dm.cynkra.com/reference/dm_examine_cardinalities.md)
  **\[experimental\]** : Learn about your data model
- [`check_cardinality_0_n()`](https://dm.cynkra.com/reference/examine_cardinality.md)
  [`check_cardinality_1_n()`](https://dm.cynkra.com/reference/examine_cardinality.md)
  [`check_cardinality_1_1()`](https://dm.cynkra.com/reference/examine_cardinality.md)
  [`check_cardinality_0_1()`](https://dm.cynkra.com/reference/examine_cardinality.md)
  [`examine_cardinality()`](https://dm.cynkra.com/reference/examine_cardinality.md)
  : Check table relations
- [`check_key()`](https://dm.cynkra.com/reference/check_key.md) : Check
  if column(s) can be used as keys
- [`check_set_equality()`](https://dm.cynkra.com/reference/check_set_equality.md)
  : Check column values for set equality
- [`check_subset()`](https://dm.cynkra.com/reference/check_subset.md) :
  Check column values for subset

## Table surgery

Normalize and denormalize tables.

- [`decompose_table()`](https://dm.cynkra.com/reference/decompose_table.md)
  **\[experimental\]** : Decompose a table into two linked tables
- [`reunite_parent_child()`](https://dm.cynkra.com/reference/reunite_parent_child.md)
  [`reunite_parent_child_from_list()`](https://dm.cynkra.com/reference/reunite_parent_child.md)
  **\[experimental\]** : Merge two tables that are linked by a foreign
  key relation

## Database schemas

New verbs that power access to database schemas.

- [`db_schema_create()`](https://dm.cynkra.com/reference/db_schema_create.md)
  **\[experimental\]** : Create a schema on a database
- [`db_schema_drop()`](https://dm.cynkra.com/reference/db_schema_drop.md)
  **\[experimental\]** : Remove a schema from a database
- [`db_schema_exists()`](https://dm.cynkra.com/reference/db_schema_exists.md)
  **\[experimental\]** : Check for existence of a schema on a database
- [`db_schema_list()`](https://dm.cynkra.com/reference/db_schema_list.md)
  **\[experimental\]** : List schemas on a database

## Example dm objects

Ready to use and play with.

- [`dm_nycflights13()`](https://dm.cynkra.com/reference/dm_nycflights13.md)
  :

  Creates a dm object for the nycflights13 data

- [`dm_financial()`](https://dm.cynkra.com/reference/dm_financial.md)
  [`dm_financial_sqlite()`](https://dm.cynkra.com/reference/dm_financial.md)
  : Creates a dm object for the Financial data

- [`dm_pixarfilms()`](https://dm.cynkra.com/reference/dm_pixarfilms.md)
  :

  Creates a dm object for the pixarfilms data

## Structure and contents

Recreate a `dm` object.

- [`dm_paste()`](https://dm.cynkra.com/reference/dm_paste.md) : Create R
  code for a dm object
- [`dm_ptype()`](https://dm.cynkra.com/reference/dm_ptype.md) :
  Prototype for a dm object

# Articles

### All vignettes

- [Relational data with dm: Cheat
  sheet](https://dm.cynkra.com/articles/cheatsheet.md):
- [Updating tables and dm
  objects](https://dm.cynkra.com/articles/wip/dm-insert.md):
- [UNKNOWN TITLE](https://dm.cynkra.com/articles/wip/dm-readme-old.md):
- [shiny with
  {dynafilter}](https://dm.cynkra.com/articles/wip/dm-shiny-dynafilter.md):
- [Tips and
  tricks](https://dm.cynkra.com/articles/wip/dm-tips-and-tricks.md):
- [Getting started with dm](https://dm.cynkra.com/articles/dm.md):
- [Copy tables to and from a
  database](https://dm.cynkra.com/articles/howto-dm-copy.md):
- [Create a dm object from a
  database](https://dm.cynkra.com/articles/howto-dm-db.md):
- [Create a dm object from data
  frames](https://dm.cynkra.com/articles/howto-dm-df.md):
- [Insert, update, or remove rows in a
  database](https://dm.cynkra.com/articles/howto-dm-rows.md):
- [Introduction to relational data
  models](https://dm.cynkra.com/articles/howto-dm-theory.md):
- [Migration guide: 'cdm' -\>
  'dm'](https://dm.cynkra.com/articles/tech-dm-cdm.md):
- [Class dm and basic
  operations](https://dm.cynkra.com/articles/tech-dm-class.md):
- [Visualizing dm
  objects](https://dm.cynkra.com/articles/tech-dm-draw.md):
- [Filtering in relational data
  models](https://dm.cynkra.com/articles/tech-dm-filter.md):
- [Joining in relational data
  models](https://dm.cynkra.com/articles/tech-dm-join.md):
- [Manipulating individual
  tables](https://dm.cynkra.com/articles/tech-dm-keyed.md):
- [Model verification - keys, constraints and
  normalization](https://dm.cynkra.com/articles/tech-dm-low-level.md):
- [Function naming
  logic](https://dm.cynkra.com/articles/tech-dm-naming.md):
- [Zooming and manipulating
  tables](https://dm.cynkra.com/articles/tech-dm-zoom.md):