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Update howto-dm-db.Rmd #1211

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Sep 20, 2022
Merged

Update howto-dm-db.Rmd #1211

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Update howto-dm-db.Rmd
andreranza Jul 7, 2022
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Set `learn_keys = FALSE`
andreranza Jul 7, 2022
f4108ef
Revert "Set `learn_keys = FALSE`"
andreranza Jul 7, 2022
40e2ca7
Add MariaDB
andreranza Jul 7, 2022
0dd4f2b
Update vignettes/howto-dm-db.Rmd
krlmlr Sep 19, 2022
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Merge branch 'main' into patch-1
krlmlr Sep 19, 2022
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6 changes: 3 additions & 3 deletions vignettes/howto-dm-db.Rmd
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Expand Up @@ -22,12 +22,12 @@ source("setup/setup.R")
To this end, a dm object can be created from any database that has a {[DBI](https://dbi.r-dbi.org/)} backend available ([see list](https://github.com/r-dbi/backends)).

When a dm object is created via a DBI connection to an RDBMS, it can import all the tables in the database, the active schema, or a limited set.
For some RDBMS, such as Postgres and SQL Server, primary and foreign keys are also imported and do not have to be manually added afterwards.
For some RDBMS, such as Postgres, SQL Server and MariaDB, primary and foreign keys are also imported and do not have to be manually added afterwards.

To demonstrate, we will connect to a `r href("relational dataset repository", "https://relational.fit.cvut.cz/")` with a database server that is publicly accessible without registration.
It hosts a `r href("financial dataset", "https://relational.fit.cvut.cz/dataset/Financial")` that contains loan data along with relevant account information and transactions.
We chose this dataset because the relationships between `loan`, `account`, and `transactions` tables are a good representation of databases that record real-world business transactions.
The repository uses a MariaDB server for which {dm} currently does not import primary or foreign keys, so we will need to add them.
Starting from version 0.3.0, {dm} does import primary and foreign keys also from MariaDB which this repository relies on. However, for demonstration purposes, we would act as if this would not be possible. So, we will add primary and foreign keys later on using the functions `dm_add_pk()` and `dm_add_fk()`.
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Below, we open a connection to the publicly accessible database server using their documented connection parameters.
Connection details vary from database to database. Before connecting to your own RDBMS, you may want to read `vignette("DBI", package = "DBI")` for further information.
Expand Down Expand Up @@ -55,7 +55,7 @@ Creating a dm object takes a single call to `dm_from_con()` with the DBI connect
``````{r}
library(dm)

my_dm <- dm_from_con(my_db)
my_dm <- dm_from_con(my_db, learn_keys = FALSE)
my_dm
``````

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