![]() Queries from R return a data frame, which is the standard data structure in R, allowing you to run regressions or plot the data directly. ![]() The simplest possible query is to pull all of the data from a particular table. dbWriteTable(conn=db.sales, name="salesdb1", sales1, overwrite=TRUE,ĭbWriteTable(conn=db.sales, name="salesdb2", sales2, overwrite=TRUE, ![]() Next, create the tables salesdb1 and salesdb2 inside the database, holding the data in sales1 and sales2, respectively. Once that information is processed, the variable db.sales holds the information necessary to query sales.sqlite as an SQLite database. If no database by that name exists, it will be created as needed. ![]() The second argument gives the name of the database file that is stored on your disk. The first argument, SQLite(), identifies the connection as an SQLite database rather than, say, a MariaDB database. The database connection tells R how to connect to the database to execute queries. db.sales <- dbConnect(SQLite(), dbname="sales.sqlite")ĭbConnect will create a new database connection. They are regular read.csv calls that create data frames in R. A point of confusion for some students is that they think the above code has somehow created tables in an SQLite database. You now have two data frames loaded into R. You’ll need to install it if it’s not already installed. Save both of them in the directory you’re using to run this code. Since you’d have to install and set up a database server to work with the other databases, we’ll stick to SQLite. The key difference from SQLite is that they’re not built into R. The information should apply to other SQL databases such as Microsoft’s SQL Server, MariaDB, or PostgreSQL. Most of the SQL operations we’ll discuss in this lecture are not specific in any way to SQLite. In this lecture, we’re going to go beyond the basics a little bit, and we’ll use something closer to economic data. Queries are typically done with calls to the SELECT statement. We saw how to do the basic operations to create and query data. ![]() That means every recent installation of R has an SQL database inside it.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |