sql.reader: Read a database described in a .sql file.

In connectedblue/ProjectTemplate2: Provides custom template and other extensions of ProjectTemplate

Description

This function will load data from a SQL database based on configuration information found in the specified .sql file. The .sql file must specify a database to be accessed. All tables from the database, one specific tables or one specific query against any set of tables may be executed to generate a data set.

Usage

sql.reader(data.file, filename, variable.name)

Arguments

data.file	The name of the data file to be read.
filename	The path to the data set to be loaded.
variable.name	The name to be assigned to in the global environment.

Details

queries can support string interpolation to execute code snippets using mustache syntax (http://mustache.github.io). This is used to create queries that depend on data from other sources. Code delimited is {{...}}

Example: query: SELECT * FROM my_table WHERE id IN ({{ids}}). Here ids is a vector previously loaded into the Global Environment through ProjectTemplate

Examples of the DCF format and settings used in a .sql file are shown below:

Example 1 type: mysql user: sample_user password: sample_password host: localhost dbname: sample_database table: sample_table

Example 2 type: mysql user: sample_user password: sample_password host: localhost port: 3306 socket: /Applications/MAMP/tmp/mysql/mysql.sock dbname: sample_database table: sample_table

Example 3 type: sqlite dbname: /path/to/sample_database table: sample_table

Example 4 type: sqlite dbname: /path/to/sample_database query: SELECT * FROM users WHERE user_active == 1

Example 5 type: sqlite dbname: /path/to/sample_database table: *

Example 6 type: postgres user: sample_user password: sample_password host: localhost dbname: sample_database table: sample_table

Example 7 type: odbc dsn: sample_dsn user: sample_user password: sample_password dbname: sample_database query: SELECT * FROM sample_table

Example 8 type: oracle user: sample_user password: sample_password dbname: sample_database table: sample_table

Example 9 type: jdbc class: oracle.jdbc.OracleDriver classpath: /path/to/ojdbc5.jar (or set in CLASSPATH) user: scott password: tiger url: jdbc:oracle:thin:@myhost:1521:orcl query: select * from emp

Example 10 type: heroku classpath: /path/to/jdbc4.jar (or set in CLASSPATH) user: scott password: tiger host: heroku.postgres.url port: 1234 dbname: herokudb query: select * from emp

Example 11 In this example RSQLite::initExtension() is automatically called on the established connection.

Liam Healy has written extension-functions.c, which is available on http://www.sqlite.org/contrib. It provides mathematical and string extension functions for SQL queries using the loadable extensions mechanism.

type: sqlite dbname: /path/to/sample_database plugin: extension query: SELECT *,STDEV(value1) FROM example_table

Value

No value is returned; this function is called for its side effects.

Examples

library('ProjectTemplate2')

## Not run: sql.reader('example.sql', 'data/example.sql', 'example')

connectedblue/ProjectTemplate2 documentation built on May 17, 2019, 2:46 p.m.