https://github.com/decisionpatterns/sql.template
Light-weight, SQL Templates for R
https://github.com/decisionpatterns/sql.template
Last synced: 7 months ago
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Light-weight, SQL Templates for R
- Host: GitHub
- URL: https://github.com/decisionpatterns/sql.template
- Owner: decisionpatterns
- License: other
- Created: 2019-10-13T13:32:34.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-06-29T08:33:34.000Z (almost 5 years ago)
- Last Synced: 2024-08-13T07:11:49.567Z (10 months ago)
- Language: R
- Size: 46.9 KB
- Stars: 2
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: NEWS.md
- License: LICENSE
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README
# SQL Templar 0.1 - Language-, Server-, Agnostic Template Solutions for SQL Queries
**SQL Templar** is template standard for SQL. It uses mustache + SQL comments
to implement a lightweight and powerful template solution for SQL.
`sql.templar` provides a light weight, language-agnostic, implementation-agnostic
method for building parameterizaed queries. It allows some minimal logic.
sqltemplar is best demonstrated by some examples.
## Features
- Language agnostic (i.e. sharable by many languages)
- Backend/server agnostic.
- Light-weight
- Works for all SQL Statements: `SELECT`, `INSERT`, `DELETE`, `REPLACE`, ....
- Simple ... using it in 5min or less.
- Query reuse. Encourages query reuse and removing queries from
## How it works
SQL Templar works by de/activating individual lines from otherwise valid SQL
statements.
## Justification
There are many situations in which SQL queries vary only slightly from various
aspects of a software application. These multiple queries are supported in
various ways, one
## Example(s)
Some basic examples showing SQL Templar abilities:
### Standard SQL is unchanged
SELECT *
FROM CUSTOMER
WHERE CUSTOMER.AGE >= 21
SQL is unchanged.
### Parameter Substitition: `{{expr}}`
Values in {{expr}} are evaluated in the defined scope.
AGE=18
SELECT *
FROM CUSTOMER
WHERE CUSTOMER.AGE >={{AGE}}
The variable `AGE` is substitued. If `AGE` is undefined, an error is issued.
### Conditional Parameter Substitution: `--! :`
Apply line only when variable is evaluated in the defined scope.
AGE=18
SELECT *
FROM CUSTOMER
--! : WHERE CUSTOMER.AGE >= {{AGE}}
--! : AGE: WHERE CUSTOMER.AGE >= {{AGE}}
Special comments denoted by `--!:` are **activated** when those
variables/expressions are defined. Otherwise, the SQL passes unaltered. No
error is thrown.
### Conditional activation: `--!expr:`
Only activation the line when the `expr` is defined. The preceeding example
can also be written as this.
SELECT *
FROM CUSTOMER
--!AGE: WHERE CUSTOMER.AGE >= {{AGE}}
Conditional activation can be based on a different variable than what is used.
customer = TRUE
SELECT *
FROM CUSTOMER
--!customer: WHERE CUSTOMER.AGE >= 18
Use conditional activation with conditional
customer = TRUE
age = 18
SELECT *
FROM CUSTOMER
--!customer: WHERE CUSTOMER.AGE >= {{age}}
### JOINS Multiple Tables
SQL Templar can be used for multiple tables by using conditional logic on both
the
## Standards
* mustache parameters are respected
* `--! :` comment is uncommented if all whisker parameters are present
* `--!logic`:
## Ports
SQL Templar has been ported to the following languages
- [SQL](...)
- [R](https://cran.r-project.org/package=sql.templar)
- [Python](...)
## See Also
The *dplyr* packages provides and automated way of building SQL -- but that SQL
is generally generic and requires specific backend drivers.