`javascript

// standard build-call
let myQuery = sql.build({
// using '$select'-Operator
$select: {
$from: 'people'
// ...
}
});

// '$select' is an Operator and so you can use this directly
let myQuery = sql.$select({
$from: 'people'
});

// instead $from is a Helper
// and this could'nt be directly called like sql.$from({...})

`


Using a Template

A Template for writing new Helpers and Operators:

Each Operator should be located in /sql/operators/.

Use the following template to create a new Operator.

`javascript
class extends SQLBuilder.[SQLOperator | SQLHelper] {
constructor(sql){
super(sql);

// definition of allowed types and it's SQL Syntax
// more details on writing your Syntax (see 'Define a new Syntax' below)
this.Types({
// simple Type-based Syntax
// where Type is String, Number, Boolean, Primitive, Object, Array, Function
[type]: { syntax: this.Syntax(...) },

// simple type-based Syntax as iterateable with defined sub/item-types
// type can be Object or Array
[type]: {
eachItemOf: {
// type can be String, Number, Boolean, Primitive, Object, Array, Function
: { syntax: this.Syntax(...) }
}
}

// type-value-based definitions:
// type can be String, Number, Boolean
[type]: {
syntax: {
// List all values that are valid to use
// with the current Helper or Operator
[: this.Syntax(...) [,: ...]]
}
}

// type-based, iterateable and value-ased restricted Syntax
// type can be Object or Array
[type]: {
eachItemOf: {
// type can be String, Number, Boolean, Primitive, Object, Array, Function
: {
syntax: {
// List all values that are valid to use
// with the current Helper or Operator
[: this.Syntax(...) [,: ...]]
}
}
}
}

});

// optional declaration of Keywords
this.Keyword('');

// optional registration of private Helpers that are used inside the
// Syntax declared above with this.Types({...})
this.registerPrivateHelper(''); // the helper must be located in "./private//.js"
// or register your private helper by your own
this.$ = new (sql);
}

// optional function callee definition if the standard
// callee - generated by Syntax - doesn't fit
callee(/args/, identifier){
// ...
return sqlResultString;
}

// optional linker-method
link(query, identifier){
// ...
}

// optional preBuild-method
preBuild(query, identifier) {
// ...
return query;
}

// optional postBuild-method
postBuild(result, type, itemType){
// ...
return result;
}
}

module.exports = {
definition: ,
description: ,
supportedBy: {
// list all SQL-dialects that support this new Helper or Operator
// SQL-dialect can be: MySQL, MariaDB, PostgreSQL, SQLite, Oracle, SQLServer
: <'' | url to official docs>
[, : <'' | url to official docs>]
},
examples: {
// write at minimum one Test "Basic Usage" for each Type of Syntax defined above
// using the same structure as used by this.Types({...}) in the class constructor.
// Additional Tests and Examples allways wellcome!

// Example of a Test-Case for the Type "Object":
Object: {
"Basic Usage": function(sql) {
return {
// if the test is restricted to special SQL dialects
[supportedBy: {
// list all dialects (MySQL, MariaDB, PostgreSQL, SQLite, Oracle, SQLServer)
// the Test is valid for
: true
},]
test: function() {
return sql.build({
$select: {
$from: 'people'
}
});
},
expectedResults: {
sql: 'SELECT * FROM people',
values: {}

// List any SQL-dialect if the Result on Test is different to the generell Result
[,: {
sql:
values: {
$1: ...
$2: ...
}
}]
}
}
}
[, "": function(sql){
// ...
}]
}
}
}
`

$3

If there is something missing you can easily extend all your required stuff.

**If you will create a new Helper or Operator I would be glad if you will
contribute and share your magic stuff.**

The only thing you have to do is browse to the right place inside the /sql/ directory
and create a new folder and file named with the Helper or Operator.

In our Example we will create the LEFT() SQL-Function.

This file will be located at /sql/helpers/functions/string/:
- create a new Folder left
- create a new File left/left.js

Here is the code you need to write for left.js using the Template:

`javascript
'use strict';

// give the new Class the name of the Helper or Operator
class left extends SQLBuilder.SQLHelper {
constructor(sql){
// always call the construtor of SQLHelper first
super(sql);

// declare the possible types that can be used
this.Types({
Number: { syntax: this.Syntax('LEFT(, )') },
Object: { syntax: this.Syntax('LEFT(<$str>, <$len>)', SQLBuilder.CALLEE) },
});

// add each Helper defined in the Syntax as private, predefined Helper
this.$str = new SQLBuilder.SQLPredefined.StringValueParam(sql);
this.$len = new SQLBuilder.SQLPredefined.NumberValueParam(sql);
}
}

// export the new $left Helper
module.exports = {
// exports the class-definition (this is used by SQLBuilder to setup the new Helper)
definition: left,

// add some description for the auto-generation of the docs README.MD
description: Specifies the \LEFT\ function.,

// define the SQL-dialects that support this new Helper
// Each dialect listed by supported by can use this Helper. If you pass a string
// that starts with 'http://' or 'https://' inside the docs it automatically creates a link
// to the official docs
supportedBy: {
MySQL: 'https://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_left',
MariaDB: 'https://mariadb.com/kb/en/library/left/',
PostgreSQL: 'https://www.postgresql.org/docs/9.1/static/functions-string.html',
// SQLite did not support the left() function at this time
// Oracle did not support the left() function at this time --> instead we can use SUBSTR( string, start_position [, length ] ) defined as new SQLHelper
SQLServer: 'https://docs.microsoft.com/en-us/sql/t-sql/functions/left-transact-sql'
},

// Always add at least "Basic Usage" as test and example for each type you
// have declared by the new class using this.Types()
examples: {
Number: {
// Basic Usage is the Name of the Test and must always declared as function(sql)
// Parameter sql will be passed as instance of the SQLBuilder
"Basic Usage": function(sql) {
// the function always returns an Object {test: function() {}, expectedResults: {} [, supportedBy: { PostgreSQL: true, MySQL: true, ... }] }
return {
// write your test and return always the result
test: function(){
return sql.$select({
firstname: { $left: 1 }
});
},
// define the expected results of the test with
// sql as String and values as Object. If there are no values expected, so define an empty Object like values: {}
expectedResults: {
sql: 'SELECT LEFT(first_name, $1) AS first_name',
values: {
$1: 1
}
}
}
}
},
Object: {
// Basic Usage is the Name of the Test and must always declared as function(sql)
// where sql is the instance of the SQLBuilder
"Basic Usage": function(sql) {
// the function always returns an Object {test: function() {}, expectedResults: {} [, supportedBy: { PostgreSQL: true, MySQL: true, ... }] }
return {
// write your test and return always the result
test: function(){
return sql.$select({
test: { $left: { $str: 'Hello World', $len: 5 } }
});
},
// define the expected results of the test with
// sql as String and values as Object. If there are no values generated, so define an empty Object values: {}
expectedResults: {
sql: 'SELECT LEFT($1, $2) AS test',
values: {
$1: 'Hello World',
$2: 5
}
}
}
},
// Optionally add some more Tests and Examples with a different name:
"Usage of LEFT as Function": function(sql) {
return {
test: function(){
return sql.$select({
// The helper can directly used as native js-function because
// we setup the Syntax for Type "Object" with SQLBuilder.CALLEE parameter as second (see above)
test: sql.left('Hello World', 5)
});
},
expectedResults: {
sql: 'SELECT LEFT($1, $2) AS test',
values:{
$1: 'Hello World',
$2: 5
}
}
}
}
}
}
}
`

$3

Every Helper or Operator will be defined by a Type, iterateable sub-Type and optionally value restrictions.
For each of this situation you have to support a valid Syntax, that will generate the
SQL-Result-String for the Helper or Operator.

Example of SUBSTR-Syntax for Type Object

`javascript
class substr extends SQLBuilder.SQLHelper {
constructor() {
...
this.Types({
Object: { syntax: this.Syntax('SUBSTR(<$str> FROM <$start>{ FOR [$len]})', SQLBuilder.CALLEE) }
}
...
}
}
`

Okay, lets explain the magic stuff we have declared above.

By defining only the Type Object you can only use the $substr Helper like first_name: { $substr: {...} }.
If you try to use it with a Number-Value like first_name: { $substr: 5 } the SQLBuilder will throw an Error like Type Number is not allowed by Syntax.

In our case we define two required Parameters (or better say Helpers). The first one is <$str> and the second one is <$start>.
The third [$len] Helper is optional. With this informations we could write the following examples:

`javascript
let myQuery = sql.$select({
test: { $substr: { $str: 'Hello World', $start: 3 } }
});

// SQL-Output
SELECT
SUBSTR($1 FROM $2) AS test
`

#### Sub-Syntaxing

In most cases of SQL there are optional parts that also include keywords. In our Example of the SUBSTR Function it's the FOR option
that specifies the length of the substring. So we need a Sub-Syntax that will only be generated when the Helper inside is supported.
The Sub-Syntax is defined by using curly braces like { FOR [$len]}.

$3

What the hell is that?

Sometimes it's quite usefull to use a Helper as native js-Function like test: sql.substr('Hello World', 3), so
you can specifiy one Syntax per Helper or Operator as callee by adding an optional parameter to the Syntax-Function SQLBuiler.CALLEE.
This option will automatically turn the Syntax into a native js-function located on the current instance of the SQLBuilder.
In our case the Syntax of the Function will be: sql.substr(, [, options]) where options is an Object that could take all
optional Helpers defined by the Syntax.

Example
`javascript
let myQuery = sql.$select({
test: sql.substr('Hello World', 3, {
$len: 5
})
});

// SQL-Output
SELECT
SUBSTR($1 FROM $2 FOR $3) AS test
`

$3

Sometimes the auto generated callee does not fit our rules, so you can easily write your own callee by adding a method named callee to the new Helper class.
In this case you could define each Function-Parameter by your own and add code to build the SQL-Result.
Just a small Example how the substr-callee can look like.

Example
`javascript
class substr extends SQLBuilder.SQLHelper {
constructor() {
...
this.Types({
Object: { syntax: this.Syntax('SUBSTR(<$str> FROM <$start>{ FOR [$len]})') } // remove this param: , SQLBuilder.CALLEE) }
}
...
}

// add our own callee method
callee(str, start, len, identifier /identifier will always be injected by SQLBuilder as last argument/) {
// the callee-method will be executed
// in the context (this) of the current SQLBuilder instance
// !!! this is NOT the context of this class-Object
// so you have access to all useful methods of the SQlBuilder like:
// - isString(), isNumber() ...
// - isMySQL(), isPostgreSQL(), ...
// - quote(), addValue(), isCurrent(), isPreviousHelper(), ...
let sqlResult = 'SUBSTR(';

// check types
if (!this.isString(str) || !this.isNumber(start) || (len && !this.isNumber(len))) {
throw new Error('Using sql.substr failed because of wrong parameter type. Syntax is: sql.substr(str, start[,len])');
}

sqlResult += this.addValue(str) + ' FROM ' + start // we dont add start as parameter and put it directly into the SQL string //this.addValue(start);
if (len) {
sqlResult += ' FOR ' + len;
}
sqlResult += ')'

return sqlResult;
}
}

...

// Using our new selfmade CALLEE
let myQuery = sql.$select({
test: sql.substr('Hello World', 3, 5)
});

// SQL-Output
SELECT
SUBSTR($1 FROM 3 FOR 5) AS test
`

$3

About 70% or 80% of all SQL comply with the ANSI SQL-Standard. So you can write code for each Helper and Operator for each SQL-dialect or
you can add your specific Helper-Syntax as dialect-specific expression.

Example

`javascript
SELECT
{ [$top]}-->(SQLServer)
{ DISTINCT[$distinct]}
{ SQL_CALC_FOUND_ROWS[$calcFoundRows]}-->(MySQL,MariaDB)

{ <$columns>}
{ [$into]}-->(MySQL,MariaDB,SQLServer)

{ FROM [$from]} { [$join]}
{ WHERE [$where]}
{ GROUP BY [$groupBy]}
{ WITH ROLLUP[$withRollup]}-->(MariaDB,MySQL)
{ HAVING [$having]}
{ ORDER BY [$orderBy]}
{ LIMIT [$limit]}-->(MariaDB,MySQL,PostgreSQL,SQLite)
{ OFFSET [$offset]}-->(MariaDB,MySQL,PostgreSQL,SQLite)
`

The Example shows the current Syntax of the SELECT Statement. Here you can see some
dialect-specific Helpers marked with -->([,,...]).

So, if you are running SQLBuilder with PostgreSQL the $info Helper for the INTO clause
is only supported by MySQL, MariaDB and SQLServer. If you write $select: { $from: 'people', $into: ... }
the SQLBuilder will throw an Error that $into Helper is not permitted by Syntax.

$3

Sometimes you need to define an Array of columns or an Object with column-identifiers and they all need to
concatenated by comma with the previouse one. To archive this you can specifiy a concatination-String or Joiner.

Let's build a part of the $columns Helper from the $select Operator.

`javascript
let myQuery = sql.$select({
$columns: {
first_name: true,
last_name: true,
...
}
})

// SQL-Output
SELECT
first_name,
last_name,
...

// This is the definition of the $columns Helper.
// Have a look at the joiner "[ , ... ]" inside the Syntax.
class columns extends SQLBuilder.SQLHelper {
constructor(sql){
super(sql);

this.Types({
Object: {
// Here we have a iterateable...
eachItemOf: {
// ...where each value should have one of the
// following types listed:
Boolean: {
syntax: {
true: this.Syntax('[ , ... ]'),
false: this.Syntax('')
}
},
Number: {
syntax: {
1: this.Syntax('[ , ... ]'),
0: this.Syntax('')
}
},
String: { syntax: this.Syntax(' AS [ , ... ]') },
Object: { syntax: this.Syntax(' AS [ , ... ]') },
Function: { syntax: this.Syntax(' AS [ , ... ]') }
}
},
Array: {
eachItemOf: {
String: { syntax: this.Syntax('[ , ... ]') },
Object: { syntax: this.Syntax(' AS [ , ... ]') }
}
},
String: { syntax: this.Syntax('') }
});
}
}

// Joiner [ , ... ] explained:
// Each joiner has this style: "[ ... ]"
// ! note of the space chars >---^---------------^
`

Every time the Syntax includes such a declaration the SQLBuilder extracts the joiner-definition and concatenates each item with this string-definition.

Another Example of a joiner-Definition you will find at /sql/helpers/locical/and/and.js which is a Helper that is used by the $where Helper.
The joiner is defined as [ AND ... ].

$3

Each Syntax can take - so called BuiltIn-Params - to interact with the JSON-Data. For this
you have to following parameter definitions you could use inside each Syntax:

- , or
- , or
-

, :

Native replacement for the Objects Key (or Index when using an Array) and replacement for the value of an Item.
`javascript
class columns extends... {
...
this.Types({
Object: {
eachItemOf: {
String: { syntax: this.Syntax(' AS ') }
}
}
});
...
}

let myQuery = sql.$select({
$columns: {
my_key: 'my_string_value'
}
})

//SQL-Output
SELECT
my_key AS my_string_value
`


, :

Safely quoted replacement for the Objects Key (or Index when using an Array - does not really make sense :-) ) and replacement for the value of an Item.
`javascript
class columns extends... {
constructor(){
...
this.Types({
Object: {
eachItemOf: {
String: { syntax: this.Syntax(' AS ') }
}
}
});
...
}
}

let myQuery = sql.$select({
$columns: {
my_key: 'my_string_value',
'my_schema.my_table.my_col': 'my_test_alias'
}
})

//SQL-Output for PostgreSQL
SELECT
"my_key" AS "my_string_value",
"my_schema"."my_table"."my_col" AS "my_test_alias"

//SQL-Output for MySQL
SELECT
my_key AS my_string_value,
my_schema.my_table.my_col AS my_test_alias

//SQL-Output for SQLServer
SELECT
[my_key] AS [my_string_value],
[my_schema].[my_table].[my_col] AS [my_test_alias]
`


,

Parameterized Key and Value replacement where the value itself is pushed to the value-stack.

`javascript
class left extends... {
constructor(){
...
this.Types({
Number: { syntax: this.Syntax(' AS ')
});
...
}
}

let myQuery = sql.$select({
$columns: {
first_name: { $left: 1 }
}
})

//SQL-Output for PostgreSQL
SELECT
LEFT("first_name", $1) AS "first_name"

//SQL-Output for MySQL
SELECT
LEFT(first_name, ?) AS first_name

//SQL-Output for SQLServer
SELECT
LEFT([first_name], @param1) AS [first_name]

`

More Examples writing new stuff

**For more informations browse through the /sql/operator or /sql/helper directories. There are a lot
of Helpers and Operators and they all give you the best examples to write your own magic stuff.**

Tests

After changing an existing Helper, Operator or maybe creating some new stuff you should run the Test.
For this use always:

`sh
npm test
`

If you like to Test only a specific language dialect or specific helper or operator you could pass arguments for that:

`sh
npm test -- [ --language|dialect ] [ --helper|operator ]

Test only the $left-helper for language-dialect MySQL

Generating docs

The documentation will automatically rebuild with every successful Test run.
Please note that a successful Test will only be archived by running a complete Tests without a specific language, helper or operator.

License

MIT License

Copyright (c) 2017-2018 planetarydev

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.