mql-mysql

Build sql dynamically

Install

npm i --save mql-mysql

This package depends on ext-mysql which is used to make requests to the database.

Why should you use a SQL builder?

Just to be clear, IMO, you should avoid that. Whenever is possible, write down your raw sqls. But, maybe you're are building a custom report or forms and lists based in custom values, flags and your SQL starts to look something similar to:

var sql = "SELECT ";
for( var i in columns )
  sql += columns[i];
// ...
if( hasJoins )
  sql += joins.join( " " );
 
if( where )
//...

You may find this useful.

Matrix Query Language

It's not exactly a language, but a matrix object. It explains how the data you want to retrieve or set should be found. It could a json file, but there is MQL class to help you do that. Let's set up an example.

const { MQL, MQLtoMySQL } = require('mql-mysql');
const MySQL = require('ext-mysql');
 
// Set your MySQL db
process.env.ENCODE = "utf8";
process.env.MYSQL_HOSTNAME = "localhost";
process.env.MYSQL_USER = "root";
process.env.MYSQL_PASSWORD = "";
process.env.MYSQL_DATABASE = "test";
MySQL.CREATE_POOL();
 
// Create a MySQL connection
const conn = new MySQL();
await conn.init();

Our first MQL

const mql = new MQL();
 
// Set a table called persons and add two columns, id and name.
mql.addTable( 'persons' );
mql.persons.addColumn( 'id' );
mql.persons.addColumn( 'name' );
 
// Now you use this mql object to select from database.
var [sql, binds] = await MQLtoMySQL.select( mql );
console.log( sql );
// SELECT persons.id id, persons.name name FROM persons persons
 
// Or you can run to database
var [rows, fields] = await MQLtoMySQL.select( mql );

MQL.addTable( key, name = key, primary = 'id' )

The key works as an alias, but if you don't provide a (table) name, it's going to be that too. Primary is the column name of the primary key of the table.

MQL.addColumn( table, key, name = key, value = null, flag = MQL.GET )

The table is the alias you gave before (you have to set the table before the column), key works as an alias for the column, name of the column same rule of setTable. Value is used for set, where, join. And flag sets what you want to do about the column. You can access the table and set a column like mmql.myTableAlias.addColumn( 'colName' ).

Examples

This mql below create a row for person table with name and age. After it gets the insert id, it will replace the person.id with the correct value and add the address.

mql = new MQL();
 
const mql = new MQL();
 
mql.addTable( 'person' );
mql.person.addColumn( 'id' );
mql.person.addColumn( 'name', 'name', "John", MQL.SET );
mql.person.addColumn( 'age', 'age', 27, MQL.SET );
 
mql.addTable( 'address' );
mql.address.addColumn( 'id' );
mql.address.addColumn( 'person_id', 'person_id', 'person.id', MQL.JOIN );
mql.address.addColumn( 'line1', 'line1', "Street Sol VI, 123", MQL.SET );
 
var [ids, results] = MQLtoMySQL.insert( mql );

Update

This example does the same as before, but updating value. Now we have to set a column with MQL.EQUAL_TO in order to create a where rule. The address will be found because of the MQL.JOIN. It updates and get the person row, look for a address that fits the MQL.JOIN if found, updates, when not, inserts a new row.

mql = new MQL();
 
const mql = new MQL();
 
mql.addTable( 'person' );
mql.person.addColumn( 'id', 'id', 15, MQL.EQUAL_TO );
mql.person.addColumn( 'name', 'name', "John", MQL.SET );
mql.person.addColumn( 'age', 'age', 27, MQL.SET );
 
mql.addTable( 'address' );
mql.address.addColumn( 'id' );
mql.address.addColumn( 'person_id', 'person_id', 'person.id', MQL.JOIN );
mql.address.addColumn( 'line1', 'line1', "Street Sol VI, 123", MQL.SET );
 
var [ids, results] = MQLtoMySQL.update( mql );

Delete

This is the same than before, I just remove the MQL.SET columns. You could keep those there, they are ignored.

mql = new MQL();
 
const mql = new MQL();
 
mql.addTable( 'person' );
mql.person.addColumn( 'id', 'id', 15, MQL.EQUAL_TO );
 
mql.addTable( 'address' );
mql.address.addColumn( 'person_id', 'person_id', 'person.id', MQL.JOIN );
 
var [ids, results] = MQLtoMySQL.update( mql );

// TODO: More examples.