Database: Query Builder

Developed with 💙 by Jean Roldan

• Introduction
• Insert
• Select
• Where
• Update
• Delete
• Join
• Filter
• Table

# Introduction

The Database Query Builder for Dart provides an easy, efficient, and fluid interface for building or running database queries. It can be used to perform most basic (Temporary) database operations and works perfectly with postgresql we hope to add support for other managers later.

This project will momentarily depend on our source postgres library to connect to this manager and execute queries, although it is true, there are multiple ORM-based libraries, but we want to do something of our own, something CRAZY!

You can perform tests using our files or use your own database, without fear of success

# Data Methods

We have several methods to bring information from our queries: get() Returns a list of type map<String,dynamic> depending on our queries getModel<T>() Returns a list of a strongly typed class to generate direct models toSql() gets the query generated by the query builder does not require a database connection, you can use this function to generate the required SQL helping you avoid SQL injections

DB.table('products').get();
DB.table('products').getModel<Product>(Product.fromJson);
DB.table('products').toSql();

Raw Expressions

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# INSERT INTO Statements

Inserts Basic

Provides an insert method that can be used to insert records using a map(key,value)

final numRowAffected = await DB.table('persons').insert({
    'firstName': 'testFirstName',
    'lastName': 'testLastName',
    'age': 30,
}).save()

Inserts Multiple

You can insert multiple records at once using the insertAll method by passing a list of map(key,value)

final sql03 = await DB.table('persons').insertAll([
  {
    'firstName': 'testFirstName1',
    'lastName': 'testLastName1',
    'age': 10,
  },
  {
    'firstName': 'testFirstName2',
    'lastName': 'testLastName2',
    'age': 20,
  },
  {
    'firstName': 'testFirstName3',
    'lastName': 'testLastName3',
    'age': 30,
  }
]).save();

Inserts Get ID

You can get the id of the affected row using insertGetId, this will perform an internal query to get the primary key

final numRowAffected = await DB.table('persons').insertGetId({
    'firstName': 'testFirstName',
    'lastName': 'testLastName',
    'age': 30,
}).save()

If you want to avoid double query or you do not have the permissions to read these attributes and improve the performance of the query, indicate what is your primary key

final numRowAffected = await DB.table('persons').insertGetId({
    'firstName': 'testFirstName',
    'lastName': 'testLastName',
    'age': 30,
},
'id').save()

In the same way you can insert multiple records and get their IDs

final numRowAffected = DB.table('people').insertAllGetIds(
  [
    {
      'first_name': 'new first name 1',
      'last_name': 'new first last name 1',
      'age': 12,
    },
    {
      'first_name': 'new first name 2',
      'last_name': 'new first last name 2',
      'age': 17,
    },
    {
      'first_name': 'new first last name 3',
      'last_name': 'new first last name 3',
      'age': 118,
    }
  ],
  'id',
);

# SELECT Statements

select

DB.table('persons').select(['firstName','age']).get();

distinct

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# WHERE Statements

Where Clauses

Make simple queries

DB.table('people').where('age', '10').get();

You can also use your own conditionals

await DB.table('people').where('age', '=', 10).get();

otherwise we offer you a strongly typed conditional

await DB.table('people').where('age', WhereType.equal, '10').get();
await DB.table('people').where('age', WhereType.greaterThan, '10').get();
await DB.table('people').where('age', WhereType.greaterThanOrEqual, '10').get();
await DB.table('people').where('age', WhereType.lessThan, '10').get();
await DB.table('people').where('age', WhereType.lessThanOrEqual, '10').get();
await DB.table('people').where('age', WhereType.like, '10').get();

Where Nested

If you already saw how the assignment of where statements works, you can do it in nested ways at your whim

DB.table('people')
  .where('age', 25)
  .where('age', '=', 10)
  .where('age', WhereType.greaterThan, 80)
  .get();

Where IN

DB.table('people').whereIN('age', [10, 20, 30])

Where OR

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Where NULL

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Where EXIST

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Where NOT EXIST

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# UPDATE SET Statements

update

DB.table('persons')
  .update({'firstName': 'new first name', 'lastName': 'new last name'})
  .save();

update with conditional

DB.table('persons')
  .update({'firstName': 'new first name', 'lastName': 'new last name'})
  .where('id', '1')
  .save();

Update or Insert

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# DELETE Statements

Delete

You can delete all records from your table

DB.table('people').delete().save()

Delete with conditional

performs a search for the record to delete

DB.table('people').delete().where('id', 5).save();

# JOIN Statements

Join

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LeftJoin

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RightJoin

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CrossJoin

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# FILTERS

OrderBy

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GroupBy

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Limit

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# AGGREGATES

Max

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Count

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Increment

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Decrement

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# TABLE

Drop table

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Truncate table

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