#leftjoin

[ibarrau]

Confusión... Join de Tablas

La explosión de SelfService Bi ha hecho que el día día de queries y cruces de datos sea cada vez menos convencional de hacer codeando. Las nuevas tecnologías que relacionan tablas y modelos tabulares puede que nos quiten ese encaje rústico de tablas. Para ello y quienes está comprendiendo como mezclar datos entre tablas es que escribo este artículo de Joins. 

Cuantas veces nos confunden los Joins en materia de cruce de datos. ¿Cual es el left join, cual es el inner, cual es full, outer, etc.? Para no perder de vista como funciona el cruce de datos les dejo este Power Bi que los ayudará a entender como funciona cada uno en materia T-SQL principalmente.

[code-tips]

DELETE Multitabla (MySQL)

DELETE JOIN

INNER JOIN

DELETE T1, T2 FROM T1 INNER JOIN T2 ON T1.key = T2.key WHERE condition;

LEFT JOIN

DELETE T1 FROM T1 LEFT JOIN T2 ON T1.key = T2.key WHERE T2.key IS NULL;

[blogmirchi200]

SQL query interview questions for both freshers and experienced.

SQL query interview questions for both freshers and experienced. Read the full article

[ilustracode-blog]

👨‍💻👩‍💻🤓 Veja os principais tipos de junções que podemos fazer entre as tabelas. Pode ser muito útil quando for trabalhar no seu projeto 😉 ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ Mais conteúdos: @ilustra.code ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ #ilustracode #ilustraCode #icdiretoaoponto #sql #mysql #bancodedados #desenvolvedor #backend #dicailustracode #desenvolvedorweb #innerjoin #leftjoin #rightjoin https://www.instagram.com/p/B0TVIceAGUs/?igshid=152e0g4xmpj4y

[chandanmistry89]

Laravel join with where condition ->leftjoin('questions_answers_i18n', function ($join) use ($language_id) { $join->on('questions_answers.id', '=', 'questions_answers_i18n.questions_answer_id') ->where('questions_answers_i18n.lang_id', $language_id); })

[thecampcodes]

Merge Two Table Using MySQLi in PHP

In this tutorial, we will create a Merge Two Table using MySQLi. This code will merge the two existing tables in the MySQLi server when the user clicks the merge button. The system uses a MySQLi SELECT() function and adds a LEFT JOIN parameter to merge the two existing tables into one that has the same key in both. This is a user-friendly kind of program feel free to the user in your application. We will be using PHP as a scripting language that manages a database server to handle a bulk of data per transaction. It describes as an advanced technology that manages both server and control-block of your machine. Getting Started: First, you have to download & install XAMPP or any local server that runs PHP scripts. Here's the link for the XAMPP server https://www.apachefriends.org/index.html. And, this is the link for the bootstrap that I used for the layout design https://getbootstrap.com/. Creating Database Open your database web server, then create a database name in it db_merge; after that, click Import, then locate the database file inside the folder of the application then click ok. Creating the database connection Open your any kind of text editor(notepad++, etc..). Then just copy/paste the code below then name it conn.php. Creating The Interface This is where we will create a simple form for our application. To create the forms simply copy and write it into your text editor, then save it as index.php. #createmultipletablesmysqlusingphp #crossjoinoracle #fullinnerjoin #fullouterjoinmysql #howcanijointwotablesinmysql #howcanijointwotablesinphp #howcanimergetwotablesindatabase #howmergeworksinmysql #howtofetchdatafromthreetablesinmysqlusingphp #howtofetchdatafromtwotablesinmysqlusingphp #howtofetchdatafromtwotablesinmysqlwithoutjoin #howtofetchdatafromtwotablesinmysqliusingphp #howtofetchdatafromtwotablesinsqlwithjoin #howtojoin4tablesinsqlquery #howtojointhreetablesinmysqlinphp #howtojointhreetablesinsqlusingjoins #howtojointwotableinphp #howtojointwotablesinmysql #howtojointwotablesinmysqlquery #howtojointwotablesinmysqlusingphpwithexample #howtojointwotablesinmysqlwithwhereclause #howtojointwotablesinphpmyadmin #howtolinktablesinmysql #howtolinktwotablesinmysql #howtomergetwotablesinsql #howtoretrievedatafrom4tablesinsql #howtoretrievedatafrommultipletablesinmysql #howtoretrievedatafrommultipletablesinsql #howtosearchdatafrommultipletableinmysql #howtosearchdatafrommultipletableinmysqlusingphp #howtoselectdatafromtwotablesinmysqlphp #innerjoin #innerjoin3tables #innerjoinmysql #join #joininphpmysql #joinonmultiplecolumnssql #jointablesfromdifferentdatabasesmysql #joiningmultipletablesusingmysql #leftinnerjoin #leftjoin #leftjoinmysql #leftjoinonmultiplecolumns #mariadbmergetwotables #mergeleftsql #mergemysql #mergetwodatabasetablesmysql #mergetwotableusingmysqlinphp #multipleleftjoinssql #mysqlcombinemultipletablesintoone #mysqlcombinetwoqueries #mysqlcombinetwotables #mysqlcomparetwotablesandmerge #mysqlcomparetwotablesfromdifferentdatabases #mysqlconcattwocolumnsfromdifferenttables #mysqlcreaterelationshipbetweentwotables #mysqlcrossjoin #mysqlfullouterjoin #mysqlgetdatafromtwotables #mysqlinnerjoin #mysqlinnerjoin3tables #mysqljoin #mysqljoin2tables #mysqljoincolumnsfrommultipletables #mysqljoinexample #mysqljoinmultipletables #mysqljoinontwocolumns #mysqljoinsyntax #mysqljointables #mysqljointwotables #mysqljointwotablesbyid #mysqljointwotableswithdifferentcolumns #mysqljointypes #mysqljoins #mysqljoinsexplained #mysqlleftjoin #mysqlleftjoinmultipletables #mysqlleftjoinnotworking #mysqlleftjoinnull #mysqlleftjoinwithcondition #mysqlleftjoinwithwhereclause #mysqlmergetablesexample #mysqlmergetablesfromdifferentdatabases #mysqlmergetableswithdifferentcolumns #mysqlmergetwotableswithdifferentcolumns #mysqlmergetwotableswithsamecolumns #mysqlouterjoin #mysqlouterjoinsyntax #mysqlqueryexamplesmultipletables #mysqlqueryfromtwotables #mysqlquerytwotables #mysqlsearchmultipletables #mysqlsearchmultipletablesinonequery #mysqlselectcolumnsfrommultipletables #mysqlselectfrommultipletables #mysqlselectfrommultipletableswithoutjoin #mysqlselectfromtwotablesatonce #mysqlselectmergetwotables #mysqlselectmultiplecolumnsfromdifferenttables #mysqltutorial #mysqlupdate #outerjoininsql #outerjoinmysql #phpmysqljoinmultipletables #phpmysqlleftjoinwhereclause #phpmysqlsearchmultipletablesusingakeyword #phpmysqlselectfrommultipletables #phpsqljoin #phpmyadminmergetwotables #querymultipletablesmysql #selectdatafrommultipletablesmysql #selectdatafrommultipletablesmysqlphp #selectfrom3tablesmysql #selectfrommultipletablessql #selectfromtwotableswithsamecolumnnamemysql #sqlcombinetwotables #sqlinnerjoin #sqljoin #sqljoin2tables #sqljoin3tables #sqljoin4tables #sqljoinmultipletables #sqljoinmultipletableswithconditions #sqljoinwhere #sqljoinwithwhereclauseexample #sqljoins #sqljoinsexplained #sqlleftjoin #sqlmergetwotableswithdifferentfields #sqlmergetwotableswithsamecolumns #sqlmultiplejoins #sqlon #sqlouterjoin #sqlqueryexamplesfrommultipletables #sqlselectfrommultipletableswithoutjoin #sqlunion #whentousecrossjoin Read the full article

[phungthaihy]

SQL Inner Joins and Outer Joins http://ehelpdesk.tk/wp-content/uploads/2020/02/logo-header.png [ad_1] This video explains how to use t... #agile #amazonfba #analysis #business #businessfundamentals #column #computerscience #computing #crossjoin #datamanipulationlanguage #database #dml #excel #field #financefundamentals #financialanalysis #financialmodeling #foreignkeyconstraint #forex #from #fulljoin #fullouterjoin #innerjoin #investing #join #leftjoin #leftouterjoin #microsoft #onetomany #outerjoin #pmbok #pmp #primarykey #programming #query #rdbms #realestateinvesting #record #referentialintegrity #relationaldatabasemanagementsystem #relationship #rightjoin #rightouterjoin #select #sql #stocktrading #structuredquerylanguage #table #tableau #where

[elvisinformatico]

Poco fa Elvis ci ha chiesto aiuto per interrogare il DB dei suoi amici marziani! Ci ha chiesto di insegnargli a fare delle join tra tabelle! Tranquillo Elvis, ecco un breve tutorial, se hai ancora dubbi, visita l’articolo sul Blog o seguici su Linkedin

[balazsmaria]

scala - slick - left join

I'm going to switch to English for the sake of this post.

While playing with Play Framework, Slick and Scala recently, I came across this problem when doing a left join: 

[error] SlickException: Read NULL value for column ORDERS.GUEST_ID (TypeMapper.scala:158) [error] models.BarTables$$anonfun$currentTableStateFull$1.apply(BarTable.scala:108)

Let's see what happens here:

   for{

        (guests,orders) <- Guests leftJoin Orders on (_.id === _.guestId)

    } yield (guests,orders).list

So this is how you do a left join with Slick. Here's the two tables used in the query:

object Orders extends Table[Order]("ORDERS") with CRUDModel[Order] with Logger{

  def id = column[Long]("ID", O.PrimaryKey, O AutoInc) // This is the primary key column

  def guestId = column[Long]("GUEST_ID")

  def created = column[DateTime]("CREATED")

  def delivered = column[Option[DateTime]]("DELIVERED")

  def paid = column[Option[DateTime]]("PAID")

  def * = id.? ~ guestId ~ created ~ delivered ~ paid <> (Order.apply _, Order.unapply _)

...

object Guests extends Table[User]("GUESTS") with CRUDModel[User]{

  def id = column[Long]("ID", O.PrimaryKey, O AutoInc) // This is the primary key column

  def name = column[String]("NAME")

  def email = column[String]("EMAIL")

  def * = id.? ~ name ~ email <> (User.apply _, User.unapply _)

...

That looks quite normal I guess.

But then the problem arises when there's no orders belonging to the guests, and so all the columns selected from the Orders table are null. And guestId cannot be null, it's not defined as an Option (obviously).

What am I doing wrong?

The problem is that the default projection * is used when yielding the result:

    yield (guests,orders).list

We have to provide a projection that doesn't use the default one. So after some googling and stackoverflowing, I came across this post, and then this one and the result looks like this:

  def maybe = id.? ~ guestId.?  ~ created.?  ~ delivered  ~ paid  <> (

      tupleToOrder _,

      (order: Option[Order]) => None

  )

  def tupleToOrder(orderTuple: (Option[Long],Option[Long],Option[DateTime],Option[DateTime],Option[DateTime])) : Option[Order]= orderTuple match {

   case (Some(id),Some(guestId),Some(created),delivered,paid) => Some(Order(Some(id),guestId,created,delivered,paid))

   case (None,_,_,_,_) => None

  }

So instead of using the values as they would be not-nulls, we provide a way to pass nulls, and then get an Option[Order] instead of an Order. We only have to match for Some(id) really, since if that's a null, all the other columns are null as well.

And so the original query looks like this:

    for{

        (guests,orders) <- guests(tableId) leftJoin Orders on (_.id === _.guestId)

    } yield (guests,orders.maybe)

So finally this mystery is resolved.

[phungthaihy]

SQL Joins Examples |¦| Joins in SQL |¦| SQL Tutorial http://ehelpdesk.tk/wp-content/uploads/2020/02/logo-header.png [ad_1] A SQL JOIN lets you retrieve dat... #agile #amazonfba #analysis #beginnersql #business #businessfundamentals #database #databases #easysqltutorial #excel #financefundamentals #financialanalysis #financialmodeling #forex #fulljoin #fullouterjoin #fullouterjoins #howtousejoinsinsql #innerjoin #innerjoins #investing #join #joins #joinsinsql #joinsinsqlexamples #learnsql #leftjoin #leftjoins #leftouterjoin #leftouterjoins #mariadb #microsoft #mysql #oracle #pmbok #pmp #postgresql #realestateinvesting #rightjoin #rightjoins #rightouterjoin #rightouterjoins #socratica #socraticacs #sql #sqlforbeginners #sqlserver #sqltutorial #sqlite #stocktrading #structuredquerylanguage #tableau