{"id":6693,"date":"2022-03-10T07:41:00","date_gmt":"2022-03-10T06:41:00","guid":{"rendered":"https:\/\/expert-only.com\/?p=6693"},"modified":"2023-03-23T13:32:18","modified_gmt":"2023-03-23T12:32:18","slug":"exemples-jointure-left-join-sql-server","status":"publish","type":"post","link":"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/","title":{"rendered":"Exemples de jointure LEFT JOIN avec SQL Server"},"content":{"rendered":"\n<p class=\"has-text-align-center\"><strong><em>Comment \u00e9crire une requ\u00eate de jointure Left Join avec SQL Server ?<\/em><\/strong><\/p>\n\n\n\n<p>Ces exemples de jointure LEFT JOIN \u00e9crites avec SQL Server permettent d&rsquo;extraire des donn\u00e9es de deux ou plusieurs tables en se basant sur les relations entre les objets. Les jointures LEFT JOIN SQL Server indiquent comment le moteur SQL doit utiliser les donn\u00e9es d&rsquo;une table pour s\u00e9lectionner les lignes d&rsquo;une autre table.<\/p>\n\n\n\n<p>Une jointure peut regrouper les donn\u00e9es de plusieurs tables, et chaque relation entre deux tables est indiqu\u00e9e dans la requ\u00eate. Les conditions de la requ\u00eate indiquent comment relier logiquement les donn\u00e9es entre les tables. Ainsi, les conditions de jointure peuvent \u00eatre sp\u00e9cifi\u00e9es dans la clause FROM ou la clause WHERE. Avec la clause FROM, par exemple, c&rsquo;est la relation qui filtre les donn\u00e9es affich\u00e9es.<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#1-objectif-des-jointures-sql-server\" >1. Objectif des jointures SQL Server<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#2-specificites-dune-requete-left-join-en-sql\" >2. Sp\u00e9cificit\u00e9s d&rsquo;une requ\u00eate LEFT JOIN en SQL<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#3-utilisation-de-cles-primaires-et-etrangeres\" >3. Utilisation de cl\u00e9s primaires et \u00e9trang\u00e8res<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#4-contraintes-logiques-et-physiques\" >4. Contraintes logiques et physiques<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#5-les-differents-types-de-jointures-t-sql\" >5. Les diff\u00e9rents types de jointures T-SQL<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#6-analyse-des-clefs-etrangeres-entre-les-tables\" >6. Analyse des clefs \u00e9trang\u00e8res entre les tables<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#7-exemple-de-requete-left-join-avec-sql-server\" >7. Exemple de requ\u00eate LEFT JOIN avec SQL Server<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#8-exemple-de-requete-ms-sql-left-outer-join\" >8. Exemple de requ\u00eate MS SQL LEFT OUTER JOIN<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#9-optimiser-les-performances-des-jointures-gauches-avec-sql-server\" >9. Optimiser les performances des jointures gauches avec SQL Server<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#10-conclusion-sur-les-requetes-left-join-sql-server\" >10. Conclusion sur les requ\u00eates LEFT JOIN SQL Server<\/a><\/li><\/ul><\/nav><\/div>\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1-objectif-des-jointures-sql-server\"><\/span>1. Objectif des jointures SQL Server<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>L&rsquo;objectif principal de l&rsquo;utilisation des jointures est d&rsquo;\u00e9viter de stocker les m\u00eames donn\u00e9es plusieurs fois dans une base de donn\u00e9es. C&rsquo;est ce que l&rsquo;on appelle la normalisation d&rsquo;une <a href=\"https:\/\/expert-only.com\/concepts\/systeme-de-gestion-de-base-de-donnees-ou-sgbd\/\">base de donn\u00e9es relationnelle<\/a>. <\/p>\n\n\n\n<p>Par exemple, 2 millions de lignes de vente par an mais seulement 10 magasins physiques diff\u00e9rents et 20 000 clients dans la base de donn\u00e9es. Il est pr\u00e9f\u00e9rable de stocker toutes les informations dans les tables magasins et clients une seule fois et dans une table d\u00e9di\u00e9e. Cela permet de <a href=\"https:\/\/expert-only.com\/base-sql-server\/vider-le-journal-des-transactions-sql-server\/\">r\u00e9duire la taille de la base de donn\u00e9es<\/a>. Et donc d&rsquo;am\u00e9liorer les performances.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2-specificites-dune-requete-left-join-en-sql\"><\/span>2. Sp\u00e9cificit\u00e9s d&rsquo;une requ\u00eate LEFT JOIN en SQL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>G\u00e9n\u00e9ralement, une requ\u00eate de jointure LEFT JOIN est filtr\u00e9e \u00e0 l&rsquo;aide d&rsquo;une <a href=\"https:\/\/expert-only.com\/fr\/t-sql\/creer-table-sql-server-cle-primaire\/\">cl\u00e9 primaire<\/a> dans la premi\u00e8re table (ou table principale) et d&rsquo;une cl\u00e9 \u00e9trang\u00e8re dans les autres tables. Cela permet d&rsquo;assurer la coh\u00e9rence des donn\u00e9es dans la base. Ce sont les cl\u00e9s logiques qui sont utilis\u00e9es, et il n&rsquo;est pas obligatoire que des contraintes physiques soient pr\u00e9sentes dans le mod\u00e8le de donn\u00e9es.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"3-utilisation-de-cles-primaires-et-etrangeres\"><\/span>3. Utilisation de cl\u00e9s primaires et \u00e9trang\u00e8res<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>L&rsquo;utilisation de cl\u00e9s primaires et \u00e9trang\u00e8res dans une requ\u00eate LEFT JOIN permet de relier les tables de mani\u00e8re logique et efficace. La cl\u00e9 primaire est un identifiant unique pour chaque enregistrement dans une table, tandis que la cl\u00e9 \u00e9trang\u00e8re fait r\u00e9f\u00e9rence \u00e0 la cl\u00e9 primaire d&rsquo;une autre table. Cette relation entre les cl\u00e9s permet de s&rsquo;assurer que les donn\u00e9es sont coh\u00e9rentes et fiables.<\/p>\n\n\n\n<p>Les cl\u00e9s primaires et \u00e9trang\u00e8res sont cruciales pour maintenir l&rsquo;int\u00e9grit\u00e9 r\u00e9f\u00e9rentielle dans une base de donn\u00e9es relationnelle. L&rsquo;int\u00e9grit\u00e9 r\u00e9f\u00e9rentielle garantit que les relations entre les tables sont maintenues de mani\u00e8re coh\u00e9rente et qu&rsquo;aucune donn\u00e9e orpheline (c&rsquo;est-\u00e0-dire sans r\u00e9f\u00e9rence parente) n&rsquo;est pr\u00e9sente.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"4-contraintes-logiques-et-physiques\"><\/span>4. Contraintes logiques et physiques<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Les <a href=\"https:\/\/docs.aws.amazon.com\/fr_fr\/redshift\/latest\/dg\/t_Defining_constraints.html\" target=\"_blank\" rel=\"noreferrer noopener\">contraintes<\/a> logiques sont des r\u00e8gles d\u00e9finies pour les relations entre les tables, comme les cl\u00e9s primaires et \u00e9trang\u00e8res. Les contraintes physiques, en revanche, sont des limitations impos\u00e9es par le syst\u00e8me de gestion de base de donn\u00e9es (SGBD) pour assurer l&rsquo;int\u00e9grit\u00e9 et la performance des donn\u00e9es.<\/p>\n\n\n\n<p>Dans une requ\u00eate LEFT JOIN, il n&rsquo;est pas obligatoire d&rsquo;avoir des contraintes physiques pr\u00e9sentes dans le mod\u00e8le de donn\u00e9es. Cependant, il est toujours recommand\u00e9 d&rsquo;utiliser des contraintes logiques pour assurer la coh\u00e9rence des donn\u00e9es et faciliter la compr\u00e9hension du mod\u00e8le de donn\u00e9es.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"5-les-differents-types-de-jointures-t-sql\"><\/span>5. Les diff\u00e9rents types de jointures T-SQL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Quels sont les diff\u00e9rents types de jointures T-SQL disponibles avec SQL Server ? Les diff\u00e9rents types de jointures en T-SQL sont les suivants :<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Jointure gauche &#8211; LEFT JOIN<\/strong><\/li>\n\n\n\n<li><strong>Jointure externe gauche &#8211; LEFT OUTER JOIN<\/strong><\/li>\n\n\n\n<li>Jointure droite &#8211; RIGHT JOIN<\/li>\n\n\n\n<li>Jointure externe droite &#8211; RIGHT OUTER JOIN<\/li>\n\n\n\n<li>Jointure compl\u00e8te &#8211; FULL JOIN<\/li>\n\n\n\n<li>Jointure ext\u00e9rieure compl\u00e8te &#8211; FULL OUTER JOIN<\/li>\n\n\n\n<li>Jointure interne &#8211; INNER JOIN<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Nous nous concentrerons ici sur les jointures gauches appel\u00e9es LEFT JOIN.<\/strong><\/h4>\n\n\n\n<p>Pour commencer \u00e0 illustrer les diff\u00e9rents types de jointures avec des exemples de requ\u00eates, nous avons besoin d&rsquo;un \u00e9chantillon de donn\u00e9es. Utilisons la base de donn\u00e9es Adventure Works, comme j&rsquo;utilise la version MS SQL 2019, j&rsquo;ai t\u00e9l\u00e9charg\u00e9 la base de donn\u00e9es <a href=\"https:\/\/docs.microsoft.com\/en-us\/sql\/samples\/adventureworks-install-configure?view=sql-server-ver15&amp;tabs=ssms\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">AdventureWorks2019<\/a>.<\/p>\n\n\n\n<p>Toutes les \u00e9tapes sont expliqu\u00e9es sur le site avec les liens vers toutes les versions d&rsquo;AdventureWorks, de SQL Server 2008 R2 \u00e0 SQL Server 2019. Consid\u00e9rons donc les tables Salesperson (vendeurs) et la table Store (magasins).<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"mssql\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">-- La table des vendeurs\nSELECT TOP 15\n   [BusinessEntityID], \n   [TerritoryID], \n   [SalesQuota], \n   [Bonus], \n   [CommissionPct], \n   [SalesYTD], \n   [SalesLastYear], \n   [rowguid], \n   [ModifiedDate]\nFROM [Sales].[SalesPerson];\n\n-- La table des magasins\nSELECT TOP 15\n   [BusinessEntityID], \n   [Name], \n   [SalesPersonID], \n   [rowguid], \n   [ModifiedDate]\nFROM [Sales].[Store] \nORDER BY [SalesPersonID];\n<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"6-analyse-des-clefs-etrangeres-entre-les-tables\"><\/span>6. Analyse des clefs \u00e9trang\u00e8res entre les tables<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Les tables Salesperson et Store sont li\u00e9es entre elles par une contrainte physique. Noter que la colonne SalesPersonID de la colonne [Sales].[Store] est li\u00e9e \u00e0 la colonne BusinessEntityID de la table [Sales].[SalesPerson]. <\/p>\n\n\n\n<p>Cette diff\u00e9rence dans les noms des colonnes est une source de confusion. Voici un extrait de la fa\u00e7on dont les deux tables sont li\u00e9es. Le code suivant provient de l&rsquo;instruction de cr\u00e9ation de la table [Sales].[Store] qui contient les donn\u00e9es des magasins :<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"sql\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">ADD CONSTRAINT [FK_Store_SalesPerson_SalesPersonID]\n  FOREIGN KEY([SalesPersonID]) \n    REFERENCES [Sales].[SalesPerson] ([BusinessEntityID]);\n<\/pre>\n\n\n\n<p>Les tables <em>SalesPerson<\/em> et <em>SalesTerritory<\/em> sont \u00e9galement li\u00e9es. Script extrait du code [Sales].[SalesPerson] qui contient les informations des vendeurs: <\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"sql\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">ADD  CONSTRAINT [FK_SalesPerson_SalesTerritory_TerritoryID]\n  FOREIGN KEY([TerritoryID])\n    REFERENCES [Sales].[SalesTerritory] ([TerritoryID]);\n<\/pre>\n\n\n\n<p>Une autre requ\u00eate SQL complexe et tr\u00e8s pratique permet elle de <a href=\"https:\/\/expert-only.com\/transact-sql\/pivot-sql-server\/\">pivoter les lignes d&rsquo;une table SQL Server en colonnes<\/a>.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-wp-embed is-provider-tutoriels-sql-et-it wp-block-embed-tutoriels-sql-et-it\"><div class=\"wp-block-embed__wrapper\">\n<blockquote class=\"wp-embedded-content\" data-secret=\"jAQ9JwtY4x\"><a href=\"https:\/\/expert-only.com\/fr\/t-sql\/pivot-sql-server\/\">Exemple de Requ\u00eate PIVOT SQL Server<\/a><\/blockquote><iframe loading=\"lazy\" class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"\u00ab\u00a0Exemple de Requ\u00eate PIVOT SQL Server\u00a0\u00bb &#8212; Tutoriels SQL et IT\" src=\"https:\/\/expert-only.com\/fr\/t-sql\/pivot-sql-server\/embed\/#?secret=01h2TqQbN5#?secret=jAQ9JwtY4x\" data-secret=\"jAQ9JwtY4x\" width=\"500\" height=\"282\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"7-exemple-de-requete-left-join-avec-sql-server\"><\/span>7. Exemple de requ\u00eate LEFT JOIN avec SQL Server<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Par exemple, pour afficher le nom du magasin et les informations sur les ventes du vendeur, joindre la table SalesPerson et la table Store. Il est recommand\u00e9 de cr\u00e9er un alias pour les tables afin de rendre la requ\u00eate lisible.<\/p>\n\n\n\n<p>La jointure LEFT JOIN utilise la premi\u00e8re table de la clause FROM. La table des vendeurs (SalesPerson) est donc la premi\u00e8re table. Elle joint ensuite les donn\u00e9es de la table de gauche (vendeurs) aux donn\u00e9es de la table de droite (magasins). Parmi les exemples de jointure LEFT JOIN avec SQL Server, la requ\u00eate ci-dessous r\u00e9cup\u00e8re le nom du magasin depuis la table des magasins, c&rsquo;est \u00e0 dire <strong><em>Sales.Store<\/em><\/strong>.<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"sql\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">SELECT \n   person.[BusinessEntityID],\n   store.[Name] as StoreName, \n   [TerritoryID], \n   [SalesQuota], \n   [Bonus], \n   [CommissionPct], \n   [SalesYTD], \n   [SalesLastYear], \n   person.[rowguid], \n   person.[ModifiedDate]\nFROM [Sales].[SalesPerson] person\n   LEFT JOIN [Sales].[Store] store \n      on person.BusinessEntityID = store.[SalesPersonID]\nORDER BY person.[BusinessEntityID];\n<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"8-exemple-de-requete-ms-sql-left-outer-join\"><\/span>8. Exemple de requ\u00eate MS SQL LEFT OUTER JOIN<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Les requ\u00eates LEFT JOIN et LEFT OUTER JOIN sont identiques, car elles renvoient exactement le m\u00eame jeu de donn\u00e9es. Pour supprimer les donn\u00e9es disponibles uniquement dans la table de droite, utiliser la clause WHERE. Cela permet d&rsquo;exclure les valeurs NULL, comme dans l&rsquo;exemple ci-dessous. <\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"sql\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">SELECT \n   person.[BusinessEntityID],\n   store.[Name] as StoreName, \n   [TerritoryID], \n   [SalesQuota], \n   [Bonus], \n   [CommissionPct], \n   [SalesYTD], \n   [SalesLastYear], \n   person.[rowguid], \n   person.[ModifiedDate]\nFROM [Sales].[SalesPerson] person\n   LEFT JOIN [Sales].[Store] store \n      on person.BusinessEntityID = store.[SalesPersonID]\nWHERE store.[SalesPersonID] IS NOT NULL\nORDER BY person.[BusinessEntityID];\n<\/pre>\n\n\n\n<p>Il n&rsquo;y a donc pas de <strong>diff\u00e9rence entre LEFT JOIN et LEFT OUTER JOIN<\/strong> dans les jointures SQL Server. <\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-9-optimiser-les-performances-des-jointures-gauches-avec-sql-server\"><span class=\"ez-toc-section\" id=\"9-optimiser-les-performances-des-jointures-gauches-avec-sql-server\"><\/span>9. Optimiser les performances des jointures gauches avec SQL Server<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Enfin, maintenir des temps de r\u00e9ponse acceptables pour les requ\u00eates de type LEFT JOIN n\u00e9cessite de suivre certaines bonnes pratiques. En effet, suivre ces conseils peut am\u00e9liorer la performance, la lisibilit\u00e9 et la maintenabilit\u00e9 de vos requ\u00eates LEFT JOIN SQL.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Utiliser des index sur les cl\u00e9s primaires et \u00e9trang\u00e8res pour am\u00e9liorer les performances de la requ\u00eate.<\/li>\n\n\n\n<li>\u00c9viter les jointures inutiles et les colonnes non pertinentes pour r\u00e9duire la complexit\u00e9 de la requ\u00eate.<\/li>\n\n\n\n<li>Appliquer des filtres et des conditions de recherche appropri\u00e9s pour limiter le nombre de lignes trait\u00e9es par la requ\u00eate.<\/li>\n\n\n\n<li>Utiliser des alias pour les noms de table pour am\u00e9liorer la lisibilit\u00e9 de la requ\u00eate et faciliter la maintenance.<\/li>\n\n\n\n<li>Analyser et surveiller les performances de la requ\u00eate \u00e0 l&rsquo;aide des outils de profilage et d&rsquo;optimisation fournis par le SGBD.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"10-conclusion-sur-les-requetes-left-join-sql-server\"><\/span>10. Conclusion sur les requ\u00eates LEFT JOIN SQL Server<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Cet article expose quelques Exemples de jointure LEFT JOIN avec SQL Server  avec la fa\u00e7on de construire les jointures LEFT JOIN. Les exemples de requ\u00eates SQL Server LEFT JOIN permettent d&rsquo;extraire des donn\u00e9es de plusieurs tables en se basant sur les relations entre les objets. Les conditions de jointures indiquent comment le moteur SQL doit utiliser les donn\u00e9es d&rsquo;une table pour s\u00e9lectionner les lignes d&rsquo;une autre table.<\/p>\n\n\n\n<p>L&rsquo;utilisation de cl\u00e9s primaires et \u00e9trang\u00e8res dans une requ\u00eate LEFT JOIN permet de relier les tables de mani\u00e8re logique et efficace, garantissant ainsi la coh\u00e9rence et la fiabilit\u00e9 des donn\u00e9es.<\/p>\n\n\n\n<p>Les requ\u00eates SQL Server les plus courantes restent <a href=\"https:\/\/expert-only.com\/transact-sql\/requetes-select-sql-server\/\">les requ\u00eates de<\/a><a href=\"https:\/\/expert-only.com\/fr\/t-sql\/requetes-select-sql-server\/\"> <\/a><a href=\"https:\/\/expert-only.com\/transact-sql\/requetes-select-sql-server\/\">s\u00e9lection<\/a> et d&rsquo;<a href=\"https:\/\/expert-only.com\/fr\/t-sql\/requete-sql-server-insert-into-depuis-select\/\">insertion des donn\u00e9es<\/a>.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-wp-embed is-provider-tutoriels-sql-et-it wp-block-embed-tutoriels-sql-et-it\"><div class=\"wp-block-embed__wrapper\">\n<blockquote class=\"wp-embedded-content\" data-secret=\"FGfxvxcR5w\"><a href=\"https:\/\/expert-only.com\/fr\/t-sql\/requete-sql-server-insert-into-depuis-select\/\">Requ\u00eate SQL Server Insert Into depuis un Select<\/a><\/blockquote><iframe loading=\"lazy\" class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"\u00ab\u00a0Requ\u00eate SQL Server Insert Into depuis un Select\u00a0\u00bb &#8212; Tutoriels SQL et IT\" src=\"https:\/\/expert-only.com\/fr\/t-sql\/requete-sql-server-insert-into-depuis-select\/embed\/#?secret=Tu3aUuGVyr#?secret=FGfxvxcR5w\" data-secret=\"FGfxvxcR5w\" width=\"500\" height=\"282\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\n<\/div><\/figure>\n","protected":false},"excerpt":{"rendered":"<div class=\"mh-excerpt\"><p>Comment \u00e9crire une requ\u00eate de jointure Left Join avec SQL Server ? Ces exemples de jointure LEFT JOIN \u00e9crites avec SQL Server permettent d&rsquo;extraire des donn\u00e9es de deux ou plusieurs tables en se basant sur les relations entre les <a class=\"mh-excerpt-more\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\" title=\"Exemples de jointure LEFT JOIN avec SQL Server\">&#8230;<\/a><\/p>\n<\/div>","protected":false},"author":1,"featured_media":23762,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"class_list":{"0":"post-6693","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-t-sql"},"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.7 (Yoast SEO v26.2) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Exemples de jointure LEFT JOIN avec SQL Server - T-SQL<\/title>\n<meta name=\"description\" content=\"Pour \u00e9crire une requ\u00eate de jointure LEFT JOIN avec SQL Server, utiliser ces exemples de code T-SQL pour apprendre son fonctionnement.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Exemples de jointure LEFT JOIN avec SQL Server\" \/>\n<meta property=\"og:description\" content=\"Pour \u00e9crire une requ\u00eate de jointure LEFT JOIN avec SQL Server, utiliser ces exemples de code T-SQL pour apprendre son fonctionnement.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\" \/>\n<meta property=\"og:site_name\" content=\"Tutoriels SQL et IT\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/ExpertOnlyCom\/\" \/>\n<meta property=\"article:published_time\" content=\"2022-03-10T06:41:00+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-03-23T12:32:18+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/expert-only.com\/wp-content\/uploads\/2022\/03\/coffee-A8CC7F60E0F_1920x1080.jpeg\" \/>\n\t<meta property=\"og:image:width\" content=\"1920\" \/>\n\t<meta property=\"og:image:height\" content=\"1080\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Expert-Only\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@expert_only\" \/>\n<meta name=\"twitter:site\" content=\"@expert_only\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"Expert-Only\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"7 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\"},\"author\":{\"name\":\"Expert-Only\",\"@id\":\"https:\/\/expert-only.com\/fr\/#\/schema\/person\/406a9576b52944f018739a42046873ef\"},\"headline\":\"Exemples de jointure LEFT JOIN avec SQL Server\",\"datePublished\":\"2022-03-10T06:41:00+00:00\",\"dateModified\":\"2023-03-23T12:32:18+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\"},\"wordCount\":1444,\"publisher\":{\"@id\":\"https:\/\/expert-only.com\/fr\/#organization\"},\"image\":{\"@id\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/expert-only.com\/wp-content\/uploads\/2022\/03\/coffee-A8CC7F60E0F_1920x1080.jpeg\",\"articleSection\":[\"T-SQL\"],\"inLanguage\":\"fr-FR\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\",\"url\":\"https:\/\/expert-only.com\/fr\/t-sql\/exemples-jointure-left-join-sql-server\/\",\"name\":\"Exemples de jointure LEFT JOIN avec SQL Server - 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