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Sql
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Jointure Sql : Inner join et Left outer join |
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Un bon exemple sur les jointures vaut mieux qu’un long discours : Voici 2 tables : | Table_A | Table_B
| | CA1 | CA2 | | 1 | AA | | 1 | AB | | 2 | AC | | 3 | AD | | 5 | AF |
| | CB1 | CB2 | | 1 | BA | | 2 | BB | | 2 | BC | | 3 | BD | | 4 | BE |
| Voici le résultat de 3 requêtes sur ces 2 tables : Select * from Table_A Inner join Table_B on CA1=CB1 | CA1 | CA2 | CB1 | CB1 | | 1 | AA | 1 | BA | | 1 | AB | 1 | BA | | 2 | AC | 2 | BB | | 2 | AC | 2 | BC | | 3 | AD | 3 | BD | Select * from Table_A Left outer join Table_B on CA1=CB1 | CA1 | CA2 | CB1 | CB1 | | 1 | AA | 1 | BA | | 1 | AB | 1 | BA | | 2 | AC | 2 | BB | | 2 | AC | 2 | BC | | 3 | AD | 3 | BD | | 5 | AF | NULL | NULL | Select * from Table_A Right outer join Table_B on CA1=CB1 | CA1 | CA2 | CB1 | CB1 | | 1 | AA | 1 | BA | | 1 | AB | 1 | BA | | 2 | AC | 2 | BB | | 2 | AC | 2 | BC | | 3 | AD | 3 | BD | | NULL | NULL | 4 | BE | |
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