MySQL LEFT JOIN 示例 [英] MySQL LEFT JOIN example

问题描述

我正在处理 PHP 文件和 MySQL.

I am working on a PHP file and MySQL.

在一个文件中，我需要从三个表中选择记录.

On a file, I need to select records from three tables.

如果使用两个表进行查询:

If a make a query with two tables:

$query_Recordset1 = "
  SELECT * FROM tbgastos
  LEFT JOIN tbconceptosgastos
    ON tbgastos.tipoGasto = tbconceptosgastos.idConceptoGasto
  LEFT JOIN tbobras
    ON tbgastos.obra = tbobras.idObra
  ORDER BY fecha DESC
"; 

它工作正常，但如果我尝试用三个表来制作它:

it works fine, but if I try to make it with three tables:

$query_Recordset1 = "
  SELECT * FROM tbgastos
  LEFT JOIN tbconceptosgastos
    ON tbgastos.tipoGasto = tbconceptosgastos.idConceptoGasto
  LEFT JOIN tbobras
    ON tbgastos.obra = tbobras.idObra
  LEFT JOIN tbproveedores
    ON tbgastos.proveedor = tbproveedores.nombreProveedor
  ORDER BY fecha DESC
";

第三个表 (tbprovedores) 记录未显示.

the third table (tbproveedores) records are not shown.

我做错了什么?

更新

tbgastos

tbprovedores

tbproveedores

推荐答案

在您的表 tbgastos 中，您有一个 int 类型(证明者)的外键.并且您希望它与表 tbprovedores 相匹配.你不想指向 tbproveedores.idProveedor 吗?

In your table tbgastos, you have a foreign key of a int type (proveedor). And you want it to match to the table tbproveedores. Don't you want to point on tbproveedores.idProveedor ?

$query_Recordset1 = "
  SELECT * FROM tbgastos
  LEFT JOIN tbconceptosgastos
   ON tbgastos.tipoGasto = tbconceptosgastos.idConceptoGasto
 LEFT JOIN tbobras
   ON tbgastos.obra = tbobras.idObra
 LEFT JOIN tbproveedores
  ON tbgastos.proveedor = tbproveedores.idProveedor
 ORDER BY fecha DESC
";

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