mysql - 在 MySQL 5 中查看 + 左连接返回错误 1054

Question

我在 MySQL 5.5 中写一个视图。我的代码如下：

  DROP VIEW IF EXISTS vw_lancamentos;
  CREATE VIEW vw_lancamentos AS
  SELECT
    l.id,
    l.data_hora_lancamento,
    l.valor,
    l.descricao,
    l.veiculo_id,
    l.plano_conta_id,
    pc.id,
    pc.master_id,
    pc.descricao,
    pc.tipo_movimento
  FROM
    lancamentos l, plano_de_contas pc
  LEFT JOIN
    plano_de_contas on (l.plano_conta_id = pc.id);

当我尝试编译上面的代码时，服务器返回此错误： 错误代码：1054。“on 子句”中的未知列“l.plano_conta_id”

我怎样才能让它工作？我以前使用过 Firebird，我可以看到它与 MySQL 完全不同。

Answer 1

您的JOIN语法错误，并且您有两列同名。如果您想同时返回两者l.id，pc.id那么您将需要为这两个区分它们的字段提供别名：

CREATE VIEW vw_lancamentos AS
  SELECT
    l.id as l_id,  --  add alias
    l.data_hora_lancamento,
    l.valor,
    l.descricao,
    l.veiculo_id,
    l.plano_conta_id,
    pc.id as pc_id, --  add alias
    pc.master_id,
    pc.descricao,
    pc.tipo_movimento
  FROM lancamentos l
  LEFT JOIN plano_de_contas pc
     on l.plano_conta_id = pc.id;

Answer 2

Please try this...sorry igonore my comment, I just noticed how you are doing the LEFT JOIN. The way arrange the join Syntax is wrong...

....

 FROM lancamentos l
 LEFT JOIN
 plano_de_contas pc on (l.plano_conta_id = pc.id);

EDIT AS PER OP'S COMMENT:

in your select query you are selecting thtese...both the same... so to recorrect the reasoning, you need to add alias to one.

    l.id,
    pc.id as pcid,

EDIT:

• SQLFIDDLE DEMO : it's sufficient to provide alias to one column out of the two that has the same name/duplicate name...