MySQL嵌套查询：从两个表返回单行和多行查询
我有两个表：发票和费用，具有一对多关系。 （简化）发票有：id、描述、日期作为字段，费用有：id、id_invoice、价格、数量、日期作为字段
对于发票生成，我需要发票表中的信息，例如 id=1 以及来自的所有信息费用表，其中 id_invoice=1 （因此发票中的一行和费用中的多行）
目前我有两个单独的查询，但我想知道是否可以在单个查询中执行此操作？
谢谢
I have two tables: invoice and charges, with a one-to-many relationship. (simplified) invoice has: id, description, date as fields and charges has: id, id_invoice, price, qty, date as fields
For invoice generation I need the info from the invoice table where e.g. id=1 and also all the info from the charges table where id_invoice=1 (so one row from invoice and multiple rows from charges)
At the moment I've got two separate queries but I was wondering if it was possible to do this in a single query?
Thanks
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您可以在连接
invoice.id=charges.id_invoice的两个表之间执行简单的JOIN，对于同一张发票上的每项费用，发票字段将返回相同的结果，但它允许您在单个查询中获取数据。
该查询看起来像：
You could just do a simple
JOINbetween the two tables joining oninvoice.id=charges.id_invoiceThe invoice fields would be returned identically for every charge on the same invoice but it'd allow you to fetch the data in a single query.
The query would look something like:
对于您的需求，左连接似乎更好。例如：
可以找到 SQL 连接的一个很好的说明
For your needs, a LEFT JOIN seems better. Ex:
A nice illustration of SQL joins can be found here