Django MySQL不同查询获取多个值 [英] Django MySQL distinct query for getting multiple values
问题描述
我有一个 MySQL 数据库不幸与 Django 1.4.1一起使用。
如果我正确的话,区分功能只适用于POSTGRESQL。
我必须使一个不同的查询由多个值组成,而只有不同的一个,
这一个适用于POSTGRE,但不适用于MYSQL,
我收到以下错误;
DISTINCT ON字段是不支持此数据库后端
staff = Staff.objects.order_by('person__full_name') .distinct('person__full_name')
然后我尝试了
$ $ $ $ $ $ $ $ $ $$$$$$$$$ >
但是我没有得到不同的价值观,因为我也得到了工作人员的工作类别。但是当我不包含它,我不能得到它作为数组。
任何想法?
.distinct([* fields])
只适用于PostgresSQL 。
From distinct 文档
这里有区别。对于正常的distinct()调用,数据库会在确定哪些行不同时比较每行中的每个字段。对于具有指定字段名称的distinct()调用,数据库将仅比较指定的字段名称。
如所述,记录中的所有字段都被检查。很可能在你的情况下,你得到不同字段值的记录(更可能的情况是,如果你查询多个表ManyToMany或ForeignKey关系)。
为了合并为数组可以参考以前的问题 Django查询不同价值观工作,但我无法使用查询结果
I have a MySQL database unfortunately used with Django 1.4.1. Distinct function is only working for POSTGRESQL if i get it right.
I have to make a distinct query consist of multiple values while only distinct one,
Like; This one works for POSTGRE but not with MYSQL, I get the following error;
DISTINCT ON fields is not supported by this database backend
staff = Staff.objects.order_by('person__full_name').distinct('person__full_name')
Then I tried
staff = Staff.objects.values('person__full_name','staff_job_categories').distinct().order_by('person__full_name')
But I do not get distinct values because i get also the staff job categories. But when I dont contain it I could not get it as array.
Any idea ?
.distinct([*fields])
only works in PostgresSQL.
From distinct documentation
Here's the difference. For a normal distinct() call, the database compares each field in each row when determining which rows are distinct. For a distinct() call with specified field names, the database will only compare the specified field names.
As stated all fields in a record are checked. Mostly likely in your case you are getting records with different field values (more likely a case if you are queries multiple tables ManyToMany or ForeignKey relations).
For consolidating as array you can refer your earlier question Django Query distinct values works but i cant use the query result
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