【Django】配置MySQL时报错

官方文档片段：[https://docs.djangoproject.com/en/2.0/topics/install/#get-your-database-running](https://docs.djangoproject.com/en/2.0/topics/install/#get-your-database-running)

运行环境

+ Python3.7
+ Django2.2.6
+ Mysql5.7

1. 下载mysqlclient

```python
   pip install mysqlclient
   ```
2. 修改setting.py的配置

```python
   DATABASES = {
       'default': {
           'ENGINE': 'django.db.backends.mysql',
           'NAME': 'demo04',
           'USER': 'root',
           'PASSWORD': 'root',
           'HOST': 'localhost',
           'PORT': 3306,
       }
   }
   ```
3. 执行迁移命令吧

```python
   python manage.py makemigrations
   python manage.py migrate
   ```

# django.dgrammingError: (1146, u"Table'' doesn't exist")

参考文章：https://stackoverflow.com/questions/27583744/django-table-doesnt-exist

```python
python manage.py makemigrations
python manage.py migrate --fake

注释掉模型

python manage.py makemigrations
python manage.py migrate
```

# Django | 模型类变更后生成迁移文件，报错:You are trying to add a non-nullable field 'BookName' to BookInfo without a default....

报错:

You are trying to add a non-nullable field 'BookName' to BookInfo without a default; we can't do that (the database needs something to populate existing rows).

Please select a fix:

1. Provide a one-off default now (will be set on all existing rows)
2. Quit, and let me add a default in [models.py](http://models.py)

原因:

在模型类中添加了一个非空字段，而该模型类对应的表中，已经存在数据，而这些现存的数据并没有新增字段的值

# you are trying to add a non-nulllable field xxx to xxx without a default

> 新增字段时报错，具体的意思，就是说该字段为非空字段，在字段出添加`null=True`

# django.db.utils.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syn tax to use near 'SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED' at line 1")

> 在生成迁移文件时`python manage.py makemigrations`，报错：django.db.utils.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syn tax to use near 'SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED' at line 1")

运行环境

- CentOS：6.5
- MySQL：5.1
- Django：2.1.1
- Python：3.7

```python
DATABASES = {
    'default':
        {
            'ENGINE': 'django.db.backends.mysql',
            'NAME': 'autotest',
            'USER': 'root',
            'PASSWORD': '123456',
            'HOST': '127.0.0.1',
            'PORT': '3306',
            'OPTIONS': {'isolation_level': None} # 加这句
        }
}
```

- 如果修改完，不起作用，那就是mysql版本太低了，不支持mysql5.5版本

Last modification：August 29th, 2020 at 06:13 am

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【Django】配置MySQL时报错