# sql

*author: junjie.jiang*


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## Desription

Read data from sqlite or mysql.

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## Code Example

### Example

```python
from towhee import DataLoader, pipe, ops
p = (
    pipe.input('image_path')
    .map('image_path', 'image', ops.image_decode.cv2())
    .map('image', 'vec', ops.image_embedding.timm(model_name='resnet50'))
    .output('vec')

)

for data in DataLoader(ops.data_source.sql('sqlite:///./sqlite.db')):
    print(p(data).to_list(kv_format=True))

# batch
for data in DataLoader(ops.data_source.sql('sqlite:///./sqlite.db'), batch_size=10):
    p.batch(data)
```

**Parameters:**


***sql_url:*** *str*

the url of the sql database for cache, such as '<db_type>+<db_driver>://<username>:<password>@<host>:<port>/<database>'

sqlite: sqlite:///./sqlite.db

mysql: mysql+pymysql://root:123456@127.0.0.1:3306/mysql


***table_name:*** *str*

table name

***cols:*** *str*

The columns to be queried, default to *, indicating all columns

If you want to query specific columns, use the column names and separate them with `,`, such as 'id,image_path,label'


***where:*** *str*

Where conditional statement, for example: id > 100

***limit:*** *int*

The default value is 500. If set to None, all data will be returned.