docs/tutorial/flink/pyflink-sql.zh.md

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要在 Apache Sedona 中配置 PyFlink，请先按 [PyFlink](../../setup/flink/install-python.md) 指南完成安装。
完成后，可以运行下面的代码以验证环境是否正常工作。

```python
from sedona.flink import SedonaContext
from pyflink.datastream import StreamExecutionEnvironment
from pyflink.table import EnvironmentSettings, StreamTableEnvironment

stream_env = StreamExecutionEnvironment.get_execution_environment()
flink_settings = EnvironmentSettings.in_streaming_mode()
table_env = SedonaContext.create(stream_env, flink_settings)

table_env.sql_query("SELECT ST_Point(1.0, 2.0)").execute()
```

PyFlink 不支持把 Scala 自定义类型（UDT）转换为 Python UDT。
因此，如果想在 Python 中收集结果，需要使用 `ST_AsText` 或 `ST_ASBinary` 等函数把结果转换为字符串或二进制。

```python
from shapely.wkb import loads

table_env.sql_query("SELECT ST_ASBinary(ST_Point(1.0, 2.0))").execute().collect()

[loads(bytes(el[0])) for el in result]
```

```
[<POINT (1 2)>]
```

用户自定义标量函数（UDF）也是类似的处理方式：

```python
from pyflink.table.udf import ScalarFunction, udf
from shapely.wkb import loads


class Buffer(ScalarFunction):
    def eval(self, s):
        geom = loads(s)
        return geom.buffer(1).wkb


table_env.create_temporary_function(
    "ST_BufferPython", udf(Buffer(), result_type="Binary")
)

buffer_table = table_env.sql_query(
    "SELECT ST_BufferPython(ST_ASBinary(ST_Point(1.0, 2.0))) AS buffer"
)
```

更多 SQL 示例请参阅 FlinkSQL 章节：[FlinkSQL](sql.md)。