postgresql 空间表转geojson格式数据，且包含属性信息

WITH feature AS (
    SELECT
        'Feature' AS "type",
        st_asgeojson ( hn.geom ) :: json AS "geometry",
            row_to_json (
            hnn) AS "properties"
    FROM
        tablename AS hn,
        (select gid, name from tablename) as hnn
        where hn.gid = hnn.gid
    ),
    features AS (
    SELECT
        'FeatureCollection' AS "type",
        array_to_json ( ARRAY_AGG ( feature.* ) ) AS "features"
    FROM
        feature) SELECT
        row_to_json ( features.* )
FROM
    features

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道可道，非常道；名可名，非常名。无名，天地之始，有名，万物之母。故常无欲，以观其妙，常有欲，以观其徼。此两者，同出而异名，同谓之玄，玄之又玄，众妙之门。