ST_SRID
更新時(shí)間:
獲得軌跡的空間參考標(biāo)識(shí)符(SRID)。執(zhí)行空間相關(guān)操作時(shí),將使用SRID查找空間參考系信息,確保正確執(zhí)行計(jì)算。
語法
int ST_SRID(trajectory traj);
參數(shù)
參數(shù)名稱 | 描述 |
traj | 軌跡對(duì)象。 |
描述
SRID對(duì)應(yīng)的地理坐標(biāo)系統(tǒng)和投影信息保存在系統(tǒng)表spatial_ref_sys中。
SRID默認(rèn)值為0。
示例
select ST_SRID('{"trajectory":{"version":1,"type":"STPOINT","leafcount":2,"start_time":"2007-05-27 00:00:00","end_time":"2007-05-28 08:36:47.846","spatial":"LINESTRING(13.43593 52.41721,13.43593 52.41721)","timeline":["2007-05-27 00:00:00","2007-05-28 08:36:47.846"]}}'::trajectory);
st_srid
---------
0
(1 row)
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