项目过程中发现在Oracle中调用ArcSDE的st_astext函数返回ST_Geometry类型字段的WKT文本有时空间类型前缀没有返回，例如一个点的经度为113.4，纬度为30.6，调用st_astext函数正常返回就应该是“POINT(113.4 30.6)”，但有时返回的是“(113.4 30.6)”，缺少POINT前缀，以下real_st_astext函数可解决该问题。
create or replace function real_st_astext(geom1 in clob) return clob is geometry clob; tempGeom clob; geom clob; lonlatStr clob;--第一段经纬度字符串 firstStr clob;--第一个点的经纬度 lastIndex int;--第一个点最后一次出现的游标begin geom := trim(geom1); geom := replace(geom,'( ','('); geom := replace(geom,' (','('); geom := replace(geom,') ',')'); geom := replace(geom,' )',')'); geom := replace(geom,', ',','); geometry := upper(geom); if geom like '(((%' then geometry := 'MULTIPOLYGON' || geom; else if geom like '((%' then tempGeom := substr(geom, instr(geom, '((') + 2, length(geom)); lonlatStr := substr(tempGeom, 0, instr(tempGeom, ')')-1); firstStr := trim(substr(lonlatStr, 0, instr(lonlatStr, ',')-1)); lastIndex := instr(lonlatStr, firstStr, -1); if lastIndex = length(lonlatStr) - length(firstStr) + 1 then geometry := 'POLYGON '||geom; else geometry := 'MULTILINESTRING ' || geom; end if; else if geom like '(%' then if geom like '%,%' then geometry := 'LINESTRING' || geom; else geometry := 'POINT' || geom; end if; end if; end if; end if; return geometry;end;