postgresql数据库

Postgresql中的表名和字段名最好用小写字母，如果有大写字母，一定要用双引号。字符串值用单引号。

1、导入csv格式的数据到postgresql中：

先把数据整理成csv格式的，注意编码为UTF-8，字段之间用逗号隔开，csv文件要带字段名，或在pdadmin中点击工具栏“执行任意的SQL查询”，输入：

copy cun_name(xzqdm,xzqmc,cm,jd,wd)

from  'E:\project\jzfp\zll_cun.csv'

with(format csv,header true,quote '"',delimiter ',',encoding 'UTF-8');

2、两表通过公共字段联合更新

UPDATE public.xian

SET code = public."DMSJ"."Code"

     from public."DMSJ"

                where xian.xm = "DMSJ"."Name";

update cun set "xianId" = (select id from xian) where cun."xianName" = xian.name

3、postgresql中的geometry字段类型转化为字符串类型

SELECT ST_AsText("Center") from public."DMSJ" ;

4、将一张表的数据赋给另一张表

INSERT INTO public.dmsj(code, wz, center, name, fullname)

   select public."DMSJ"."Code", ST_AsText(public."DMSJ"."WZ"), ST_AsText(public."DMSJ"."Center"),   
   
   public."DMSJ"."Name", public."DMSJ"."FullName" from public."DMSJ";

5、查询某个字符的位置

SELECT position('.' in "fullname")

FROM public.dmsj

    where code = '310110';

6、字符串转数组

SELECT string_to_array("fullname",'.')

FROM public.dmsj

where code = '310110';

7、字段按照指定的字符进行分割，并返回指定位置的子字符结果

SELECT split_part("fullname",'.',1)

FROM public.dmsj

where code = '530629';

8、删除null值

DELETE FROM public.dmsj

WHERE "isPK" is null;

9、查询某个字段并去除重复值：

SELECT distinct sheng FROM public.dmsj;

10、通过两张表的公共字段，用一张表的字段更新另一张表的字段

update shi  set "shengId" = (select  id from sheng  where  sheng.name = shi."shengName" )

update shi  set "shengId" = (select  id from sheng  where  sheng.name = shi."shengName"  limit 1)

11、空间包含查询

select  t.*  from  "GFGX_Y_DMK_DMSJ"  t inner join "DMSJ" h

on ST_Contains(ST_GeomFromText(ST_astext(h. "WZ")),ST_GeomFromText(ST_astext(t."WZ")))   

where  h."Code" = '530621'  limit 20