GP数据库开发语句

select to_number('1234','99999')  --1234

select to_number('1234','999')  --123

查看建表语句

select show_tableinfo('dw', 'tb_cartoon_mag_info_d');

在命令窗口查看表结构

\d 

gp查看credit4表字段信息

select * from pg_attribute where attrelid = 'credit4'::regclass limit 100;

gp查看表字段描述信息  包括表字段类型，长度，描述

select n.nspname,c.relname,col.column_name, col.data_type, col.character_maximum_length, d.description 

 from pg_class c,pg_description d,pg_namespace n, information_schema.columns col

where c.oid=d.objoid

  and c.relnamespace = n.oid

  and d.objsubid = col.ordinal_position

  and c.relname = col.table_name

  and n.nspname = col.table_schema

  and c.relname = 'tdw_labelw_user_labelweb_w'

  and n.nspname='sc'

order by d.objsubid;

----获取表的comment

select n.nspname,c.relname,d.description from pg_class c,pg_description d,pg_namespace n

where c.oid=d.objoid

  and c.relnamespace = n.oid

  and d.objsubid=0

  and c.relname like 'tmk_%'

  and n.nspname='mk'

order by c.relname

----获取表的字段信息

select col.ordinal_position,col.table_schema,col.table_name,col.column_name,

col.data_type||'('||col.character_maximum_length||')', col.data_type||'('||col.numeric_precision||','||col.numeric_scale||')'

from information_schema.columns col

where col.table_schema='sc' 

  and col.table_name ='tdw_usr_order_mail_d'

order by col.ordinal_position

select * from mk.tmk_cartoon_portal_visit_dt_cp_1_prt_pd_20150515 limit 10;

GP入库添加list分区语句：

alter table dw.tdw_serv_compln_info_file_d add partition partition_date_20150401 values(20150401)  WITH (appendonly=true, compresstype=zlib, compresslevel=5);

----删除范围分区语句

ALTER TABLE mk.tmk_mail_sms_mt_h DROP PARTITION FOR (RANK(168));

--查看GP中表分区情况

select tablename, partitiontablename, partitionrank from pg_partitions

where schemaname = 'mk'

and tablename = 'tmk_mail_sms_mt_h'

and partitiontablename = 'tmk_mail_sms_mt_h_1_prt_ph_2015060100';

----添加范围分区

ALTER TABLE mk.tmk_mail_sms_mt_h ADD PARTITION ph_20150601

START (2015060100) INCLUSIVE

END (2015060123) EXCLUSIVE;

修改GP库中字段长度(也可以修改外部表的表结构)：

alter table dw.tb_det_music_serv_info_tab_d alter column author type character varying(80);

alter table dw.tb_det_music_serv_info_tab_d alter author type character varying(90);

修改字段值：（注意：外部表可以修改表结构，但是不能做update，delete操作）

update tablename set column_name = '';

----修改表的字段名称

alter table table_name rename [column] col_name to new_name;

分区名命名原则：

日的：partition_date_yyyymmdd

月的：partition_date_yyyymm

小时的：partition_date_yyyymmddhh

删除范围分区语句

ALTER TABLE mk.tmk_mail_sms_mt_h DROP PARTITION FOR (RANK(168));

select tablename, partitiontablename, partitionrank from pg_partitions

where schemaname = 'mk'

and tablename = 'tmk_mail_sms_mt_h'

and partitiontablename = 'tmk_mail_sms_mt_h_1_prt_ph_2015060100';

添加范围分区

ALTER TABLE mk.tmk_mail_sms_mt_h ADD PARTITION ph_20150601

START (2015060100) INCLUSIVE

END (2015060123) EXCLUSIVE;