Resequencing a column with identifier in Postgresql

问题

The following code works and creates a temporary table with a sequence number which is restarted for every new name:

with results as (select row_number() over (partition by name order BY name) as mytid,name from telephn_table)
select * from results order by name

My objective however is to insert the new sequence number permanently into the telephone table. How do I transfer the new sequence number from the results table to the telephone table? I have come across the following for MySql but was not able to convert it to Postgresql.

MySQL: Add sequence column based on another field

Can anyone help?

回答1:

If memory serves, row_number() returns the number within its own partition. In other words, row_number() over (partition by name order BY name) would return 1 for each row except duplicates. You likely want rank() over (order by name) instead.

After a long discussion:

update telephn_table
set sid = rows.new_sid
from (select pkey,
             row_number() over (partition BY name) as new_sid,
             name
      from telephn_table
      ) as rows
where rows.pkey = telephn_table.pkey;

回答2:

THIS WORKS! (See my OP link to a previous MySql link. In Postgresql it works without need for a temporary table)

alter table telephn_table add column tid integer default 0; UPDATE telephn_table set tid=(SELECT count(*)+1 from telephn_table t where t.sid < telephn_table.sid and telephn_table.name=t.name)

来源：https://stackoverflow.com/questions/6037045/resequencing-a-column-with-identifier-in-postgresql

标签

postgresql

sequencing