S common operations

1. Create a table primary key auto-Increment

Create Table region (ID serial primary key, name character varying (128), value smallint default 8); # The region_seq_id table is automatically created. When you drop the region table, the region_seq_id table is automatically dropped.

 

2. the auto-increment field starts from 1 again.

# Delete all rows in the table and re-count the truncate region restart identity with the primary key; # or set the technical start value of select setval ('region _ seq_id ', 1, false)

3. Create a foreign key

Create Table user (ID serial primary key, reg_id integer references region (ID), name character varying (128); # Or create table user (ID serial primary key, reg_id integer, name character varying (128), forien key (reg_id) References region (ID ));

4. Table Modification

# Add the alter table region add column description text; # Remove the alter table region drop column description text; # modify the default value of the column alter table region alter column value set default 0; # Remove the default value of the column alter table region alter column value drop default; # modify the Data Type of the column alter table region alter column Value Type interger; # rename alter table region rename column value to region_time; # rename alter table region Rename to region_time;

 

S common operations