ALTER [ COLUMN ] column_name {SET| DROP } NOT NULL ALTER [ COLUMN ] column_name DROP EXPRESSION [ IF EXISTS ] ALTER [ COLUMN ] column_name ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( sequence_options ) ] ALTER [ COLUMN ] column_name {SETGENERATED { ALWAYS | BY DEFAULT...
看来你找到了一个小bug。我可以在Postgres 9.6和10中重新创建它：
How to add column if not exists on PostgreSQL WithPostgres 9.6this can be done using the optionif not exists ALTER TABLE table_name ADD COLUMN IF NOT EXISTS column_name INTEGER; https://stackoverflow.com/questions/12597465/how-to-add-column-if-not-exists-on-postgresql...
1.建表、删除表的DDL语句 CREATETABLEIFNOTEXISTS"my_table" ( id SERIALNOTNULL, namevarchar(255)NOTNULL, agevarchar(255)NOTNULL, dr int2DEFAULT0,PRIMARYKEY(id) );--删除表DROPTABLEIFEXISTS"my_table"; 2.字段的增删改 --新增字段ALTERTABLEmy_tableADDCOLUMNremarkVARCHAR(200);--删除表字段ALTERTA...
DROP TABLE IF EXISTS customers CASCADE; CREATE TABLE customers ( id SERIAL PRIMARY KEY, customer_name VARCHAR(255) NOT NULL ); 1) Adding a new column to a table First, add the phone column to the customers table using the ALTER TABLE...ADD COLUMN statement: ALTER TABLE customers ADD COLU...
drop indexifexists"t_user_pkey";alter table"t_user"add constraint"t_user_pkey"primarykey("ID"); 根据已有表结构创建表 代码语言:javascript 复制 create tableifnot exists新表(like 旧表 including indexes including comments including defaults); ...
COMMENT ON COLUMN public.t_user.update_time IS '更新时间'; -- 创建自增序列alter sequence "t_user_ID_seq" restart with 1 increment by 1; -- 创建主键序列 drop index if exists "t_user_pkey"; alter table "t_user" add constraint "t_user_pkey" primary key ("ID"); ...
postgres=# create temp sequence if not exists tmp_seq;postgres=# alter sequence tmp_seq restart with 1;postgres=# alter table test add column col1 int;ALTER TABLE postgres=# update test set col1=nextval('tmp_seq');UPDATE 10000000
postgres=# create temp sequence if not exists tmp_seq; postgres=# alter sequence tmp_seq restart with 1; postgres=# alter table test add column col1 int; ALTER TABLE postgres=# update test set col1=nextval(‘tmp_seq’); UPDATE 10000000 ...
括号内是字段的定义,column_name是字段的名称,data_type是它的类型,column_constraint是可选的字段约束;多个字段使用逗号进行分隔。 最后,table_constraint是可选的表级约束。 来看一个具体的例子: CREATETABLEdepartments(department_idINTEGERNOTNULLPRIMARYKEY,department_nameCHARACTERVARYING(30)NOTNULL); ...