postgresql中,许多ddl语句支持if exists、if not exists。例如: postgres=# create table if not exists abce(); CREATE TABLE postgres=# drop table if exists abce; DROP
InPostgreSQL, theDROP COLUMNcommand is used to drop an individual column or multiple columns. TheDROP COLUMNstatement inPostgreSQLis used with the collaboration of theALTER TABLEcommand. InPostgreSQL,some options like“CASCADE”and“IF NOT EXISTS”can be used with theDROP COLUMNcommand to achieve di...
alter sequence"t_user_ID_seq"restartwith1increment by1;--创建主键序列 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 incl...
If you remove a column that does not exist, PostgreSQL will issue an error. To remove a column if it exists only, you can use theIF EXISTSoption as follows: ALTERTABLEtable_nameDROPCOLUMNIFEXISTScolumn_name; In this syntax, if you remove a column that does not exist, PostgreSQL will iss...
DROP DATABASE 会删除数据库的系统目录项并且删除包含数据的文件目录。 DROP DATABASE 只能由超级管理员或数据库拥有者执行。 DROP DATABASE 命令需要在 PostgreSQL 命令窗口来执行,语法格式如下: DROPDATABASE[IF EXISTS]name 参数说明: IF EXISTS:如果数据库不存在则发出提示信息,而不是错误信息。
ALTERTABLEpublic.table_nameALTERCOLUMNcol3DROPDEFAULT; 七、pg新增字段 代码语言:javascript 复制 ALTERTABLEpublic.table_nameADDcolumn col3 int; 八、pg删除字段 代码语言:javascript 复制 ALTERTABLEpublic.table_nameDROPCOLUMNifexists col3;ALTERTABLEpublic.table_nameDROPCOLUMNcol3 cascade; ...
drop database [数据库名]; *重命名一个表: alter table [表名A] rename to [表名B]; *删除一个表: drop table [表名]; *在已有的表里添加字段: alter table [表名] add column [字段名] [类型]; *删除表中的字段: alter table [表名] drop column [字段名]; ...
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"); ...
DROP INDEX IF EXISTS IDX_USER_NAME; CREATE INDEX IDX_USER_NAME ON USER (LOWER(USER_NAME)); 查询 SELECT ID,USER_NAME FROM USER WHERE LOWER(USER_NAME) = LOWER('Bean'); 3 使用存储过程来添加字段并赋值(20190422) 使用存储过来添加字段&&赋值 ...
五十八、DROP DATABASE DROP DATABASEDROP DATABASE — 移除一个数据库大纲DROP DATABASE [ IF EXISTS ] name [ [ WITH ] ( option [, ...] ) ] 其中 选项 可以是: FORCE描述DROP DATABASE移除一个数据库。它会移除该数据… 阅读全文 五十七、DROP CONVERSION ...