CREATE TABLE id_generator ( id int(10) NOT NULL, max_id bigint(20) NOT NULL COMMENT ...
SQLCREATETABLEmy_database.my_schema.my_table(idINTAUTOINCREMENT,nameSTRING,created_atTIMESTAMP_LTZDEFAULTCURRENT_TIMESTAMP,PRIMARYKEY(id)); 1. 2. 3. 4. 5. 6. 7. 修改表 添加列或更改表结构可以通过ALTER TABLE命令来完成: 复制 SQLALTERTABLEmy_database.my_schema.my_tableADDCOLUMNemailSTRING; ...
create table `unique_id_tab` ( `id` BIGINT AUTO_INCREMENT, PRIMARY KEY ( `id` ) )ENGINE=InnoDB DEFAULT CHARSET=utf8; 这样每次我们插入ID的时候 last_insert_id = INSERT INTO `unique_id_tab` values (NULL) unique_id = ms<<22 + last_insert_id%2^22 这种ID的实现完全不依赖于服务器的节...
操作：创建数据库表 CREATE TABLE `t_num` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,`num` tinyint(1) NOT NULL DEFAULT '0',PRIMARY KEY (`id`),UNIQUE KEY `num` (`num`)) ENGINE=InnoDB DEFAULT CHARSET=utf8;通过以下sql获取id REPLACE INTO t_num (num) VALUES(0);SELECT LAST_...
SQLCREATETABLEmy_database.my_schema.my_table(idINTAUTOINCREMENT,nameSTRING,created_atTIMESTAMP_LTZDEFAULTCURRENT_TIMESTAMP,PRIMARYKEY(id)); 1. 2. 3. 4. 5. 6. 7. 修改表 添加列或更改表结构可以通过ALTER TABLE命令来完成: 复制 SQLALTERTABLEmy_database.my_schema.my_tableADDCOLUMNemailSTRING; ...
CREATETABLEt_test(idBIGINT(20) UNSIGNEDNOTNULLAUTO_INCREMENTPRIMARYKEY,stubCHAR(1)NOTNULLDEFAULT'',UNIQUEKEY stub (stub))REPLACEINTOt_test (stub)VALUES('a');SELECT*FROMt_test;SELECTLAST_INSERT_ID(); 集群分布式 那数据库自增ID机制适合作分布式ID吗?答案是不太适合 ...
CREATETABLEuser(id SnowFlakePRIMARYKEY,nameVARCHAR(50)); 1. 2. 3. 4. 上述代码定义了一个user表,其中包含一个SnowFlake类型的id字段和一个name字段。SnowFlake类型的字段可以作为表的主键使用,保证每条记录的唯一性。 SnowFlake字段类型的优势 SnowFlake字段类型在MySQL数据库中有着以下优势: ...
class MyTable(Base): id: Mapped[int] = mapped_column(primary_key=True) Base.metadata.create_all(bind=...) 运行它将发出以下SQL语句: CREATE TABLE mytable ( id INTEGER NOT NULL AUTOINCREMENT, CONSTRAINT pk_mytable PRIMARY KEY (id)
Has a default value. Has any referential integrity constraints (primary key, foreign key, etc.).In addition, this command supports the following variants:CREATE OR ALTER TABLE (creates a table if it doesn’t exist, or alters it according to the table definition) CREATE TABLE … AS SELECT (...
primary key(id), key user_name_key(user_name) )engine=INNODB 随机主键表: create table user_random_key( id BIGINT(64) notnullDEFAULT0, user_id BIGINT(64) notnullDEFAULT0, user_name VARCHAR(64) notnullDEFAULT'', sexintnotnull,