## SQL FOREIGN KEY 约束SQL `FOREIGN KEY` 约束用于防止破坏表之间关系的操作。`FOREIGN KEY` 是一张表中的字段(或字段集合),它引用另一张表中的主键。具有外键的表称为子表,具有主键的表称为被引用表或父表。... ### 对于 MySQL / SQL Server / Oracle / MS Access:```sqlCREATE TABLE Orders ( OrderID int NOT NULL, OrderNumber int NOT NULL, PersonID int, PRIMARY KEY (OrderID), CONSTRAINT FK...
catch (IOException e) { result = new Result(e); } Result finalResult = result; new Handler(Looper.getMainLooper()).post(() -> updateUI(finalResult)); });}... 需要定义 Entity,Dao 以及 Database 三块即可完成数据库的配置,其他的数据库实现交由框架即可。```kotlin@Entityclass Movie() : BaseObservable() { @PrimaryKey(autoGenerate = true) var id = 0 ...
可以减少 `ConcurrentModificationException` 等多线程问题的发生,同时更重要的是避免了因为 Item 篡改带来的数据一致性问题:```kotlinviewModel.uiState.collect { when (it) { Result.Success ->... () .setInputData(workDataOf("url" to "https://the-url-of-image.com")) // set network constraint .setConstraints( Constraints.Builder().setRequiredNetworkType(NetworkType.CONNECTE...
本文汇总了云数据库 veDB MySQL 版的数据库保留关键词。 参数字段 关键字描述 UserName 或 DatabaseName accessible,account,action,actual,admin,add,adddate,after,against,aggregate,algorithm,all,alter,alway... constraint,constraint_catalog,constraint_name,constraint_schema,contains,context,continue,convert,count,cpu,create,cross,cube,curdate,current,current_date,current_time,current_timestamp,current_user...
本文汇总了云数据库 MySQL 版的预留字。 说明 在高权限账号的名称中可使用 root 和 admin。 参数字段 关键字描述 UserName或DatabaseName accessible, account, action, actual, add, adddate, admin, after, a... constraint, constraint_catalog, constraint_name, constraint_schema, contains, context, continue, convert, count, cpu, create, cross, cube, curdate, current, current_date, current_time, current_time...
[CONSTRAINT constraint_name CHECK columnExpr] : add a constraint to table.columnExpr after CHECK should be a boolean expression. If constraints are checked for every row in INSERT query. Exception ... PRIMARY KEYorder_by_column,ORDER BYorder_by_column; Truncate StatementRemoves all data from a table.Syntax sql TRUNCATE TABLE [IF EXISTS] [tableIdentifier]Example sql TRUNCATE TABLE IF EXISTS exam...
You are now connected to database "dumptest" as user "lxb".dumptest= create table dumptable(id int primary key, content char(50));CREATE TABLEdumptest= insert into dumptable values(1,'aa');INSERT 0 ... 1 aa 2 bb \.---- Name: dumptable dumptable_pkey; Type: CONSTRAINT; Schema: public; Owner: lx...
constraint,create,current_catalog,current_date,current_role,current_time,current_timestamp,current_user,default,deferrable,desc,distinct,do,else,end,except,false,fetch,for,foreign,from,grant,group,h... primary,references,returning,select,session_user,some,symmetric,table,then,to,trailing,true,union,unique,user,using,variadic,when,where,window,with 说明 仅针对小写进行校验。 byte_rds_proxy 仅在创建账...
并编排执行以生成标准的JDBC结果集。直接使用HBase API、协同处理器与自定义过滤器,对于简单查询来说,其性能量级是毫秒,对于百万级别的行数来说,其性能量级是秒。 Phoenix执行方式 批处理创建user_phoenix.sql文件,包含建表信息 sql CREATE TABLE IF NOT EXISTS us_population ( state CHAR(2) NOT NULL, city VARCHAR NOT NULL, population BIGINT CONSTRAINT my_pk PRIMARY KEY (state, city)); 创建user_phoe...