摘要： schema(模式)一个用户下一组对象的集合，一般与用户名一致。视图CREATE [OR REPLACE] [FORCE|NOFORCE] VIEW view[(alias[, alias]...)]AS subquery[WITH CHECK OPTION [CONSTRAINT constraint]][WITH READ ONLY [CONSTRAINT constraint]];create view empvu80 as select employee_id, last_name, salary from employees where department_id = 80;desc 阅读全文

摘要： 数据库对象TableViewSequenceIndexSynonym对象名称最长30个字符，不能与当前用户下其他对象重名。create table "select" as select * from emp;select * from "select";必须有创建表的权限CREATE TABLE [schema.]table (column datatype [DEFAULT expr][, ...]);conn / as sysdba;create user test identified by test default tablespace user 阅读全文

摘要： 使用INSERT语句INSERT INTO table [(column [, column...])]VALUES (value [, value...]);INSERT INTO departments(department_id, department_name, manager_id, location_id)VALUES (70, 'Public Relations', 100, 1700);字符和日期需要用单引号INSERT INTO employeesVALUES (114, 'Den', 'Raphealy', ... 阅读全文

摘要： 集合操作符UNION/UNION ALLINTERSECTMINUSUnion All不排序，不去重，其余均升序且去重。create table e1 as select * from emp where deptno in (10,20);create table e2 as select * from emp where deptno in (20,30);select * from e1 union select * from e2 order by 8select * from e1 union all select * from e2 order by 8select * from 阅读全文

摘要： 使用子查询简单子查询SELECT select_listFROM tableWHERE expr operator (SELECT select_list FROM table);子查询可以出现在select,from和where之后，都是可以的。SELECT last_name, salaryFROM employeesWHERE salary > (SELECT salary FROM employees WHERE last_name = 'Abel');SELEC... 阅读全文

摘要： 使用连接SQL 1999SELECT table1.column, table2.columnFROM table1[NATURAL JOIN table2] |[JOIN table2 USING (column_name)] |[JOIN table2 ON (table1.column_name = table2.column_name)]|[LEFT|RIGHT|FULL OUTER JOIN table2 ON (table1.column_name = table2.column_name)]|[CROSS JOIN table2];自然连接：SELECT departme... 阅读全文