ORACLE学习-7.数据处理

Posted 2021-01-01 Piper.Xiao

数据处理是指使用sql的DDL语句，对表中的数据进行增删改查。

插入操作

INSERT INTO    table [(column [, column...])]
VALUES        (value [, value...]);

向表中插入空值

隐式方式：在列名表中省略该字段

INSERT INTO    departments (department_id, 
                          department_name    )
VALUES        (30, ‘Purchasing‘);

显示方式：在values子句中执行null值

INSERT INTO    departments
VALUES        (100, ‘Finance‘, NULL, NULL);

插入指定的值

--记录当前系统的时间和日期
INSERT INTO employees (employee_id, 
                 first_name, last_name, 
                 email, phone_number,
                 hire_date, job_id, salary, 
                 commission_pct, manager_id,
                 department_id)
VALUES           (113, 
                 ‘Louis‘, ‘Popp‘, 
                 ‘LPOPP‘, ‘515.124.4567‘, 
                 SYSDATE, ‘AC_ACCOUNT‘, 6900, 
                 NULL, 205, 100);

从其他表中拷贝

--不必书写 VALUES 子句。 
--子查询中的值列表应与 INSERT 子句中的列名对应

INSERT INTO emp2 
SELECT * 
FROM employees
WHERE department_id = 90；


INSERT INTO sales_reps(id, name, salary, commission_pct)
SELECT employee_id, last_name, salary, commission_pct
FROM   employees
WHERE  job_id LIKE ‘%REP%‘;

更新数据

UPDATE        table
SET        column = value [, column = value, ...]
[WHERE         condition];

在update中使用子查询

--更新 114号员工的工作和工资使其与205号员工   
      相同
UPDATE   employees
SET      job_id  = (SELECT  job_id 
                    FROM    employees 
                    WHERE   employee_id = 205), 
         salary  = (SELECT  salary 
                    FROM    employees 
                    WHERE   employee_id = 205) 
WHERE    employee_id    =  114;

删除语句

DELETE FROM      table
[WHERE      condition];

在delete中使用子查询

--从emp1表中删除dept1部门名称中含Public字符的部门id

DELETE FROM emp1
WHERE  department_id =
                       (SELECT department_id
                        FROM   dept1
                        WHERE  department_name LIKE ‘%Public%‘);

数据库事物