SQL基础-- 数据处理(DML、RETURNING、MERGE INTO)
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--SQL基礎--> 數據處理(DML、RETURNING、MERGE INTO)
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一、常用的DML語句及事物處理
??? 向表中插入數據(INSERT)
??? 更新表中數據(UPDATE)
??? 從表中刪除數據(DELETE)
??? 將表中數據和并(MERGE)
??? 控制事務(TRANSACTION)
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二、DML 可以在下列條件下執行:
??? 向表中插入數據
??? 修改現存數據
??? 刪除現存數據
??? 事務是由完成若干項工作的DML語句組成的。
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三、插入數據
??? INSERT 語句語法:
??? INSERT INTO table [(column [, column...])]
??? VALUES (value [, value...]);
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??? 使用這種語法一次只能向表中插入一條數據。
??? 為每一列添加一個新值。
??? 按列的默認順序列出各個列的值。
??? 在INSERT 子句中隨意列出列名和他們的值。
??? 字符和日期型數據應包含在單引號中。
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??? --查看emp表的表結構
?????? SQL> DESC emp;
?????? ?Name????????????????????????????????????????????????? Null???? Type
?????? ?----------------------------------------------------- -------- -----------------------
?????? ?EMPNO???????????????????????????????????????????????? NOT NULL NUMBER(4)
?????? ?ENAME????????????????????????????????????????????????????????? VARCHAR2(30)
?????? ?JOB??????????????????????????????????????????????????????????? VARCHAR2(9)
?????? ?MGR??????????????????????????????????????????????????????????? NUMBER(4)
?????? ?HIREDATE?????????????????????????????????????????????????????? DATE
?????? ?SALARY???????????????????????????????????????????????????????? NUMBER(8,2)
?????? ?DEPTNO???????????????????????????????????????????????????????? NUMBER(2)
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??? 1.向表中插入空值
?????? 隱式方式: 在列名表中省略該列的值。
?????????? SQL> INSERT INTO emp(empno,ename,job,salary)??? --列出部分列名
?????????? ? 2? VALUES(1234,'Frank','saleman',8000);
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?????????? 1 row created.
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?????????? SQL> SELECT? * FROM emp WHERE ename='Frank';
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????????????? ?EMPNO ENAME????????????????????????? JOB????????????? MGR HIREDATE????? SALARY???? DEPTNO
?????????? ---------- ------------------------------ --------- ---------- --------- ---------- ----------
????????????? ? 1234 Frank????????????????????????? saleman????????????????? ????????????8000
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?????? 顯示方式: 在VALUES 子句中指定空值NULL。
?????????? 注意此處省略了列列表，當列的列表被省略時，則values關鍵字中應當為所有的字段列提供列值
?????????? SQL> INSERT INTO emp VALUES(100,'Jack','manager',null,null,20000,10);
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?????????? 1 row created.
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??? 2.插入指定的值
?????? SYSDATE 記錄當前系統的日期和時間。
?????????? SQL> INSERT into EMP(empno,ename,job,hiredate,salary)
?????????? ? 2? VALUES(1235,'Tony','boy',sysdate,7000);
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?????????? 1 row created.
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?????????? SQL> ALTER SESSION SET nls_date_format= 'yyyy-mm-dd hh24:mi:ss';
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?????????? Session altered.
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?????????? SQL> SELECT * FROM emp WHERE ename = 'Tony';
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????????????? ?EMPNO ENAME?????????? JOB????????????? MGR HIREDATE??????????????? SALARY???? DEPTNO
?????????? ---------- --------------- --------- ---------- ------------------- ---------- ----------
????????????? ? 1235 Tony??????????? boy????????????????? 2010-06-28 13:48:59?????? 7000
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?????? 插入特定的日期值
?????????? SQL> INSERT INTO emp
?????????? ? 2? VALUES(1236,'Ben','IT',null,TO_DATE('JUN 28 2010','MON DD YYYY'),3000,20);
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??? 3.在列中使用單引號和雙引號
?????? --單引號的使用
?????????? SQL> INSERT INTO emp VALUES
?????????? ? 2? (1238,'Dan','Malley''K','',sysdate,2900,20);
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?????????? 1 row created.???
?????? ???
?????? --雙引號的使用?
?????????? SQL> INSERT INTO emp VALUES
?????????? ? 2? (1239,'Dane','A "Big" L','',sysdate,2900,20);
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?????????? 1 row created.
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?????????? SQL> SELECT * FROM emp WHERE ename LIKE 'Dan%';
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????????????? ?EMPNO ENAME????????????? JOB????????????? MGR HIREDATE??????????????? SALARY???? DEPTNO
?????????? ---------- ------------------ --------- ---------- ------------------- ---------- ----------
????????????? ? 1238 Dan??????????????? Malley'K???????????? 2010-06-28 14:04:35 ??????2900???????? 20
????????????? ? 1239 Dane?????????????? A "Big" L??????????? 2010-06-28 14:07:12?????? 2900???????? 20
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??? 4.從其它表中拷貝數據（利用子查詢向表中插入數據）
?????? 在INSERT 語句中加入子查詢。
?????? 不必書寫VALUES 子句。
?????? 子查詢中的值列表應與INSERT 子句中的列名對應
?????? --克隆表結構???
?????????? SQL> CREATE TABLE test AS SELECT * FROM scott.emp WHERE 0 = 1;
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?????????? Table created.
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?????? --使用select 子句插入新值
?????????? SQL> INSERT INTO test SELECT * FROM scott.emp;
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?????????? 21 rows created.
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?????? --使用select 子句插入部分列值
?????????? SQL> INSERT INTO test(empno,ename,job,salary)
?????????? ? 2? SELECT empno,ename,job,salary
?????????? ? 3? FROM scott.emp
?????????? ? 4? WHERE ename LIKE 'Dan%';
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?????????? 2 rows created.
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??? 5.利用替代變量向表中插入數據
?????????? SQL> INSERT INTO test(empno,ename,job,salary)
?????????? ? 2? VALUES(&empno,'&ename','&job',&salary);
?????????? Enter value for empno: 1240
?????????? Enter value for ename: Andy
?????????? Enter value for job: Singer
?????????? Enter value for salary: 3600
?????????? old?? 2: VALUES(&empno,'&ename','&job',&salary)
?????????? new?? 2: VALUES(1240,'Andy','Singer',3600)
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?????????? 1 row created.
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四、更新數據(UPDATE)
??? 語法：
?????? UPDATE table
?????? SET column = value [, column = value, ...]
?????? [WHERE? condition];
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??? 可以一次更新多條數據。
??? 使用WHERE 子句指定需要更新的數據，如果省略WHERE子句，則表中的所有數據都將被更新。
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??? 1.直接更新
?????? SQL> UPDATE emp SET salary = salary + 100 WHERE ename = 'SCOTT';
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?????? 1 row updated.
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??? 2.在UPDATE語句中使用子查詢
?????? SQL> UPDATE emp SET salary =?
?????? ? 2????? (SELECT salary FROM emp WHERE ename = 'SCOTT')
?????? ? 3? WHERE empno = 7839;
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?????? 1 row updated.
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??? 3.使用多列子查詢來修改記錄：
?????? SQL> UPDATE emp SET(job,salary)
?????? ? 2????? = (SELECT job,salary FROM emp WHERE ename = 'SCOTT')
?????? ? 3? WHERE ename = 'Jack';
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?????? 1 row updated.
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五、刪除數據
??? 使用DELETE 語句從表中刪除數據。
??? DELETE [FROM] table [WHERE condition];
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??? 1.使用WHERE 子句指定刪除的記錄，如果省略WHERE子句，則表中的全部數據將被刪除。
?????? SQL> DELETE FROM emp WHERE empno = 1234;
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?????? 1 row deleted.
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??? 2.在DELETE 中使用子查詢
?????? 在DELETE 中使用子查詢，使刪除基于另一個表中的數據。
?????? SQL> DELETE FROM emp
?????? ? 2? WHERE deptno =
?????? ? 3????? (SELECT deptno FROM scott.dept WHERE dname = 'ACCOUNTING');
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?????? 4 rows deleted.
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六、在DML語句中使用WITH CHECK OPTION
??? 子查詢可以用來指定DML語句的表和列
??? WITH CHECK OPTION 關鍵字可以防止更改不在子查詢中的行
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??? --deptno列不在select列表中，故不能被更新
?????? SQL> INSERT INTO???
?????? ? 2????? (SELECT empno,ename,job,mgr,salary FROM emp
?????? ? 3?????? WHERE deptno = 20 WITH CHECK OPTION)
?????? ? 4? VALUES(1250,'Smith','Clerk',7902,3000);
?????????? (SELECT empno,ename,job,mgr,salary FROM emp
????????????????????????????????????????????? *
?????? ERROR at line 2:
?????? ORA-01402: view WITH CHECK OPTION where-clause violation
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七、TRUNCATE TABLE 截斷表
??? 刪除所有數據，保留表結構
??? TRUNCATE TABLE語句不能回滾
??? ??? SQL> TURNCATE TABLE emp;
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八、使用默認值
??? 顯式默認值
??? 使用DEFAULT 關鍵字表示默認值
??? 可以使用顯示默認值，控制默認值的使用
??? 顯示默認值可以在INSERT 和UPDATE 語句中使用
?????????? SQL> CREATE TABLE tb??
?????????? ? 2? (
?????????? ? 3????? orderid INT PRIMARY KEY,
?????????? ? 4????? status VARCHAR2(20) DEFAULT 'Delivery' NOT NULL,
?????????? ? 5????? last_update DATE DEFAULT sysdate
?????????? ? 6? );
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?????????? Table created.
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?????????? --自動使用默認值
?????????? SQL> INSERT INTO tb(orderid) SELECT 10 FROM DUAL;
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?????????? 1 row created.
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?????????? --指定新值來覆蓋默認值
?????????? SQL> INSERT INTO tb SELECT 20, 'No Delivery','28-MAY-10' FROM DUAL;
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?????????? 1 row created.
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?????????? --使用default關鍵字來設置為默認值
?????????? SQL> SELECT * FROM tb;
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?????????? ?? ORDERID STATUS?????????????? LAST_UPDA
?????????? ---------- -------------------- ---------
????????????????? 10 Delivery???????????? 28-JUN-10
????????????????? 20 No Delivery????????? 28-MAY-10
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?????????? SQL> UPDATE tb SET status = DEFAULT WHERE orderid = 20;
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?????????? 1 row updated.
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?????????? SQL> SELECT * FROM tb;
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?????????? ?? ORDERID STATUS?????????????? LAST_UPDA
?????????? ---------- -------------------- ---------
????????????????? 10 Delivery???????????? 28-JUN-10
????????????????? 20 Delivery???????????? 28-MAY-10
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九、RETURNING 子句
??? 使用RETURNING子句返回聚合函數的結果集?????????????
?????? SQL> VARIABLE avg_salary NUMBER
?????? SQL> UPDATE emp SET salary = salary + 100
?????? ? 2? RETURNING AVG(salary) INTO : avg_salary;
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?????? 16 rows updated.
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?????? SQL> PRINT avg_salary;
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?????? AVG_SALARY
?????? ----------
?????? ?2554.6875
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十、MERGE INTO???
??? 將一個表中的行合并到另一個表中
??? MERGE INTO 語法：
?????? MERGE INTO table_name table_alias
?????? USING (table|view|sub_query) alias
?????? ON (join condition)
?????? WHEN MATCHED THEN
?????????? UPDATE SET
?????????? col1 = col_val1,
?????????? col2 = col2_val
?????? WHEN NOT MATCHED THEN
?????????? INSERT (column_list)
?????????? VALUES (column_values);
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??? --創建演示環境
?????? SQL> CONN hr/hr;
?????? Connected.
??? --從hr.job_history提取唯一的數據并復制到新表job_hs中
?????? SQL> CREATE TABLE job_hs AS
?????? ? 2? SELECT employee_id,start_date,end_date,job_id,department_id? FROM job_history jh
?????? ? 3? WHERE end_date =
?????? ? 4????? (SELECT MAX(end_date) FROM job_history WHERE employee_id = jh.employee_id);
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?????? Table created.
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?????? SQL> SELECT * FROM job_hs ORDER BY employee_id;
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?????? EMPLOYEE_ID START_DAT END_DATE? JOB_ID???? DEPARTMENT_ID
?????? ----------- --------- --------- ---------- -------------
????????????? 101 28-OCT-93 15-MAR-97 AC_MGR?????????????? 110
????????????? 102 13-JAN-93 24-JUL-98 IT_PROG?????????????? 60
????????????? 114 24-MAR-98 31-DEC-99 ST_CLERK????????????? 50
????????????? 122 01-JAN-99 31-DEC-99 ST_CLERK????????????? 50
????????????? 176 01-JAN-99 31-DEC-99 SA_MAN??????????????? 80
????????????? 200 01-JUL-94 31-DEC-98 AC_ACCOUNT??????????? 90
????????????? 201 17-FEB-96 19-DEC-99 MK_REP??????????????? 20
??? --將hr.employees中的記錄當job_hs中存在時，則更新相關項，否則插入到job_hs表中??????
?????? SQL> MERGE INTO job_hs h
?????? ? 2? USING employees e
?????? ? 3? ON (h.employee_id = e.employee_id)
?????? ? 4? WHEN MATCHED THEN
?????? ? 5? UPDATE
?????? ? 6????? SET
?????? ? 7???????? start_date = sysdate,
?????? ? 8???????? end_date = sysdate + 100,
?????? ? 9???????? job_id = e.job_id,
?????? ?10???????? department_id = e.department_id
?????? ?11? WHEN NOT MATCHED THEN
?????? ?12????? INSERT (h.employee_id,h.start_date,h.end_date,h.job_id,h.department_id)
?????? ?13????? VALUES (e.employee_id,e.hire_date,sysdate,e.job_id,e.department_id);
?????? ?
?????? ?SQL> SELECT COUNT(*) FROM job_hs;
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?????? ? COUNT(*)
?????? ----------
?????????? ?? 107
?????????? ??
??? MERGE INTO 使用注意事項
??? ??? MERGE INTO子句應指明需要合并的目的表
?????? USING ... ON 子句用于表之間的連接
?????? WHEN MATCHED THEN 子句指明當條件滿足時則對目的表執行何種操作(此處是UPDATE操作)
?????? WHEN NOT MATCHED THEN 子句指明當條件不滿足時對目的表執行何種操作(此處是INSERT操作)
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十一、更多
Oracle 用戶、對象權限、系統權限
?SQL 基礎--> ROLLUP與CUBE運算符實現數據匯總
?SQL基礎-->層次化查詢(START BY ... CONNECT BY PRIOR)
?SQL 基礎--> 視圖(CREATE VIEW)
?Oracle 常用目錄結構(10g)
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