oracle-analysis

痛定思痛。 2023-10-18 16:02 107阅读 0赞

#### oracle-analysis ####

CREATE TABLE EMPLOY
    (
        NAME    VARCHAR2(10),  --姓名
        DEPT    VARCHAR2(10),  --部门
        SALARY  NUMBER         --工资
    );
     
    INSERT INTO EMPLOY VALUES ('张三','市场部',4000);
    INSERT INTO EMPLOY VALUES ('赵红','技术部',2000);
    INSERT INTO EMPLOY VALUES ('李四','市场部',5000);
    INSERT INTO EMPLOY VALUES ('李白','技术部',5000);
    INSERT INTO EMPLOY VALUES ('王五','市场部',NULL);
    INSERT INTO EMPLOY VALUES ('王蓝','技术部',4000);
     
    SELECT
        ROW_NUMBER() OVER(ORDER BY SALARY) AS 序号,
        NAME                               AS 姓名,
        DEPT                               AS 部门,
        SALARY                             AS 工资
    FROM EMPLOY;
    /*
    查询结果如下：
     
    序号       姓名       部门      工资
    1          赵红       技术部    2000
    2          张三       市场部    4000
    3          王蓝       技术部    4000
    4          李四       市场部    5000
    5          李白       技术部    5000
    6          王五       市场部    (null)
    */ 
    SELECT
        ROW_NUMBER() OVER( ORDER BY DEPT) AS 序号,
        NAME                               AS 姓名,
        DEPT                               AS 部门,
        SALARY                             AS 工资
    FROM EMPLOY;
    /*
    如果不在over中加入限制分组/作用域，那就是默认整个集合
    ROW_NUMBER() 从下面的序号一列中可以看出
    1	赵红	技术部	2000
    2	李白	技术部	5000
    3	王蓝	技术部	4000
    4	王五	市场部	
    5	张三	市场部	4000
    6	李四	市场部	5000
    */
    SELECT
        ROW_NUMBER() OVER(PARTITION BY dept ORDER BY DEPT) AS 序号,
        NAME                               AS 姓名,
        DEPT                               AS 部门,
        SALARY                             AS 工资
    FROM EMPLOY;
    /*
    加上PARTITION BY dept 根据部门重新排序
    1	赵红	技术部	2000
    2	李白	技术部	5000
    3	王蓝	技术部	4000
    1	王五	市场部	
    2	张三	市场部	4000
    3	李四	市场部	5000
    */
    SELECT
        ROW_NUMBER() OVER(ORDER BY dept,SALARY NULLS first) AS 序号,
        NAME                               AS 姓名,
        DEPT                               AS 部门,
        SALARY                             AS 工资,
    		round(AVG(SALARY) OVER(PARTITION BY dept),2) AS 部门平均工资,
    		AVG(SALARY) OVER() AS 公司平均工资
    FROM EMPLOY;
    /*
    加上nulls first后可以使得null的数据排在前面，
    因为这里加上了(AVG(SALARY) OVER(PARTITION BY dept),2)
    但也是排在部门的前面
    1	赵红	技术部	2000	3666.67	4000
    2	王蓝	技术部	4000	3666.67	4000
    3	李白	技术部	5000	3666.67	4000
    4	王五	市场部		4500	4000
    5	张三	市场部	4000	4500	4000
    6	李四	市场部	5000	4500	4000
    */
    SELECT
        ROW_NUMBER() OVER(ORDER BY SALARY DESC NULLS FIRST)    AS RN,
        RANK() OVER(ORDER BY SALARY DESC NULLS FIRST)          AS RK,
        DENSE_RANK() OVER(ORDER BY SALARY DESC NULLS FIRST)    AS D_RK,
        NAME                                                   AS 姓名,
        DEPT                                                   AS 部门,
        SALARY                                                 AS 工资
    FROM EMPLOY;
    /*
    rank函数的作用是排名，如果有并列的名次那么会直接跳到下一名，但是DENSE_RANK就不会了，并列的名次，下面的名次依旧只是加一
    查询结果如下：
     
    RN  RK   D_RK     姓名       部门       工资
    1     1     1     王五       市场部    (null)
    2     2     2     李四       市场部    5000
    3     2     2     李白       技术部    5000
    4     4     3     张三       市场部    4000
    5     4     3     王蓝       技术部    4000
    6     6     4     赵红       技术部    2000
    */ 
    SELECT
        NAME                                                                AS 姓名,
        SALARY                                                              AS 工资,
        SUM(SALARY) OVER(ORDER BY SALARY NULLS FIRST 
                  ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)         AS 小于本人工资的总额,
        SUM(SALARY) OVER(ORDER BY SALARY NULLS FIRST 
                  ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)         AS 大于本人工资的总额,
        SUM(SALARY) OVER(ORDER BY SALARY NULLS FIRST 
                  ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS 工资总额1,
        SUM(SALARY) OVER()                                                  AS 工资总额2
    FROM EMPLOY;
    DELETE FROM EMPLOY;  
    INSERT INTO EMPLOY VALUES ('张三','市场部',2000);  
    INSERT INTO EMPLOY VALUES ('赵红','技术部',2400);  
    INSERT INTO EMPLOY VALUES ('李四','市场部',3000);  
    INSERT INTO EMPLOY VALUES ('李白','技术部',3200);  
    INSERT INTO EMPLOY VALUES ('王五','市场部',4000);  
    INSERT INTO EMPLOY VALUES ('王蓝','技术部',5000);   
      
    SELECT
        NAME                                                                              AS 姓名,
        DEPT                                                                              AS 部门,
        SALARY                                                                            AS 工资,
        FIRST_VALUE(SALARY IGNORE NULLS) OVER(PARTITION BY DEPT)                  AS 部门最低工资,
        NTH_VALUE(SALARY, 2) OVER(PARTITION BY DEPT)                          AS 部门倒数第二工资,
        LAST_VALUE(SALARY RESPECT NULLS) OVER(PARTITION BY DEPT)                  AS 部门最高工资,
        SUM(SALARY) OVER(ORDER BY SALARY ROWS BETWEEN 1 PRECEDING  AND 1 FOLLOWING)     AS "ROWS", 
        SUM(SALARY) OVER(ORDER BY SALARY RANGE BETWEEN 500 PRECEDING AND 500 FOLLOWING) AS "RANGE" 
    FROM EMPLOY;
    
    /*
    
    rows查询结果
    查询结果如下：
     
    姓名       工资       小于本人工资的总额  大于本人工资的总额    工资总额1     工资总额2
    王五       (null)     (null)              20000                 20000         20000
    赵红       2000       2000                20000                 20000         20000
    张三       4000       6000                18000                 20000         20000
    王蓝       4000       10000               14000                 20000         20000
    李四       5000       15000               10000                 20000         20000
    李白       5000       20000               5000                  20000         20000
    ROWS BETWEEN <上限条件> AND <下限条件>
     
    其中“上限条件”可以是如下关键字：
    UNBOUNDED PRECEDING
    <number>  PRECEDING
    CURRENT ROW
     
    “下线条件”可以是如下关键字：
    CURRENT ROW
    <number> FOLLOWING
    UNBOUNDED FOLLOWING
    
    以上关键字都是相对当前行的，UNBOUNDED PRECEDING表示当前行前面的所有行，也就是说没有上限；<number> PRECEDING表示从当前行开始到它前面的<number>行为止，例如，number=2，表示的是当前行前面的2行；CURRENT ROW表示当前行
    
    
    range查询结果
    查询结果如下：  
       
    姓名    部门      工资    部门最低工资    部门倒数第二工资   部门最高工资       ROWS    RANGE  
    张三    市场部    2000    2000            3000               4000               4400    4400
    赵红    技术部    2400    3200            5000               2400               7400    4400
    李四    市场部    3000    2000            3000               4000               8600    6200
    李白    技术部    3200    3200            5000               2400               10200   6200
    王五    市场部    4000    2000            3000               4000               12200   4000
    王蓝    技术部    5000    3200            5000               2400               9000    5000
    
    上面SQL的RANGE子句的作用是定义一个工资范围，这个范围的上限是当前行的工资-500，下限是当前行工资+500。例如：李四的工资是3000，所以上限是3000-500=2500，下限是3000+500=3500，那么有谁的工资在2500-3500这个范围呢？只有李四和李白，所以RANGE列的值就是3000(李四)+3200(李白)=6200。以上就是ROWS和RANGE得区别。
    上面的 SQL 还用到了FIRST_VALUE，NTH_VALUE 和 LAST_VALUE 三个函数，它们的作用也非常简单，用来求OVER定义集合的最小值，第 n 行的值和最大值。值得注意的是这两个函数有个关键字，IGNORE NULLS 或 RESPECT NULLS，它们的作用正如它们的名字一样，用来忽略NULL值和考虑NULL值。
    
    */ 
    SELECT
        NAME                                                     AS 姓名,
        SALARY                                                   AS 工资,
        LAG(SALARY,0) OVER(ORDER BY SALARY)                      AS LAG0,
        LAG(SALARY) OVER(ORDER BY SALARY)                        AS LAG1,
        LAG(SALARY,2) OVER(ORDER BY SALARY)                      AS LAG2,
        LAG(SALARY,3 ,0) IGNORE NULLS OVER(ORDER BY SALARY)      AS LAG3,
        LAG(SALARY,4, -1) RESPECT NULLS OVER(ORDER BY SALARY)    AS LAG4,
        LEAD(SALARY) OVER(ORDER BY SALARY)                       AS LEAD
    FROM EMPLOY;
    /*
    姓名       工资       LAG0      LAG1      LAG2      LAG3      LAG4      LEAD
    张三       2000       2000      (null)   (null)       0       -1        2400
    赵红       2400       2400       2000    (null)       0       -1        3000
    李四       3000       3000       2400     2000       0        -1        3200
    李白       3200       3200       3000     2400       2000     -1        4000
    王五       4000       4000       3200     3000       2400     2000      5000
    王蓝       5000       5000       4000     3200       3000     2400      (null)
    
    解释：
    LAG(表达式或字段,偏移量, 默认值) IGNORE NULLS或RESPECT NULLS
    LAG是向下偏移，LEAD是向上偏移
    */

CREATE TABLE price_history
    (
        security_id    NUMBER(10, 0),
        price          NUMBER(10, 4),
        price_date     DATE,
    	rank           NUMBER(2, 0)
    	/*
    	存放股票历史价格
    	*/
    );
    
    CREATE TABLE price
    (
        security_id    NUMBER(10, 0),
        price          NUMBER(10, 4)
    		/*
    		存放最新价格
    		*/
    );
    insert all 
    into price_history(security_id,price,price_date,rank) values(1,10,CURRENT_DATE,1)
    into price_history(security_id,price,price_date,rank) values(1,8,CURRENT_DATE-1,3)
    into price_history(security_id,price,price_date,rank) values(1,9,CURRENT_DATE+1,2)
    into price_history(security_id,price,price_date,rank) values(2,10,CURRENT_DATE,2)
    into price_history(security_id,price,price_date,rank) values(2,11,CURRENT_DATE-1,1)
    into price_history(security_id,price,price_date,rank) values(3,13,CURRENT_DATE+2,3)
    into price_history(security_id,price,price_date,rank) values(3,10,CURRENT_DATE-1,1)
    into price_history(security_id,price,price_date,rank) values(3,10,CURRENT_DATE+2,2)
    into price_history(security_id,price,price_date,rank) values(2,10,CURRENT_DATE-2,3)
    into price_history(security_id,price,price_date,rank) values(4,10,CURRENT_DATE,2)
    into price_history(security_id,price,price_date,rank) values(4,10,CURRENT_DATE+3,3)
    into price_history(security_id,price,price_date,rank) values(4,10,CURRENT_DATE-1,1)
    select CURRENT_DATE from dual;
    select * from price_history;
    MERGE INTO price p
    USING (
      SELECT security_id, price FROM (
        SELECT
          ROW_NUMBER() OVER(PARTITION BY security_id ORDER BY price_date DESC, rank DESC) AS ROW_ID,
          security_id,
          price
        FROM
          price_history
      ) WHERE ROW_ID = 1
    ) ph
    ON (p.security_id = ph.security_id)  
    WHEN MATCHED THEN UPDATE SET p.price = ph.price
    WHEN NOT MATCHED THEN INSERT VALUES (ph.security_id, ph.price);
    /*
    以下是对上述语句的解释
    */
    /*下面的集合按照security_id编号，在相同的security_id里面会从1开始编码*/
    SELECT
          ROW_NUMBER() OVER(PARTITION BY security_id ORDER BY price_date DESC, rank DESC) AS ROW_ID,
          security_id,
          price
        FROM
          price_history
    /*然后选出相同的security_id，也就是row_id为1*/
      SELECT security_id, price FROM (
        SELECT
          ROW_NUMBER() OVER(PARTITION BY security_id ORDER BY price_date DESC, rank DESC) AS ROW_ID,
          security_id,
          price
        FROM
          price_history
      ) WHERE ROW_ID = 1
    /*最后使用merge语句，如果满足条件也就是在最新价格表中存在记录，我们就更新，没有就插入*/
    MERGE INTO price p
    USING (
      SELECT security_id, price FROM (
        SELECT
          ROW_NUMBER() OVER(PARTITION BY security_id ORDER BY price_date DESC, rank DESC) AS ROW_ID,
          security_id,
          price
        FROM
          price_history
      ) WHERE ROW_ID = 1
    ) ph
    ON (p.security_id = ph.security_id)  
    WHEN MATCHED THEN UPDATE SET p.price = ph.price
    WHEN NOT MATCHED THEN INSERT VALUES (ph.security_id, ph.price);
    
    SELECT   
        security_id,  
        price_date,  
    		price,
        price - NVL(LAG(price) OVER(PARTITION BY security_id ORDER BY price_date), 0)
    FROM price_history;
    
    /*
    假设现在我们有下面的表用来存放交易记录，现在我们要做一个报表，查询一下每相邻两次交易记录的 price 的差值，也就是第二条记录的 price 减去第一条的 price，第三条减去第二条
    我们可以利用lag进行向下偏移，然后使用当前价格减去上一条记录的价格
    1	2019-03-23 12:02:57	8	8
    1	2019-03-24 12:02:57	10	2
    1	2019-03-25 12:02:57	9	-1
    2	2019-03-22 12:02:57	10	10
    2	2019-03-23 12:02:57	11	1
    2	2019-03-24 12:02:57	10	-1
    3	2019-03-23 12:02:57	10	10
    3	2019-03-26 12:02:57	10	0
    3	2019-03-26 12:02:57	13	3
    4	2019-03-23 12:02:57	10	10
    4	2019-03-24 12:02:57	10	0
    4	2019-03-27 12:02:57	10	0
    */

oracle-analysis

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