zoukankan      html  css  js  c++  java
  • ALL比较符的用法

    ANY

    SOME

    Compares a value to each value in a list or returned by a query. Must be preceded by =, !=, >, <, <=, >=. Can be followed by any expression or subquery that returns one or more values.

    Evaluates to FALSE if the query returns no rows.

    SELECT * FROM employees
      WHERE salary = ANY
      (SELECT salary
       FROM employees
      WHERE department_id = 30)
      ORDER BY employee_id;

    ALL

    Compares a value to every value in a list or returned by a query. Must be preceded by =, !=, >, <, <=, >=. Can be followed by any expression or subquery that returns one or more values.

    Evaluates to TRUE if the query returns no rows.

    SELECT * FROM employees
      WHERE salary >=
      ALL (1400, 3000)
      ORDER BY employee_id;
     
     
    以scott/tiger 的emp表作为示例:
    scott@TEST0924> select * from emp;
     
         EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
    ---------- ---------- --------- ---------- --------- ---------- ---------- ----------
          7369 SMITH      CLERK           7902 17-DEC-80        800                    20
          7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
          7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
          7566 JONES      MANAGER         7839 02-APR-81       2975                    20
          7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
          7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
          7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
          7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
          7839 KING       PRESIDENT            17-NOV-81       5000                    10
          7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
          7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
          7900 JAMES      CLERK           7698 03-DEC-81        950                    30
          7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
          7934 MILLER     CLERK           7782 23-JAN-82       1300                    10
     
    14 rows selected.
     
    ALL:类似AND操作符,即要满足所有条件,大于所有值,即大于最大值。
    scott@TEST0924> select empno,sal from emp
      2  where sal>all(2000,3000);
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    等价于大于所有的值
    scott@TEST0924> select empno,sal from emp
      2  where sal>2000 and sal>3000;
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    等价于大于最大的那个值
    scott@TEST0924> select empno,sal from emp
      2  where sal>3000;
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
     
    如果all后面跟着子查询:
    scott@TEST0924> SELECT e2.sal FROM   emp e2 WHERE  e2.deptno = 20;
     
           SAL
    ----------
           800
          2975
          3000
          1100
          3000
     
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal > ALL (SELECT e2.sal
      4  FROM   emp e2
      5  WHERE  e2.deptno = 20);
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    等价于
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal > ALL (800,2975,3000,1100,3000);
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    等价于大于最大值:
    scott@TEST0924> SELECT e1.empno, e1.sal FROM   emp e1
      2   WHERE  e1.sal > 3000;
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    等价于
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  NOT (e1.sal <= ANY (SELECT e2.sal
      4  FROM emp e2
      5  WHERE e2.deptno = 20));
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
    也等价于
    scott@TEST0924> SELECT e1.empno, e1.sal                                                                                                            
      2  FROM   emp e1
      3  WHERE  NOT EXISTS (SELECT e2.sal
      4  FROM emp e2
      5  WHERE e2.deptno = 20
      6  AND   e1.sal <= e2.sal);
     
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
     
    如果all的子查询有返回值,则
    • "x = ALL (...)": The value must match all the values in the list to evaluate to TRUE.所有值都要匹配
    • "x != ALL (...)": The value must not match any values in the list to evaluate to TRUE.至少有一个值不匹配
    • "x > ALL (...)": The value must be greater than the biggest value in the list to evaluate to TRUE.大于最大的值
    • "x < ALL (...)": The value must be smaller than the smallest value in the list to evaluate to TRUE.小于最小的值
    • "x >= ALL (...)": The value must be greater than or equal to the biggest value in the list to evaluate to TRUE.大于等于最大的值
    • "x <= ALL (...)": The value must be smaller than or equal to the smallest value in the list to evaluate to TRUE.小于等于最小的值
    如果all的子查询返回值为0行,则
    scott@TEST0924> SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100
      2  ;
     
    no rows selected
    =ALL,按照原来的值输出
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal=ALL (SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100);
     
         EMPNO        SAL
    ---------- ----------
          7369        800
          7499       1600
          7521       1250
          7566       2975
          7654       1250
          7698       2850
          7782       2450
          7788       3000
          7839       5000
          7844       1500
          7876       1100
          7900        950
          7902       3000
          7934       1300
     
    14 rows selected.
     
    !=ALL也按照原来的值输出,但不知道按什么排序的?
    scott@TEST0924> SELECT e1.empno, e1.sal FROM   emp e1
      2  WHERE  e1.sal!=ALL (SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100);
     
         EMPNO        SAL
    ---------- ----------
          7369        800
          7902       3000
          7788       3000
          7698       2850
          7782       2450
          7839       5000
          7654       1250
          7521       1250
          7499       1600
          7876       1100
          7900        950
          7566       2975
          7934       1300
          7844       1500
     
    14 rows selected.
     
    <ALL,按原来的值降序输出
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal<ALL (SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100);
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
          7902       3000
          7788       3000
          7566       2975
          7698       2850
          7782       2450
          7499       1600
          7844       1500
          7934       1300
          7521       1250
          7654       1250
          7876       1100
          7900        950
          7369        800
     
    14 rows selected.
    <=ALL和<ALL一样按原来的值降序输出
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal<=ALL (SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100);
     
         EMPNO        SAL
    ---------- ----------
          7839       5000
          7902       3000
          7788       3000
          7566       2975
          7698       2850
          7782       2450
          7499       1600
          7844       1500
          7934       1300
          7521       1250
          7654       1250
          7876       1100
          7900        950
          7369        800
     
    14 rows selected.
     
    >ALL和>=ALL,按原来的升序输出
    scott@TEST0924> SELECT e1.empno, e1.sal
      2  FROM   emp e1
      3  WHERE  e1.sal > ALL (SELECT e2.sal FROM emp e2 WHERE e2.deptno = 100);
     
         EMPNO        SAL
    ---------- ----------
          7369        800
          7900        950
          7876       1100
          7521       1250
          7654       1250
          7934       1300
          7844       1500
          7499       1600
          7782       2450
          7698       2850
          7566       2975
          7788       3000
          7902       3000
          7839       5000
     
    14 rows selected.
     
  • 相关阅读:
    微信小程序wx.chooseImage和wx.previewImage的综合使用(图片上传不限制最多张数)
    js数组与字符串之间的相互转换
    微信小程序wx.previewImage实用案例(交流QQ群:604788754)
    PHP:第一章——PHP中的魔术常量
    小程序模板嵌套以及相关遍历数据绑定
    6 大主流 Web 框架优缺点对比:15篇前端热文回看
    通俗地讲,Netty 能做什么?
    Netty
    为什么选择Netty
    linux下gsoap的初次使用 -- c风格加法实例
  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13317167.html
Copyright © 2011-2022 走看看