any/all
用法
any 和 all 关键字用于 where 或 having 子句。
where/having col optr any(sub_query)
where/having col optr all(sub_query)
其中 optr 是比较运算符,sub_query 是一个 SQL 查询或者向量。
any/all 关键字将比较运算符前的操作数(通常是某列的值)与子查询结果集或向量中的值一一比较:
-
any:若存在满足条件的子查询结果或向量值,则返回 true,否则为 false。
-
all:若所有子查询结果或向量值都满足比较条件,则返回 true,否则返回 false。
注:
-
“= any“ 等价于 “in”;”= all” 等价于 “!= any”;
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SQL 的 any / all 谓词和内置函数 any / all 功能类似但不同。前者用于值比较,后者用于判断布尔值。
下面以两个语句来说明区别:
-
SQL 中的 any 谓词:
x > any([n1,n2,n3])
-
内置 any 函数:
any([x>n1, x>n2, x>n3])
例子
sym = `C`MS`MS`MS`IBM`IBM`C`C`C$SYMBOL
price= 49.6 29.46 29.52 30.02 174.97 175.23 50.76 50.32 51.29
qty = 2200 1900 2100 3200 6800 5400 1300 2500 8800
timestamp = [09:34:07,09:36:42,09:36:51,09:36:59,09:32:47,09:35:26,09:34:16,09:34:26,09:38:12]
t1 = table(timestamp, sym, qty, price);
t2 = table(`C`MS`IBM as sym, 1 0 1 as flag)
select * from t1 where sym = any(select sym from t2 where flag=1)
timestamp | sym | qty | price |
---|---|---|---|
09:34:07 | C | 2,200 | 49.6 |
09:32:47 | IBM | 6,800 | 174.97 |
09:35:26 | IBM | 5,400 | 175.23 |
09:34:16 | C | 1,300 | 50.76 |
09:34:26 | C | 2,500 | 50.32 |
09:38:12 | C | 8,800 | 51.29 |
select * from t1 where sym != all(select sym from t2 where flag = 1)
timestamp | sym | qty | price |
---|---|---|---|
09:36:42 | MS | 1,900 | 29.46 |
09:36:51 | MS | 2,100 | 29.52 |
09:36:59 | MS | 3,200 | 30.02 |
t3 = select wavg(price, qty) as wavg from t1 group by sym
select * from t1 where price >= all(select wavg from t3)
timestamp | sym | qty | price |
---|---|---|---|
09:35:26 | IBM | 5,400 | 175.23 |
select * from t1 where price >= any(select wavg from t3)
timestamp | sym | qty | price |
---|---|---|---|
09:34:07 | C | 2,200 | 49.6 |
09:36:59 | MS | 3,200 | 30.02 |
09:32:47 | IBM | 6,800 | 174.97 |
09:35:26 | IBM | 5,400 | 175.23 |
09:34:16 | C | 1,300 | 50.76 |
09:34:26 | C | 2,500 | 50.32 |
09:38:12 | C | 8,800 | 51.29 |