WHERE 子句 - 亚马逊 OpenSearch 服务

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WHERE 子句

注意

要查看哪些 AWS 数据源集成支持此SQL命令，请参阅支持的 OpenSearch SQL命令和函数。

该WHERE子句用于根据指定条件限制查询或子查询的子FROM句的结果。

语法 

WHERE boolean_expression

参数

  • 布尔表达式

    指定任何计算结果类型为 boolean 的表达式。

    可以使用逻辑运算符 (AND,OR) 将两个或多个表达式组合在一起。

示例

CREATE TABLE person (id INT, name STRING, age INT);
INSERT INTO person VALUES
(100, 'John', 30),
(200, 'Mary', NULL),
(300, 'Mike', 80),
(400, 'Dan',  50);

-- Comparison operator in `WHERE` clause.
SELECT * FROM person WHERE id > 200 ORDER BY id;
+---+----+---+
| id|name|age|
+---+----+---+
|300|Mike| 80|
|400| Dan| 50|
+---+----+---+

-- Comparison and logical operators in `WHERE` clause.
SELECT * FROM person WHERE id = 200 OR id = 300 ORDER BY id;
+---+----+----+
| id|name| age|
+---+----+----+
|200|Mary|null|
|300|Mike|  80|
+---+----+----+

-- IS NULL expression in `WHERE` clause.
SELECT * FROM person WHERE id > 300 OR age IS NULL ORDER BY id;
+---+----+----+
| id|name| age|
+---+----+----+
|200|Mary|null|
|400| Dan|  50|
+---+----+----+

-- Function expression in `WHERE` clause.
SELECT * FROM person WHERE length(name) > 3 ORDER BY id;
+---+----+----+
| id|name| age|
+---+----+----+
|100|John|  30|
|200|Mary|null|
|300|Mike|  80|
+---+----+----+

-- `BETWEEN` expression in `WHERE` clause.
SELECT * FROM person WHERE id BETWEEN 200 AND 300 ORDER BY id;
+---+----+----+
| id|name| age|
+---+----+----+
|200|Mary|null|
|300|Mike|  80|
+---+----+----+

-- Scalar Subquery in `WHERE` clause.
SELECT * FROM person WHERE age > (SELECT avg(age) FROM person);
+---+----+---+
| id|name|age|
+---+----+---+
|300|Mike| 80|
+---+----+---+
 
-- Correlated Subquery in `WHERE` clause.
SELECT id FROM person
WHERE exists (SELECT id FROM person where id = 200);
+---+----+----+
|id |name|age |
+---+----+----+
|200|Mary|null|
+---+----+----+