Share via

WHERE 子句

  • 發行項

適用于：核取標示為是 Databricks SQL 檢查標示為是 Databricks Runtime

根據指定的條件限制查詢或子查詢的 子句結果 FROM 。

語法

WHERE boolean_expression

參數

  • boolean_expression

    評估為結果型 BOOLEAN 別 的任何運算式。 您可以使用 或 OR 之類的 AND 邏輯運算子來結合兩個或多個運算式。

例子

> 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;
 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;
 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;
 200 Mary null
 400  Dan   50

-- Function expression in `WHERE` clause.
> SELECT * FROM person WHERE length(name) > 3 ORDER BY id;
 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;
 200 Mary NULL
 300 Mike   80

-- Scalar Subquery in `WHERE` clause.
> SELECT * FROM person WHERE age > (SELECT avg(age) FROM person);
 300 Mike  80

-- Correlated Subquery in `WHERE` clause.
> SELECT * FROM person AS parent
   WHERE EXISTS (SELECT 1 FROM person AS child
                  WHERE parent.id = child.id
                    AND child.age IS NULL);
 200 Mary NULL