Where
ينطبق على:
التحقق من Databricks SQL Databricks Runtime
يحد من FROM نتائج عبارة استعلام أو استعلام فرعي استنادا إلى الشرط المحدد.
بناء الجمله
WHERE boolean_expression
معلمات
-
أي تعبير يتم تقييمه إلى نوع
BOOLEANنتيجة . يمكنك دمج تعبيرين أو أكثر باستخدام عوامل التشغيل المنطقية مثلANDأوOR.
امثله
> 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