Snowpark Migration Accelerator： Where

描述

Filters the data returned by a query or subquery based on specified conditions. (Databricks SQL Language Reference WHERE (https://docs.databricks.com/en/sql/language-manual/sql-ref-syntax-qry-select-where.html))

The WHERE clause filters data by defining specific conditions that must be met. (Snowflake SQL Language Reference WHERE)

语法

WHERE <boolean_expression>

...
WHERE <predicate>
[ ... ]

示例源模式

设置数据

Databricks

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);

Snowflake

 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);

模式代码

Databricks

-- 1. Comparison operator in `WHERE` clause.
SELECT * FROM person WHERE id > 200 ORDER BY id;

-- 2. Comparison and logical operators in `WHERE` clause.
SELECT * FROM person WHERE id = 200 OR id = 300 ORDER BY id;

-- 3. IS NULL expression in `WHERE` clause.
SELECT * FROM person WHERE id > 300 OR age IS NULL ORDER BY id;

-- 4. Function expression in `WHERE` clause.
SELECT * FROM person WHERE length(name) > 3 ORDER BY id;

-- 5. `BETWEEN` expression in `WHERE` clause.
SELECT * FROM person WHERE id BETWEEN 200 AND 300 ORDER BY id;

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

-- 7. 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);

  1. Use comparison operators (such as =, >, <, >=, <=) in the WHERE clause to filter data.

ID

NAME

AGE

300

Mike

80

400

Dan

50

  1. Use comparison operators (=, <, >, <=, >=, !=) and logical operators (AND, OR, NOT) in the WHERE clause to filter data.

ID

NAME

AGE

200

Mary

null

300

Mike

80

  1. Using IS NULL in the WHERE clause to check for null values.

ID

NAME

AGE

200

Mary

null

400

Dan

50

  1. Using function expressions within a WHERE clause.

ID

NAME

AGE

100

John

30

200

Mary

null

300

Mike

80

  1. Using the BETWEEN operator in a WHERE clause to filter data based on a range of values.

ID

NAME

AGE

200

Mary

null

300

Mike

80

  1. Using a Scalar Subquery within a WHERE clause.

ID

NAME

AGE

300

Mike

80

  1. A subquery in the WHERE clause that references columns from the outer query.

ID

NAME

AGE

200

Mary

null

Snowflake

-- 1. Comparison operator in `WHERE` clause.
SELECT * FROM person WHERE id > 200 ORDER BY id;

-- 2. Comparison and logical operators in `WHERE` clause.
SELECT * FROM person WHERE id = 200 OR id = 300 ORDER BY id;

-- 3. IS NULL expression in `WHERE` clause.
SELECT * FROM person WHERE id > 300 OR age IS NULL ORDER BY id;

-- 4. Function expression in `WHERE` clause.
SELECT * FROM person WHERE length(name) > 3 ORDER BY id;

-- 5. `BETWEEN` expression in `WHERE` clause.
SELECT * FROM person WHERE id BETWEEN 200 AND 300 ORDER BY id;

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

-- 7. 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);

  1. Use comparison operators (such as =, >, <, >=, <=) in the WHERE clause to filter data.

ID

NAME

AGE

300

Mike

80

400

Dan

50

  1. Using comparison operators (such as =, <, >, <=, >=) and logical operators (such as AND, OR, NOT) in the WHERE clause to filter data.

ID

NAME

AGE

200

Mary

null

300

Mike

80

  1. Using IS NULL in the WHERE clause to check for null values.

ID

NAME

AGE

200

Mary

null

400

Dan

50

  1. Using function expressions within a WHERE clause.

ID

NAME

AGE

100

John

30

200

Mary

null

300

Mike

80

  1. Using the BETWEEN operator in a WHERE clause to filter data based on a range of values.

ID

NAME

AGE

200

Mary

null

300

Mike

80

  1. Using a Scalar Subquery within a WHERE clause.

ID

NAME

AGE

300

Mike

80

  1. Correlated Subquery in WHERE clause.

ID

NAME

AGE

200

Mary

null

已知问题

未发现任何问题