Su, Xiaomeng 04d4597cf3 dli_sqlreference_0511_version

Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Su, Xiaomeng <suxiaomeng1@huawei.com>
Co-committed-by: Su, Xiaomeng <suxiaomeng1@huawei.com>

2023-11-02 14:34:08 +00:00

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WITH...AS

Function

This statement is used to define the common table expression (CTE) using WITH...AS to simplify the query and make the result easier to read and maintain.

Syntax

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WITH cte_name AS (select_statement) sql_containing_cte_name;

Keyword

cte_name: Name of a public expression. The name must be unique.
select_statement: complete SELECT clause.
sql_containing_cte_name: SQL statement containing the defined common expression.

Precautions

A CTE must be used immediately after it is defined. Otherwise, the definition becomes invalid.
Multiple CTEs can be defined by WITH at a time. The CTEs are separated by commas and the CTEs defined later can quote the CTEs defined earlier.

Example

Define SELECT courseId FROM course_info WHERE courseName = 'Biology' as CTE nv and use nv as the SELECT statement in future queries.

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WITH nv AS (SELECT courseId FROM course_info WHERE courseName = 'Biology') SELECT DISTINCT courseId FROM nv;

Parent topic: Spark SQL Syntax Reference

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