SQL

Question

我正在尝试使用 WITH 在执行 INSERT INTO 时为查询声明一个变量。我正在关注，它为 SELECT 查询提供了以下示例：

WITH myconstants (var1, var2) as (
   values (5, 'foo')
)
SELECT *
FROM somewhere, myconstants
WHERE something = var1
   OR something_else = var2;

我尝试了以下但没有成功：

playground> CREATE TABLE foo (id numeric)
CREATE TABLE

playground> WITH consts (x) AS (VALUES (2)) INSERT INTO foo VALUES (x)
column "x" does not exist
LINE 1: WITH consts (x) AS (VALUES (2)) INSERT INTO foo VALUES (x)
                                                                ^

playground> WITH consts (x) AS (VALUES (2)) INSERT INTO foo VALUES (consts.x)
missing FROM-clause entry for table "consts"
LINE 1: ...consts (x) AS (VALUES (2)) INSERT INTO foo VALUES (consts.x)
                                                              ^

playground> WITH consts (x) AS (VALUES (2)) INSERT INTO foo VALUES (consts.x) FROM consts
syntax error at or near "FROM"
LINE 1: ...AS (VALUES (2)) INSERT INTO foo VALUES (consts.x) FROM const...
                                                             ^

playground> WITH consts (x) AS (VALUES (2)) INSERT INTO foo FROM consts VALUES (consts.x)
syntax error at or near "FROM"
LINE 1: WITH consts (x) AS (VALUES (2)) INSERT INTO foo FROM consts ...
                                                        ^

请注意，我是 SQL 的初学者，因此我希望避免使用暗示使用 PLPGSQL

的解决方案

Answer 1

我想你想要：

WITH consts (x) AS (VALUES (2)) INSERT INTO foo SELECT x FROM consts

即：WITH 子句创建一个 派生的 table，然后您可以在主查询中使用它；所以你实际上需要 SELECT ... FROM 常见的 table 表达式。

SQL - 使用 WITH 在 INSERT INTO 上声明变量

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