将 bigint unsigned 列转换为 bigint signed 失败

Question

我在 MySql 数据库版本 7.0

中遇到语法错误

SELECT
    r.id,
    r.number,
    r.numbertype,
    r.forhandler,
    LAG(r.number) OVER (PARTITION BY r.numbertype ORDER BY r.number) AS last_row_number,
    LEAD(r.number) OVER (PARTITION BY r.numbertype ORDER BY r.number) AS next_row_number,
    r.number -(LAG(r.number) OVER (PARTITION BY r.numbertype ORDER BY r.number)) AS gap_last_rk,
    CAST (r.number-(LEAD(r.number) OVER (PARTITION BY r.numbertype ORDER BY r.`number`)) AS BIGINT SIGNED)  AS gap_next_rk

FROM admin.numberranges r
WHERE r.status=2
ORDER BY r.number;

语法错误在我的 CAST 部分。我的列 NUMBER 是一个 BIG INT UNSIGNED。

我也试过转换-:(

Error Code: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'BIGINT SIGNED) AS neg_number

Answer 1

首先，您在 CAST 之后有一个 space，这可能会导致其他 errors/issues 解析您的问题。你必须使用 CAST(...)。其次，类型 BIGINT SIGNED 不被允许，检查列表中的 CAST(expr AS type)。当你想要一个带符号的数字时，你可以使用 SIGNED 或 SIGNED INTEGER 类型，如文档中所述：

The type can be one of the following values:

[...]

SIGNED [INTEGER]

请参阅以下有关如何使用 CAST() 函数的查询（示例运行 on MySQL 8.0.23，MariaDB 的结果可能不同，但类型限制都差不多，见MySQL documentation of CONVERT(expr, type)):

mysql> EXPLAIN Dummy;
+-------+-----------------+------+-----+---------+-------+
| Field | Type            | Null | Key | Default | Extra |
+-------+-----------------+------+-----+---------+-------+
| Test  | bigint unsigned | YES  |     | NULL    |       |
+-------+-----------------+------+-----+---------+-------+
1 row in set (0.01 sec)

mysql> SELECT Test, CAST(Test AS BIGINT SIGNED) FROM Dummy;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that
                    corresponds to your MySQL server version for the right syntax
                    to use near 'BIGINT SIGNED) FROM Dummy' at line 1
mysql> SELECT Test, CAST(Test AS SIGNED) FROM Dummy;
+------+----------------------+
| Test | CAST(Test AS SIGNED) |
+------+----------------------+
| 1234 |                 1234 |
+------+----------------------+
1 row in set (0.00 sec)

将 bigint unsigned 列转换为 bigint signed 失败

Conversion of bigint unsigned column to bigint signed fails

mariasql