随机值未插入到 SQLite 表中

Question

我在 SQLite 中创建了一个数据库和一个表。架构是这样的：

CREATE TABLE Students (
    StudentID INTEGER PRIMARY KEY,
    FirstName TEXT NOT NULL,
    LastName TEXT NOT NULL,
    Gender TEXT CHECK (Gender IN ('Male', 'Female', 'Other')),
    Age INTEGER,
    RegistrationDate DATE
);

我尝试运行一些查询来手动插入 1000 行数据，但年龄和数据给出了奇怪的值。 这是查询：

WITH RECURSIVE
  cnt(x) AS (
     SELECT 1
     UNION ALL
     SELECT x+1 FROM cnt
     WHERE x<1000
  )
INSERT INTO Students (FirstName, LastName, Gender, Age, RegistrationDate)
SELECT
    'FirstName' || x,
    'LastName' || x,
    CASE WHEN x % 3 = 0 THEN 'Male' WHEN x % 3 = 1 THEN 'Female' ELSE 'Other' END,
    CAST(18 + ROUND(RANDOM() * 10) AS INTEGER), -- Age between 18 and 28
    DATE('now', '-' || ROUND(RANDOM() * 365, 0) || ' days') -- Random registration date in the last year
FROM cnt;

这是我从学生中选择*时的值的结果；

1|FirstName1|LastName1|Female|-9223372036854775808|
2|FirstName2|LastName2|Other|9223372036854775807|
3|FirstName3|LastName3|Male|-9223372036854775808|
4|FirstName4|LastName4|Female|-9223372036854775808|
5|FirstName5|LastName5|Other|9223372036854775807|
6|FirstName6|LastName6|Male|-9223372036854775808|
7|FirstName7|LastName7|Female|-9223372036854775808|
8|FirstName8|LastName8|Other|-9223372036854775808|

Answer 1

阅读文档：

random() 函数返回 -9223372036854775808 和 +9223372036854775807 之间的伪随机整数。

所以，解决方案是使用模：

ABS(RANDOM()) % 11 + 18, -- Age between 18 and 28

日期也类似：

DATE('now', '-' || (ABS(RANDOM()) % 366) || ' days') -- Random registration date in the last year

Answer 2

我已经使用模数（％）更新了逻辑。这是示例代码：

WITH RECURSIVE
  cnt(x) AS (
     SELECT 1
     UNION ALL
     SELECT x+1 FROM cnt
     WHERE x<1000
  )
INSERT INTO Students (FirstName, LastName, Gender, Age, RegistrationDate)
SELECT
    'FirstName' || x,
    'LastName' || x,
    CASE WHEN x % 3 = 0 THEN 'Male' WHEN x % 3 = 1 THEN 'Female' ELSE 'Other' END,
    18 + ABS(CAST(RANDOM() % 11 AS INTEGER)), -- Age between 18 and 28
    DATE('now', '-' || (ABS(RANDOM()) % 365) || ' days') -- Random registration date in the last year
FROM cnt;

这是示例输出：

这是dbfiddle