SQL Server FOR JSON:查询值列表，并在json对象中使用前两个字符作为键

-- 创建示例表
CREATE TABLE Employees (
    EmployeeID INT,
    FirstName VARCHAR(50),
    LastName VARCHAR(50)
);

-- 插入示例数据
INSERT INTO Employees (EmployeeID, FirstName, LastName)
VALUES (1, 'John', 'Doe'), (2, 'Jane', 'Smith'), (3, 'Mike', 'Johnson');

-- 查询并转换为JSON
SELECT 
    SUBSTRING(FirstName, 1, 2) AS [$.Employees.FirstName],
    LastName AS [$.Employees.LastName]
FROM Employees
FOR JSON PATH;

[
    {
        "Employees": {
            "FirstName": "Jo",
            "LastName": "Doe"
        }
    },
    {
        "Employees": {
            "FirstName": "Ja",
            "LastName": "Smith"
        }
    },
    {
        "Employees": {
            "FirstName": "Mi",
            "LastName": "Johnson"
        }
    }
]