縮排

Created: November-22, 2018

沒有被廣泛接受的標準。每個人都同意的是，將所有內容壓縮成一行是不好的：

SELECT d.Name, COUNT(*) AS Employees FROM Departments AS d JOIN Employees AS e ON d.ID = e.DepartmentID WHERE d.Name != 'HR' HAVING COUNT(*) > 10 ORDER BY COUNT(*) DESC;

至少，將每個子句放入一個新行，如果它們變得太長則拆分行：

SELECT d.Name,
       COUNT(*) AS Employees
FROM Departments AS d
JOIN Employees AS e ON d.ID = e.DepartmentID
WHERE d.Name != 'HR'
HAVING COUNT(*) > 10
ORDER BY COUNT(*) DESC;

有時，引入子句的 SQL 關鍵字之後的所有內容都縮排到同一列：

SELECT   d.Name,
         COUNT(*) AS Employees
FROM     Departments AS d
JOIN     Employees AS e ON d.ID = e.DepartmentID
WHERE    d.Name != 'HR'
HAVING   COUNT(*) > 10
ORDER BY COUNT(*) DESC;

（這也可以在正確對齊 SQL 關鍵字時完成。）

另一種常見的風格是將重要的關鍵字放在他們自己的行上：

SELECT
    d.Name,
    COUNT(*) AS Employees
FROM
    Departments AS d
JOIN
    Employees AS e
    ON d.ID = e.DepartmentID
WHERE
    d.Name != 'HR'
HAVING
    COUNT(*) > 10
ORDER BY
    COUNT(*) DESC;

垂直對齊多個相似表示式可提高可讀性：

SELECT Model,
       EmployeeID
FROM Cars
WHERE CustomerID = 42
  AND Status     = 'READY';

使用多行會使 SQL 命令更難嵌入到其他程式語言中。但是，許多語言都有多線字串的機制，例如 C#中的 @"..."，Python 中的 """...""" 或 C++中的 R"(...)"。