SQL Server循环并在sql中插入

Question

我需要在SQL中运行一个循环.谷歌这有点奇怪的原因有点困难.在SQL Server中,我只是把它放在SQL Server Managment Studio的查询编辑器中

DECLARE @z_start INT
SET @z_start = 0
DECLARE @z_end INT
SET @z_end = 0

WHILE (@z_start <= 14) BEGIN
    IF(@z_start != 0 AND @z_end != 14)
        WHILE (@z_end <= 14) BEGIN
            INSERT INTO [campusMap].[dbo].[zoom_levels] ([zoom_start],[zoom_end]) VALUES (@z_start,@z_end)
            SET @z_end = @z_end + 1
        END
        SET @z_start = @z_start + 1
    END
END

我想做的就是将zoom_start和zoom_end设置为(0,0)到(14,14)仅跳过(0,14),因为它已经在表中.

我想我很亲密.有谁知道它在哪里？谢谢.干杯 - 杰里米

Answer 1

您可以使用CTE(或预先存在的数字表)并一次添加所需的所有行,而不是执行嵌套循环并一次插入每一行:

;WITH Numbers (Number) AS 
(
    SELECT 0 
    UNION ALL
    SELECT 1 + Number FROM Numbers 
    WHERE 1 + Number <= 14
)
INSERT INTO [campusMap].[dbo].[zoom_levels] ([zoom_start],[zoom_end])
SELECT n1.Number, n2.Number 
FROM
    Numbers n1 CROSS JOIN
    Numbers n2
WHERE
    NOT (n1.Number = 0 AND n2.Number = 14)

SQL中的基于集合的操作通常比程序性的逐行方法更清晰,更易于理解.