Question

是否有一种简单的方法可以从（长）数组中进行选择？我想要这样的东西

<img src="/path/to/image.php" />

但是我希望所有公民身份都作为列，而所有日期（从2000年到2018年）都作为行，因此我可以删除where子句。

Answer 1

添加独特将为您提供唯一的公民列表

SELECT distinct citizenship
FROM table 
WHERE year(date) >= 2000 and year(date) <= 2018

Answer 2

想要使用PIVOT列的声音。

这里是我想要的...（在SQL Server中）请参阅这篇文章：https://www.databasejournal.com/features/mssql/converting-rows-to-columns-pivot-and-columns-to-rows-unpivot-in-sql-server.html

可能会应用于您...

    --Declare necessary variables
DECLARE   @SQLQuery AS NVARCHAR(MAX)
DECLARE   @PivotColumns AS NVARCHAR(MAX)

--Get unique values of pivot column  
SELECT   @PivotColumns= COALESCE(@PivotColumns + ',','') + QUOTENAME([citizenship])
FROM (SELECT DISTINCT [citizenship] FROM [dbo].[table]) AS PivotExample


--Create the dynamic query with all the values for 
--pivot column at runtime
SET   @SQLQuery = 
    N'SELECT [Year], ' +   @PivotColumns + '
    FROM (SELECT [citizenship], YEAR([Date]) AS [Year], COUNT(1) As Counter 
          FROM [Table] GROUP BY [citizenship], YEAR([Date])) AS A
    PIVOT( SUM(Counter) 
          FOR [citizenship] IN (' + @PivotColumns + ')) AS P'

SELECT   @SQLQuery
--Execute dynamic query
EXEC sp_executesql @SQLQuery

从数组中选择SQL

2 个答案: