计算SQL中每列中NULL值的数量

一尘不染

计算SQL中每列中NULL值的数量

sql

我正在尝试编写一个脚本，该脚本将显示每列中非空值的数量以及表中的总行数。

我发现了几种方法可以做到这一点：

SELECT sum(case my_column when null then 1 else 0) "Null Values",
   sum(case my_column when null then 0 else 1) "Non-Null Values"
FROM my_table;

和

SELECT count(*) FROM my_table WHERE my_column IS NULL 
UNION ALL
SELECT count(*) FROM my_table WHERE my_column IS NOT NULL

但是这些要求我手动输入每个列名称。有没有一种方法可以对每个列执行此操作而不列出它们？

阅读 121

2021-05-05

共1个答案

一尘不染

正如Paolo所说，但这是一个示例：

DECLARE @TableName VARCHAR(512) = 'invoiceTbl';
DECLARE @SQL VARCHAR(1024);
WITH SQLText AS (
    SELECT 
        ROW_NUMBER() OVER (ORDER BY c.Name) AS RowNum,
        'SELECT ''' + c.name + ''', SUM(CASE WHEN ' + c.Name + ' IS NULL THEN 1 ELSE 0 END) AS NullValues FROM ' + @TableName AS SQLRow
    FROM 
        sys.tables t 
        INNER JOIN sys.columns c ON c.object_id = t.object_id
    WHERE 
        t.name = @TableName),
Recur AS (
    SELECT
        RowNum,
        CONVERT(VARCHAR(MAX), SQLRow) AS SQLRow
    FROM
        SQLText
    WHERE
        RowNum = 1
    UNION ALL
    SELECT
        t.RowNum,
        CONVERT(VARCHAR(MAX), r.SQLRow + ' UNION ALL ' + t.SQLRow)
    FROM
        SQLText t
        INNER JOIN Recur r ON t.RowNum = r.RowNum + 1
    )
SELECT @SQL = SQLRow FROM Recur WHERE RowNum = (SELECT MAX(RowNum) FROM Recur);
EXEC(@SQL);

2021-05-05