如何将非 NULL 的列计入相同的 table？

Question

如何计算非 Null 或零的 table 列并将结果插入 "Count" 列，如 Mysql 下面的 table?

 column1 | column2 | column3 | column4 | Count
    3        2          4         2        4
    2        2          3         0        3     
    3        0          5         2        3
    0        0          2         3        2
    0        0          6         2        2

Answer 1

select
    CT.Column1,
    CT.Column2,
    CT.Column3,
    CT.Column4,
    (
        select count(*)
        from (values (CT.column1), (CT.column2), (CT.column3), (CT.column4)) as v(col)
        where v.col is not null
    ) as Count
from customtable as CT

Answer 2

一种方法是简单地使用 case 语句：

编辑：

要更新 table_name 中的 cnt 列，您可以使用：

update table_name 
set cnt = (case when column1 is null or column1 = 0 then 0 else 1 end + 
           case when column2 is null or column2 = 0 then 0 else 1 end +
           case when column3 is null or column3 = 0 then 0 else 1 end +
           case when column4 is null or column4 = 0 then 0 else 1 end)

Answer 3

首先在第 3 行的 table 中，预期计数是 3，对吗？一种肮脏的做法是将测试的整数值求和为 NULL 列（布尔值，因为 int 是 1 或 0 ）：

SELECT
Column1, Column2, Column3,  Column4,
 (CAST(column1 is not null AS SIGNED INTEGER) +
    CAST(column2 is not null AS SIGNED INTEGER) +
    CAST(column3 is not null AS SIGNED INTEGER) + 
    CAST(column4 is not null AS SIGNED INTEGER)) as count
FROM (
    SELECT 3 as column1,2 as column2,4 as column3,2 as column4
    union select 2,2,3,NULL
    union select 3,NULL,5,2
    union select NULL,NULL,2,3
    union select NULL,NULL,6,2
) as YourTable

Answer 4

试试这个查询。

更新集=sum(COUNT()-COUNT(column1) + COUNT()-COUNT(column2) + COUNT()-COUNT(column3 ) + COUNT()-COUNT(column4)) 其中 =;

如何将非 NULL 的列计入相同的 table？

How to COUNT Column not NULL into same table?

mysql

count

multiple-columns