如果第一个值不为空，则用另一个值替换一个值

Question

我有以下情况（请运行虚拟数据集），其中 FS_Number 有真实的 FS_Numbers，NULL 和随机文本，例如 N/A_ADMINIS2 这需要用 FS_Number1

中的值替换

SELECT 1 AS ID, 214565 AS FS_Number1, Null AS  FS_Number
UNION
SELECT 2 AS ID, null   AS FS_Number1, '759843' AS  FS_Number
UNION
SELECT 3 AS  ID, null   AS FS_Number1, '243545' AS  FS_Number
UNION
SELECT 4 AS ID, null   AS FS_Number1, '655342' AS  FS_Number
UNION
SELECT 5 AS ID, 897324 AS FS_Number1, 'N/A_ADMINIS2' AS  FS_Number
UNION
SELECT 6 AS  ID, 934895 AS FS_Number1, 'N/A_ADMINIS2' AS  FS_Number
UNION
SELECT 7 AS ID, 3453 AS FS_Number1, Null AS  FS_Number
UNION
SELECT 8 AS ID, 85634542 AS FS_Number1, 'N/A_3' AS  FS_Number
UNION
SELECT 9 AS  ID, 3451124 AS FS_Number1, 'N/A_1' AS  FS_Number

看起来像这样：

ID  FS_Number1  FS_Number
1   214565      NULL
2   NULL        759843
3   NULL        243545
4   NULL        655342
5   897324      N/A_ADMINIS2
6   934895      N/A_ADMINIS2
7   3453        NULL
8   85634542    N/A_3
9   3451124     N/A_1

结果应如下所示：

SELECT 1 AS ID, 214565 AS FS_Number1, '214565' AS  FS_Number
UNION
SELECT 2 AS ID, null   AS FS_Number1, '759843' AS  FS_Number
UNION
SELECT 3 AS  ID, null   AS FS_Number1, '243545' AS  FS_Number
UNION
SELECT 4 AS ID, null   AS FS_Number1, '655342' AS  FS_Number
UNION
SELECT 5 AS ID, 897324 AS FS_Number1, '897324' AS  FS_Number
UNION
SELECT 6 AS  ID, 934895 AS FS_Number1, '934895' AS  FS_Number
UNION
SELECT 7 AS ID, 3453 AS FS_Number1, '3453' AS  FS_Number
UNION
SELECT 8 AS ID, 85634542 AS FS_Number1, '85634542' AS  FS_Number
UNION
SELECT 9 AS  ID, 3451124 AS FS_Number1, '3451124' AS  FS_Number

看起来像这样：

ID  FS_Number1  FS_Number
1   214565      214565
2   NULL        759843
3   NULL        243545
4   NULL        655342
5   897324      897324
6   934895      934895
7   3453        3453
8   85634542    85634542
9   3451124     3451124

我知道您可以用 COALESCE 替换 NULL 值，但就我而言，我还有需要用数字替换的文本。最好的方法是什么？

Answer 1

你可以用 try_convert():

select id, fs_number1,
    case when try_convert(int, fs_number) is null
        then fs_number1
        else fs_number
    end as fs_number
from mytable

想法是尝试将值转换为数字。如果转换尝试 returns null，则意味着该字符串不是数字，或者是 null：在这种情况下，我们使用替代值。

Demo on DB Fiddle:

id | fs_number1 | fs_number
-: | ---------: | --------:
 1 |     214565 |    214565
 2 |       null |    759843
 3 |       null |    243545
 4 |       null |    655342
 5 |     897324 |    897324
 6 |     934895 |    934895
 7 |       3453 |      3453
 8 |   85634542 |  85634542
 9 |    3451124 |   3451124

Answer 2

这类似于 GMB 的版本，但使用合并而不是大小写。

select id, fs_number1,
    coalesce(try_convert(int, fs_number), fs_number1) as fs_number
from mytable

如果第一个值不为空，则用另一个值替换一个值

Replace a value with another value if that first value is not null

sql

tsql

sql-server

select

sql-null