列连接返回“Null”Mysql - Php
问题描述：
I can able to concatenate the values using the following code
$sqlselect = "UPDATE billing_details SET SRF = CONCAT(Year, ID)";
but it returns the result value as "NULL". Kindly help me to solve this issue
Table Structure:
Year *Varchar(5)*
ID *Int(10)*
SRF *Varchar(100)*
Result Table:
Year Id SRF
A 1 NULL
A 2 NULL
A 3 NULL
我可以使用以下代码连接值 p>
$ sqlselect =“UPDATE billing_details SET SRF = CONCAT（Year，ID）”;
code> pre>
但它返回结果值为“NULL”。 请帮我解决这个问题 p>
表格结构： strong> p>
Year * Varchar（5）* \ n
ID * Int（10）*
SRF * Varchar（100）*
code> pre>
结果表： p>
年份Id SRF h2>
A 1 NULL h2>
A 2 NULL h2>
A 3 NULL h2> \ n div>
答
MySql CONCAT function is return NULL if any argument value if null value, see blow
SELECT COCAT(NULL, 1)
OR
SELECT COCAT(1, NULL)
>NULL
If you want to keep other values while any argument value have null then use IFNULL() function to exclude NULL values
In your query
$sqlselect = "UPDATE billing_details SET SRF = CONCAT(IFNULL(Year, ''), IFNULL(ID, ''))";