错误与正则表达式SELECT CASE

Question

我写在T-SQL下面的查询的SQL Server

SELECT 
    CASE 
     WHEN ADDR_LINE_1 REGEXP '^[0-9]' 
     THEN SUBSTRING(ADDR_LINE_1,1,CHARINDEX(' ',ADDR_LINE_1)) 
     ELSE NULL 
    END AS HOUSE_NUMBER 
FROM CUSTOMER 

我想的是，如果该列ADDR_LINE_1以数字开头，我想提取从HOUSE_NUMBER它。但现在我的查询给出了一个解析错误。如果我用LIKE替换REGEXP这个词，解析错误消失，但我总是为HOUSE_NUMBER获得NULL。我的查询的正确语法是什么？

Answer 1

你可以使用ISNUMERIC和LEFT这个样子。

SELECT 
    CASE WHEN ISNUMERIC(LEFT(ADDR_LINE_1, 1)) = 1 
    THEN SUBSTRING(ADDR_LINE_1, 1, CHARINDEX(' ', ADDR_LINE_1)) 
    ELSE NULL 
    END AS HOUSE_NUMBER 
FROM CUSTOMER 

Answer 2

如何使用LIKE

SELECT 
    CASE 
     WHEN ADDR_LINE_1 Like '%[0-9]%' 
     THEN SUBSTRING(ADDR_LINE_1,1,CHARINDEX(' ',ADDR_LINE_1)) 
     ELSE NULL 
    END AS HOUSE_NUMBER 
FROM CUSTOMER