想要比较SQL Server中的字母数字值

Question

我想比较sql server数据库中的字母数字值并选择特定范围内的值。

例如：员工等级在A1到A20的范围内，我想选择所有大于A5等级的员工。

EMP_ID     GRADE 
1111       A01
2222       A15
3333       A09
4444       A09
5555       UC
6666       A14
7777       A15
8888       TRN
9999       A04
4242       A14
1212       TRN
1515       A12
5541       UC
5563       A05


These are sample values. When I run the select query without using 
predicate "AND LEFT(GRADE,1) = 'A' ", it is only retrieving values up 
to A6,   where as it should retrieve up to A15 which is maximum in current scenario.  

Where as after using the predicate  "AND LEFT(GRADE,1) = 'A' " I am getting  
correct values i.e. up to A15 in this same scenario.  

GRADE column can have any number of repeated entries. All of them needs to be   retrieved.  
Can you please tell best possible to do this without using predicate  
"AND LEFT(GRADE,1) = 'A' "?  
 

Answer 1

您可以提取整数部分并将其用作过滤器：

SELECT * FROM TBL_NAME 
WHERE CAST(SUBSTRING(GRADE,2,LEN(GRADE)-1) AS INT) > 5