Mysql 如何从.NET上的varchar获取下一个相关id?
我在MySQL数据库上有这样一个代码:Mysql 如何从.NET上的varchar获取下一个相关id?,mysql,.net,Mysql,.net,我在MySQL数据库上有这样一个代码: MD-54564 MD-54565 MD-54566 string code_select = "SELECT MAX(CAST((SUBSTRING(code,4)) as UNSIGNED)) FROM table WHERE code like 'MD-%'"; DataTable code = new DataTable(); code = conexion.mySelect(code_select); num_code = Int32.Pa
MD-54564
MD-54565
MD-54566
string code_select = "SELECT MAX(CAST((SUBSTRING(code,4)) as UNSIGNED)) FROM table WHERE code like 'MD-%'";
DataTable code = new DataTable();
code = conexion.mySelect(code_select);
num_code = Int32.Parse(code);
num_code = num_code + 1;
code= "MD-" + num_code.ToString();
因此,我需要获得下一个代码,并尝试以下内容:
MD-54564
MD-54565
MD-54566
string code_select = "SELECT MAX(CAST((SUBSTRING(code,4)) as UNSIGNED)) FROM table WHERE code like 'MD-%'";
DataTable code = new DataTable();
code = conexion.mySelect(code_select);
num_code = Int32.Parse(code);
num_code = num_code + 1;
code= "MD-" + num_code.ToString();
这给了我第四行的
CS1502错误。你能在code
周围添加`来转义这个词吗,因为它是MySQL中的一个
以下代码正在运行:
SELECT MAX(CAST((SUBSTRING(`code`, 4)) AS UNSIGNED))
FROM table
WHERE `code` LIKE 'MD-%';
检查演示:谢谢,这样更好。如何将DataTable结果转换为字符串?明白了。谢谢