Type = SqlFunc.IF(s.Type == 10).Return(1) 
            .ElseIF(s.Type == 20).Return(2) 
            .End(0)

等同于Select语句中的

(CASE 
WHEN ( [s].[type] =10 ) THEN 1 
WHEN ( [s].[type] = 20 ) THEN 2 
ELSE 0 
END ) AS [Type]

SqlSugar种CASE WHEN的用户