条件语句

1、IF语句

select x,y,z,IF(x+y>z AND x+z>y AND y+z>x,"Yes","No") triangle from triangle

2、CASE语句

select 
    * ,
    (
    case
        when x+y>z and x+z>y and y+z>x then 'Yes'
        else 'No'
    end
    )triangle
from
    triangle

二、

update  Salary  set sex =if(sex="m","f","m")

三、Case-when-then-else-end

select 
     id
    , sum(case `month` when 'Jan' then revenue else null end) as Jan_Revenue
    , sum(case `month` when 'Feb' then revenue else null end) as Feb_Revenue
    , sum(case `month` when 'Mar' then revenue else null end) as Mar_Revenue
    , sum(case `month` when 'Apr' then revenue else null end) as Apr_Revenue
    , sum(case `month` when 'May' then revenue else null end) as May_Revenue
    , sum(case `month` when 'Jun' then revenue else null end) as Jun_Revenue
    , sum(case `month` when 'Jul' then revenue else null end) as Jul_Revenue
    , sum(case `month` when 'Aug' then revenue else null end) as Aug_Revenue
    , sum(case `month` when 'Sep' then revenue else null end) as Sep_Revenue
    , sum(case `month` when 'Oct' then revenue else null end) as Oct_Revenue
    , sum(case `month` when 'Nov' then revenue else null end) as Nov_Revenue
    , sum(case `month` when 'Dec' then revenue else null end) as Dec_Revenue
from Department group by id