必要なSQL構文

Question

表1

**asset_tag   assigned_to  serial    model_number**    
AST-L1516-0127    NULL  NDD513738D   HP 240     
AST-D1112-0205    1  ddafadf    HP 240     
AST-D1213-0202    NULL  L52ha13    Lenovo thinkcenter M72e 
AST-D1516-0203    2  FGBH622    Dell Optiplex 3020  
AST-L1516-0077    NULL  3835LY32   Dell LATITUDE 3450  
AST-L1415-0002    NULL  CNFGH95LZJ   HP 240G3     

および表2

id username 
1  pavan 
2  kalyan 

必要なコマンド=表2におけるID割り当てられた場合にはご利用いただけません表2にそれを追加する必要はありません

**asset_tag   assigned_to  serial    model_number    username** 
AST-L1516-0127    NULL  NDD513738D   HP 240      Not Available 
AST-D1112-0205    1  ddafadf    HP 240      pavan 
AST-D1213-0202    NULL  L52ha13    Lenovo thinkcenter M72e Not Available 
AST-D1516-0203    2  FGBH622    Dell Optiplex 3020   kalyan 
AST-L1516-0077    NULL  3835LY32   Dell LATITUDE 3450   Not Available 
AST-L1415-0002    NULL  CNFGH95LZJ   HP 240G3     Not Available 

Answer 1

使用石炭esce（）関数

select a.asset_tag, a.assigned_to,a.serial,a.model_number,coalesce(b.username,'Not Available') as username 
from table1 a left join table2 b on a.assigned_to = b.id;