INSERT FIRST介紹

何謂INSERT FIRST

• INSERT FIRST要搭配WHEN......THEN語句使用,判對第一個WHEN語句條件如果為TRUE就插入資料列,而其後的WHEN語句就省略判斷,如果為FIRST就往下列WHEN語句判斷,以此類推,它跟INSERT ALL一樣在多表格插入資料列

格式

INSERT FIRST

          WHEN condition THEN insert_into_clause [insert_into_clause...]

          [WHEN condition THEN insert_into_clause [insert_into_clause...]...]

          [ELSE insert_into_clause [insert_into_clause...]]

          (subquery);

使用方式

• SQL語法示範

如果salary大於4000新增到emp2表格,如果第一個WHEN條件就為TRUE,而其後的WHEN語句就省略判斷,以此類推

insert first

     when salary>4000 then into emp2

     when salary>5000 then into emp3

     when salary>6000 then into emp4

select salary from employees;