SQL學習筆記六 union聯合結果集使用

聯合結果集
新建臨時工數據表
復制代碼 代碼如下:
CREATE TABLE T_TempEmployee (FIdCardNumber VARCHAR(20),FName VARCHAR(20),FAge int,PRIMARY KEY(FIdCardNumber));
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890121','Sarani',33);
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890122','Tom',26);
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890123','Yalaha',38);
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890124','Tina',26);
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890125','Konkaya',29);
INSERT INTO T_TempEmployee(FIdCardNumber,FName,FAge) VALUES('1234567890126','Fotifa',46);


Union聯合
復制代碼 代碼如下:
select FNumber,FAge from T_Employee
union
select FIdCardNumber,FAge from T_TempEmployee


union上下的查詢個數和類型必須對應一致
復制代碼 代碼如下:
select FNumber,FAge,FDepartment from T_Employee
union
select FIdCardNumber,FAge ,'臨時工，無部門' from T_TempEmployee


union默認將重復數據去掉。如果不讓他去掉，則用union all
復制代碼 代碼如下:
select FName from T_Employee
union all
select FName from T_TempEmployee