匿名通过本文主要向大家介绍了union,联合结果集等相关知识,希望本文的分享对您有所帮助
SQL学习笔记六 union联合结果集使用，需要的朋友可以参考下。
联合结果集新建临时工数据表
代码如下:
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联合
代码如下:
select FNumber,FAge from T_Employee
union
select FIdCardNumber,FAge from T_TempEmployee
union上下的查询个数和类型必须对应一致
代码如下:
select FNumber,FAge,FDepartment from T_Employee
union
select FIdCardNumber,FAge ,'临时工，无部门' from T_TempEmployee
union默认将重复数据去掉。如果不让他去掉，则用union all
代码如下:
select FName from T_Employee
union all
select FName from T_TempEmployee