软件开发培训班 >> 编程开发 >> SQL


SQL学习笔记六 union联合结果集使用

　　本文标签：union,联合结果集

联合结果集
新建临时工数据表
复制代码 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
复制代码 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
复制代码 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
复制代码 代码如下:

select FName from T_Employee
union all
select FName from T_TempEmployee