在MySQL中添加一个带有值的临时列？
您可以借助以下语法添加具有值的临时列-
select yourColumnName1,yourColumnName2,.....N ,yourTemporaryColumnValue as yourTemporaryColumnName from yourTableName;
要添加一个带有值的临时列，让我们创建一个表。以下是查询-
mysql> create table TemporaryColumnWithValueDemo
−> (
−> StudentId int,
−> StudentName varchar(100)
−> );在表中插入一些记录。插入记录的查询如下-
mysql> insert into TemporaryColumnWithValueDemo values(101,'John'); mysql> insert into TemporaryColumnWithValueDemo values(102,'Johnson'); mysql> insert into TemporaryColumnWithValueDemo values(103,'Carol'); mysql> insert into TemporaryColumnWithValueDemo values(104,'Sam');
显示上面插入的所有记录。显示所有记录的查询如下-
mysql> select *from TemporaryColumnWithValueDemo;
以下是输出-
+-----------+-------------+ | StudentId | StudentName | +-----------+-------------+ | 101 | John | | 102 | Johnson | | 103 | Carol | | 104 | Sam | +-----------+-------------+ 4 rows in set (0.00 sec)
现在，这里是添加带有t.emporary值的列的查询。查询如下-
mysql> select StudentId,StudentName,'M.I.T.' as TempCollegeName from TemporaryColumnWithValueDemo;
以下是输出。临时列已成功添加-
+-----------+-------------+-----------------+ | StudentId | StudentName | TempCollegeName | +-----------+-------------+-----------------+ | 101 | John | M.I.T. | | 102 | Johnson | M.I.T. | | 103 | Carol | M.I.T. | | 104 | Sam | M.I.T. | +-----------+-------------+-----------------+ 4 rows in set (0.00 sec)