MySQL 添加一个带有值的临时列
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add a temporary column with a value
提问by Asim Zaidi
I have a select statement like this
我有一个像这样的选择语句
select field1, field2
from table1
What I want is to have a newfield with only value "example".
我想要的是有一个只有值“example”的新字段。
newfielddoes not exist in the table, but when I run this query it kinda makes a virtual column with the values of example field.
newfield表中不存在，但是当我运行此查询时，它会创建一个包含示例字段值的虚拟列。
回答by Steve Homer
select field1, field2, 'example' as TempField
from table1
This should work across different SQL implementations.
这应该适用于不同的 SQL 实现。
回答by OMG Ponies
You mean staticly define a value, like this:
您的意思是静态定义一个值，如下所示：
SELECT field1,
field2,
'example' AS newfield
FROM TABLE1
This will add a column called "newfield" to the output, and its value will always be "example".
这将在输出中添加一个名为“newfield”的列，其值将始终为“example”。
回答by DA.
I'm rusty on SQL but I think you could use select as to make your own temporary query columns.
我对 SQL 生疏了，但我认为您可以使用 select as 来制作自己的临时查询列。
select field1, field2, 'example' as newfield from table1
That would only exist in your query results, of course. You're not actually modifying the table.
当然，那只会存在于您的查询结果中。您实际上并没有修改表格。
回答by DA.
select field1, field2, NewField = 'example' from table1
回答by Dlorko
I giving you an example in wich the TABLE registrofaena doesn't have the column called minutos. Minutos is created and it content is a result of divide demora/60, in other words, i created a column to show the values of the delay in minutes.
我给你在至极表registrofaena没有列称为一个例子minutos。Minutos 被创建，它的内容是除以 demora/60 的结果，换句话说，我创建了一个列来显示以分钟为单位的延迟值。
This is the query:
这是查询：
SELECT idfaena,fechahora,demora, demora/60 as minutos,comentario
FROM registrofaena
WHERE fecha>='2018-10-17' AND comentario <> ''
ORDER BY idfaena ASC;
This is the view:
这是视图：
回答by Raj Shekhar Singh
select field1, field2, '' as newfield from table1
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