mySQL 查询:如何使用 UNION 插入?

问题描述

我对 mySQL:s union 函数有点陌生，至少在对它们进行插入时是这样.根据网上找到的一个例子，我得到了以下工作:

I am kind of new to mySQL:s union functions, at least when doing inserts with them. I have gotten the following to work based upon a example found on the net:

INSERT INTO tableOne(a, b)
SELECT a, $var FROM tableOne
WHERE b = $var2
UNION ALL SELECT $var,$var

好的，这没什么奇怪的.但是当我想在数据库中插入第三个与 Select 的逻辑无关的值时会发生什么?

Ok, nothing strange about that. But what happens when I want to insert a third value into the database that has nothing to do with the logic of the Select being done?

喜欢:INSERT INTO tableOne(a, b, c)

这怎么可能?

推荐答案

您也可以选择"字面值:

You can "select" literal values too:

mysql> select 'hello', 1;
+-------+---+
| hello | 1 |
+-------+---+
| hello | 1 |
+-------+---+
1 row in set (0.00 sec)

因此，您也可以在 INSERT INTO ... SELECT FROM 和 UNION 中使用它.

Hence, you can also use that in INSERT INTO ... SELECT FROM and UNIONs.

INSERT INTO someTable (a, b, c) VALUES
SELECT id, name, 5
FROM someOtherTable
UNION
SELECT id, alias, 8
FROM anotherTable

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