Mysql &引用；“分类”；或；标记“；选择查询

我有一个从多个数据库中选择列“auth”=mad的查询：

$result = mysql_query("SELECT * FROM test.1 WHERE auth = 'mad' LIMIT 1 
    UNION SELECT * FROM test.2 WHERE auth = 'mad' LIMIT 1 
    UNION SELECT * FROM test.3 WHERE auth = 'mad' LIMIT 1");

我如何标记或分类测试结果。1；测试2还是测试3

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非常感谢。

将表名添加到结果中：

$result = mysql_query("SELECT *, 'test.1' FROM test.1 WHERE auth = 'mad' LIMIT 1 
                  UNION SELECT *, 'test.2' FROM test.2 WHERE auth = 'mad' LIMIT 1 
                  UNION SELECT *, 'test.3' FROM test.3 WHERE auth = 'mad' LIMIT 1");

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如果我理解正确，您只需添加一列。此外，最好使用

union all

而不是

union

，因为

union

也会花费额外的精力来消除重复项：

SELECT 1 as test, t1.* FROM test.1 t1 WHERE auth = 'mad' LIMIT 1 
    UNION ALL
SELECT 2 as test, t2.* FROM test.2 t2 WHERE auth = 'mad' LIMIT 1 
    UNION ALL
SELECT 3 as test, t3.* FROM test.3 t3 WHERE auth = 'mad' LIMIT 1;

SELECT 1 as test, t1.* FROM test.1 t1 WHERE auth = 'mad' LIMIT 1 
    UNION ALL
SELECT 2 as test, t2.* FROM test.2 t2 WHERE auth = 'mad' LIMIT 1 
    UNION ALL
SELECT 3 as test, t3.* FROM test.3 t3 WHERE auth = 'mad' LIMIT 1;