mysql：查找具有多个标签和相同id的行

问题的类型称为

Relational Division

SELECt  a.md5,         a.url,        a.titleFROM    links a        INNER JOIN Tags b ON a.md5 = b.md5WHERe   b.Tag IN ('awesome', 'useful') -- <<== list of desired tagsGROUP   BY a.md5, a.url, a.titleHAVINg  COUNT(*) = 2        -- <<== number of tags defined

• SQLFiddle演示
• 关系部门的SQL

输出

╔══════╦════════════╦═══════╗║ MD5  ║    URL     ║ TITLE ║╠══════╬════════════╬═══════╣║ a0a0 ║ google.com ║ foo   ║