select gid,goodsName,price,imgUrl from goods where gselect like '%"+key+"%' and state = '1' order by gid desc

这是一条SQL语句，用于从名为"goods"的数据库表中查询符合条件的记录。具体来说，它会查询表中的gid、goodsName、price和imgUrl四个字段，其中gselect字段中包含有变量key的字符串，并且state字段的值为1。结果按gid字段降序排列。这个SQL语句通常用于实现基于关键字搜索的商品查询功能，其中key变量代表用户输入的搜索关键字。

相关问题

String mid = member.get("id").toString(); // 检查该人的购物车是否有该物品 ArrayList<HashMap> cklist = (ArrayList<HashMap>) dao .select("select * from car where mid='" + mid + "' and gid='" + gid + "'"); if (cklist.size() > 0) { dao.commOper("update car set sl=sl+" + sl + " where mid='" + mid + "' and gid='" + gid + "' "); } else { dao.commOper("insert into car (gid,sl,mid) values ('" + gid + "','" + sl + "','" + mid + "')"); } out.print("true"); //登录时返回

这段代码的作用是将指定的服装加入购物车。其中，member 表示当前登录的用户的信息，包括 id 等属性。mid 表示当前登录用户的 id。首先，通过执行 SQL 语句查询该用户购物车中是否已经有该物品，如果已经有，则更新该物品数量；否则，添加新的购物车记录。最后，返回 "true"，表示加入购物车成功。如果用户未登录，则返回 "false"。该部分代码中使用的 dao 对象是一个自定义的 DAO 对象，用于执行 SQL 语句操作数据库。

SELECT t1.gname,t1.tid,t1.gid, t1.score, t1.pics FROM game t1 INNER JOIN ( SELECT tid, MAX(score) AS max_score FROM game WHERE score != '评分过少' GROUP BY tid ) t2 ON t1.tid = t2.tid AND t1.score = t2.max_score INNER JOIN gameType t3 ON t1.tid = t3.tid WHERE t3.tname IN ( SELECT tname FROM user u INNER JOIN stock s ON u.uid = s.uid INNER JOIN game g ON s.gid = g.gid INNER JOIN gameType t ON g.tid = t.tid WHERE u.uid = (SELECT uid FROM user WHERE uname = 'admin') GROUP BY tname ) ORDER BY t1.gid;优化以上sql使其相同的tid只取一条

以下是优化后的 SQL 查询语句：

SELECT t1.gname, t1.tid, t1.gid, t1.score, t1.pics
FROM (
    SELECT gname, tid, gid, score, pics,
        ROW_NUMBER() OVER (PARTITION BY tid ORDER BY gid) AS rn
    FROM game
    WHERE score != '评分过少'
) t1
INNER JOIN (
    SELECT tid, MAX(score) AS max_score
    FROM game
    WHERE score != '评分过少'
    GROUP BY tid
) t2 ON t1.tid = t2.tid AND t1.score = t2.max_score
INNER JOIN gameType t3 ON t1.tid = t3.tid
WHERE t3.tname IN (
    SELECT tname
    FROM `user` u
    INNER JOIN stock s ON u.uid = s.uid
    INNER JOIN game g ON s.gid = g.gid
    INNER JOIN gameType t ON g.tid = t.tid
    WHERE u.uid = (SELECT uid FROM `user` WHERE uname = 'admin')
    GROUP BY tname
)
AND t1.rn = 1
ORDER BY t1.gid;

在优化后的查询语句中，我使用了 ROW_NUMBER() 函数来为每个 tid 分配一个行号，然后在主查询中添加条件 t1.rn = 1 来确保只选择每个 tid 的第一条数据。这样可以实现相同的 tid 只取一条的要求。