mysql 日常使用语句记录

更新数据 

$sql = "UPDATE `la_goods` set `view`=`view`+1 where `id`={$goods['id']} and `status`=1";

注册的时候检查是否存在 查重

$sql = "SELECT COUNT(`id`) AS total FROM  `{$tabName}` WHERE  `username` =  '{$username}'";
    $obj = mysqli_query($con,$sql);
    $result = mysqli_fetch_assoc($obj);

    if (isset($result['total']) && "1" === $result['total']) {
        mysqli_close($con);
        msg(2, '用户名已经存在，请重新输入');
    }

删除操作

$sql = "DELETE FROM `la_goods` WHERE  id={$goodsId} AND user_id={$user['id']} LIMIT 1";

插入操作

$sql = "INSERT `la_goods`(`name`,`price`,`cid`,`content`,`pay_content`,`pay_dir`,`pic`,`user_id`,`create_time`,`update_time`,`view`,`status`) values('{$name}',{$price},'{$cid}','{$content}','{$pay_content}','{$pay_dir}','{$pic}',{$userId},{$now},{$now},{$viewTime},{$status});";

插入字段

$tabName = 'la_goods';
    $sql = "alter table `{$tabName}` add `invalid` INT(2) NOT NULL default -1 COMMENT '-1未失效。 1 失效'";
    if (!$obj = mysqli_query($con, $sql)) {
        die(mysqli_query($con) . $sql);
    }