indexing

问题 Alright, PHP is throwing this error (in the log) and it's quite detrimental to the application. PHP Notice: Undefined index: sessid in methods.php on line 7 Yes, I'm aware of what this error means, what I cannot figure out is why it's obviously defined and saying it's undefined. Here is the relevant code in methods.php $sessid = mysql_real_escape_string($_REQUEST['sessid']); Now before you go off and say that "NO IT'S UNDEFINED!!!", here is the POST request to the methods.php (and yes, I'm

问题 I have 2 MySQL tables with the following schemas for a web site that's kinda like a magazine. Article (articleId int auto increment , title varchar(100), titleHash guid -- a hash of the title articleText varchar(4000) userId int) User (userId int autoincrement userName varchar(30) email etc...) The most important query is; select title,articleText,userName,email from Article inner join user on article.userId = user.UserId where titleHash = <some hash> I am thinking of using the articleId and

问题 I have a query joining lots of fields. For some strange reason the index for one table is not being used at all( I use the index key clearly), instead it is doing a FULL table scan. I would like to force the index. We used to do optimizer hints in sybase. Is there a similar hint available in oracle? For example, in sybase to join tables a, b, c and use myindex in table a, I would do : SELECT a.* FROM a(INDEX myindex), b, c WHERE a.field1 = b.field1 AND b.field1 = c.field1 Question is how do I

问题 I have a query joining lots of fields. For some strange reason the index for one table is not being used at all( I use the index key clearly), instead it is doing a FULL table scan. I would like to force the index. We used to do optimizer hints in sybase. Is there a similar hint available in oracle? For example, in sybase to join tables a, b, c and use myindex in table a, I would do : SELECT a.* FROM a(INDEX myindex), b, c WHERE a.field1 = b.field1 AND b.field1 = c.field1 Question is how do I

问题 I have a varchar(50) field named token. When I do count(distinct token) from table I get ~ 400k. However, if I do create index idx on table (token) The cardinality is only 200. What could be going on here? Shouldn't cardinality be the same as the number of distinct tokens? 回答1: The cardinality is an estimate of the number of unique values in the index. According to the documentation: Cardinality is counted based on statistics stored as integers, so the value is not necessarily exact even for

问题 I have a SQL 2005 database I've inherited, with a table that has grown to about 17 million records over the course of about 15 years, and is now horribly slow. The table layout looks about like this: id_column = nvarchar(20),indexed, not unique column2 = nvarchar(20), indexed, not unique column3 = nvarchar(10), indexed, not unique column4 = nvarchar(10), indexed, not unique column5 = numeric(8,0), indexed, not unique column6 = numeric(8,0), indexed, not unique column7 = nvarchar(20), indexed,

问题 I have a SQL 2005 database I've inherited, with a table that has grown to about 17 million records over the course of about 15 years, and is now horribly slow. The table layout looks about like this: id_column = nvarchar(20),indexed, not unique column2 = nvarchar(20), indexed, not unique column3 = nvarchar(10), indexed, not unique column4 = nvarchar(10), indexed, not unique column5 = numeric(8,0), indexed, not unique column6 = numeric(8,0), indexed, not unique column7 = nvarchar(20), indexed,

问题 i'm a little bit new for php so maybe this question is stupid. say i have a form: <form id="createNewGallery" name="newgallery" method="GET" action="code.php"><p><strong>please choose the number of pictures you want to upload: </strong> <select name="numOfPictures" id="numOfPictures"> <option>3</option> <option>4</option> <option>5</option> <option>6</option> <option>7</option> <option>8</option> <option>9</option> <option>10</option> </select></p> <input name="submitNumOfPictures" type=

问题 This question already has an answer here : Python: Object does not support indexing (1 answer) Closed 3 years ago . Using github3.py, I want to retrieve the last comment in the list of comments associated with a pull request and then search it for a string. I've tried the code below, but I get the error TypeError: 'GitHubIterator' object does not support indexing (without indexing, I can retrieve the list of comments). for comments in list(GitAuth.repo.issue(prs.number).comments()[-1]): if

问题 I have the following 2 mysql_queries : Query 1 (this query is repeated twice more for imgClass , and imgGender ): $imgFamily_query = "SELECT DISTINCT imgFamily FROM primary_images WHERE '$clause' "; Query 2: $query_pag_data = "SELECT imgId, imgURL, imgTitle, view, secondary FROM primary_images WHERE '$clause' ORDER BY imgDate DESC"; As you can see, the WHERE is controlled by a variable. This variable is calculated as follows: $where_clauses = array(); if ($imgFamilyFalse && $imgClassFalse &&