Efficient String Compare To A Group Of Values
(Post edited to change "WHERE field = options" to "WHERE field IN options").
I have a website using PHP and MySQL 5.0; the database holds personal names, addresses and various information. Right now I'm building a query which checks whether a person lives in a certain group of UK counties.
I've got arrays set up in PHP which hold the groups of counties, and I've dynamically created a "group" from each array. So, in PHP,
$county_array = array('Kent','Surrey','London','Essex','...');
$county_group gets set to "('kent','surrey','london','essex',...)"
Each group may hold perhaps 20 individual counties.
Now, for my database query, I use:
$query = "SELECT ... WHERE lower(county) IN $county_group";
Is the "WHERE field IN (a|b|c|d|e|...)" a slow comparison in MySQL? Is there a more efficient way to do it? Is this something that stored procedures can help me with?
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I have searched this forum seeking the answer to this question, to no avail. I am making an events diary that will have a lot of entries. Entries will be entered in all kinds of order, including multiple events spanning a year or so. Even multiple events of the same type will be individual entries. (e.g. weekly chess club meeting every weds at 7pm will be 52 entries) My question is : Which is the best format to store dates? Native mysql date type Integer timestamp A.n.other? I suppose a worst case scenario is imagine I want to generate a calendar for July (31 days) and I want to show how many events there are for each day. 1st July (13 events) 2nd July (22 events) and so on ... it is possible that any given day could have up to 100 entries. What in your opinion is the best column type to use and ss there any kind of Indexing I can use to speed up select by dates? Or any other tip or trick you'd be prepared to share with me?
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Using UPDATE To Insert A String Into String
Is there a way/function that will insert a string into another string using UPDATE? for example: I have a 'text (string) column' where I want to add '/' after every 4 characters. hex1hex2hex3 into hex1/hex2/hex3/ I was looking at the substring command, but it can only be used with SELECT?
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Group By With Order BY, Or INSERT INTO (SELECT * GROUP BY)?
I seem to have a few duplicates entries in a very large database. My database has two identical tables. One is written to on a regular basis (every few seconds) and the other is used for queries, and updated from the write table on a daily basis. I'm trying to get rid of duplicate entries for the queries, and I thought the most effective way to do this would be to run the query as Expand|Select|Wrap|Line Numbers
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