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  • Null Value Statement

    - by Sam
    Hi All, I have created a table called table1 and it has 4 columns named Name,ID,Description and Date. I have created them like Name varchar(50) null, ID int null,Description varchar(50) null, Date datetime null I have inserted a record into the table1 having ID and Description values. So Now my table1 looks like this: Name ID Description Date Null 1 First Null One of them asked me to modify the table such a way that The columns Name and Date should have Null values instead of Text Null. I don't know what is the difference between those I mean can anyone explain me the difference between these select statements: SELECT * FROM TABLE1 WHERE NAME IS NULL SELECT * FROM TABLE1 WHERE NAME = 'NULL' SELECT * FROM TABLE1 WHERE NAME = ' ' Can anyone explain me?

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  • Any way to avoid a filesort when order by is different to where clause?

    - by Julian
    I have an incredibly simple query (table type InnoDb) and EXPLAIN says that MySQL must do an extra pass to find out how to retrieve the rows in sorted order. SELECT * FROM `comments` WHERE (commentable_id = 1976) ORDER BY created_at desc LIMIT 0, 5 exact explain output: table select_type type extra possible_keys key key length ref rows comments simple ref using where; using filesort common_lookups common_lookups 5 const 89 commentable_id is indexed. Comments has nothing trick in it, just a content field. The manual suggests that if the order by is different to the where, there is no way filesort can be avoided. http://dev.mysql.com/doc/refman/5.0/en/order-by-optimization.html I also tried order by id as well as it's equivalent but makes no difference, even if I add id as an index (which I understand is not required as id is indexed implicitly in MySQL). thanks in advance for any ideas!

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  • Select rows in random order and then reverse it

    - by Faruz
    I need to select rows in random order and return a query which holds the rows in both regular order and in reverse order. This is done to simulate a fantasy draft for a basketball game I'm working on. For example, I need a result set as followed: team1 1 team2 2 team6 3 team9 4 team9 5 team6 6 team2 7 team1 8 As you can see, the first four teams are random then then following four are in reverse order. Hope I managed to explain the problem, if not - please comment and I'll explain further.

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  • Replacing the Import Table in PE file by standart LoadLibrary...

    - by user308368
    Hello. I have an executable (PE) file that load a dll file as represented in the Import table... let say: PEFile.exe Modules.dll my question is how can i remove Modules.dll's import_descriptor from the imports and do its work by loadLibrary without the rely on the import table and without destroy the file???... My bigger problem his i could not understand exactly how the Import thing works... after the loader read the information he needs to do the import's thing, i believe he use the LoadLibrary, GetProcAddress APIs... but i couldn't understated what he doing with the pointers he get... he putting them somewhere in memory... and then what just call them?!? all the papers i found in the net explain the structure of the import table, but i didn't found a paper that explain how it is really work and get used... i hope you cold understand my Gibberish English... Thank you!

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  • Reaplaceing the Import Table in PE file by standart LoadLibrary...

    - by user308368
    Hello. I have an executable (PE) file that load a dll file as represented in the Import table... let say: PEFile.exe Modules.dll my question is how can i remove Modules.dll's import_descriptor from the imports and do its work by loadLibrary without the rely on the import table and without destroy the file???... My bigger problem his i could not understand exactly how the Import thing works... after the loader read the information he needs to do the import's thing, i believe he use the LoadLibrary, GetProcAddress APIs... but i couldn't understated what he doing with the pointers he get... he putting them somewhere in memory... and then what just call them?!? all the papers i found in the net explain the structure of the import table, but i didn't found a paper that explain how it is really work and get used... i hope you cold understand my Gibberish English... Thank you!

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  • How to add indexes to MySQL tables?

    - by Michael
    I've got a very large MySQL table with about 150,000 rows of data. Currently, when I try and run SELECT * FROM table WHERE id = '1'; the code runs fine as the ID field is the primary index. However, recently for a development in the project, I have to search the database by another field. For example SELECT * FROM table WHERE product_id = '1'; This field was not previously indexed, however, I've added it as an index but when I try to run the above query, the results is very slow. An EXPLAIN query reveals that there is no index for the product_id field when I've already added one and as a result the query takes any where from 20 minutes to 30 minutes to return a single row. EDIT: My full EXPLAIN results are: | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+----------------------+------+---------+------+------+------------------+ | 1 | SIMPLE | table | ALL | NULL | NULL | NULL | NULL | 157211 | Using where | +----+-------------+-------+------+----------------------+------+---------+------+------+------------------+

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  • Are the atomic builtins provided by gcc actually translated into the example code, or is that just f

    - by Jared P
    So I was reading http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html, and came across this: type __sync_and_and_fetch (type *ptr, type value, ...) type __sync_xor_and_fetch (type *ptr, type value, ...) type __sync_nand_and_fetch (type *ptr, type value, ...) These builtins perform the operation suggested by the name, and return the new value. That is, { *ptr op= value; return *ptr; } { *ptr = ~*ptr & value; return *ptr; } // nand Is this code literal? or is it just to explain what gcc is doing atomically using c-like syntax? And if this is the direct translation, can someone explain how it is atomic?

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  • behavior of memset

    - by Vinicius Horta
    Does this function has the same behavior that 'memset'? (Oops! Your question couldn't be submitted because: Your post does not have much context to explain the code sections; please explain your scenario more clearly. ) inline void SetZeroArray( void *vArray[], unsigned int uArraySize ) { for(unsigned i=0; i<=uArraySize; i++ ) vArray[i] = NULL; } int main( int argc, char *argv[] ) { unsigned int uLevels[500]; SetZeroArray( (void**)uLevels, 500 ); unsigned int ulRLevels[500]; memset( &ulRLevels, 0, sizeof( ulRLevels ) ); system("pause>nul"); return EXIT_SUCCESS; }

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