How to optimize query when join on varchar column in Sql Server -

-

i have 2 tables , b

select      a.id, b.name       inner join      b on a.name = b.name

how optimize query? name column varchar(8)

you should create index on both tables , b

create index index_name on table_name (column_name)

http://www.w3schools.com/sql/sql_create_index.asp


Comments

Post a Comment

Popular posts from this blog

php - Zend Framework / Skeleton-Application / Composer install issue -

-
i trying create zend framework application using skeleton in netbeans. when run composer install, following error message: "c:\php\php.exe" "c:\composer\composer.phar" "--ansi" "--no-interaction" "update" "--dev" using deprecated option "dev". dev packages installed default now. loading composer repositories package information updating dependencies (including require-dev) requirements not resolved installable set of packages. problem 1 - package requires php >=5.5 php version (5.4.42) not satisfy requirement. problem 2 - installation request zendframework/zendframework 2.5.1 -> satisfiable zendframework/zendframework[2.5.1]. - zendframework/zendframework 2.5.1 requires php >=5.5 -> php version (5.4.42) not satisfy requirement. done. apparently, zend framework only needs php 5.3+ contradicts above. need use php 5.4. my composer.json following: { "name": "
Read more

c# - Better 64-bit byte array hash -

-
i need hash algorithm produces 64-bit hash code ( long ) fewer collisions string.gethashcode() , fast (no expensive calls cryptographic functions). here's implementation of fnv still shows 3% of collisions after testing 2 million random strings. need number way lower. void main() { const string chars = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz!#@$%^&*()_+}{\":?><,./;'[]0123456789\\"; const int n = 2000000; var random = new random(); var hashes = new hashset<long>(); int collisions = 0; for(int = 0; < n; i++) { var len = random.next(chars.length); var str = new char[len]; (int j = 0; j < len; j++) { str[j] = chars[random.next(chars.length)]; } var s = new string(str); if(!hashes.add(get64bithash( s ))) collisions++; } console.writeline("collision percentage after " + n + " random strings: " + ((doubl
Read more

python - PyCharm Type error Message -

-
i'm newbie trying out ml/dbn in python (3.4) under pycharm (comm.ed 4.5). following definition def make_thetas(xmin,xmax,n): xs = np.linespace(xmin,xmax,n) widths = (xs[1:] - xs[:-1])/2.0 thetas = xs[:-1] + widths return thetas throws error "class 'tuple' not define ' sub ', '-' operator cannot used on instance" on - operator on third line (widths = ....) ideas on how code running under pycharm - works alright in interactive python window. thx. to all, after g'g lot have found workaround seems work within pycharm. workaround because (even python newbie) expected python not need explicit typecasting, not when using datatypes imported lib such numpy. def make_thetas(xmin,xmax,n): xs = np.array(np.linspace(xmin,xmax,n)) widths = (xs[1:] - xs[:-1])/2.0 thetas = xs[:-1]+ widths return thetas using docstrings type-hinting such below did not work def make_thetas(xmin,xmax,n): "&q
Read more