mysql - How to add primary key in SQL? -


this question has answer here:

i created table(let's contact info), forgot create primary key. since entered values in table want keep table , want add primary key column. how add primary key column on left side of table incremental numbers?

you can add auto-incrementing column:

alter table contact_info add column id int primary key auto_increment;

Comments

Post a Comment

Popular posts from this blog

ruby - How do I merge two hashes into a hash of arrays? -

http://codepad.org/wmyzqlis i'd merge these 2 arrays: a = { :a => 'a', :b => 'b', :d => 'd' } b = { :a => '1', :b => 'b', :c => 'c' } into hash looks this: {:a => ["a", "1"], :b => ["b", "b"], :c => [nil, "c"], :d => ["d", nil] } this doesn't work: p a.merge(b) { |k, v1, v2| [v1, v2] } # {:c=>"c", :a=>["a", "1"], :b=>["b", "b"], :d=>"d"} it's because hash#merge call block duplicate keys. a = { :a => 'a', :b => 'b', :d => 'd' } b = { :a => '1', :b => 'b', :c => 'c' } hash[(a.keys|b.keys).map { |key| [key, [a.fetch(key, nil), b.fetch(key, nil)]] }] # => {:a=>["a", "1"], :b=>["b", "b"], :d=>["d", nil], :c=>...
Read more

java - the value of local variable is not used -

this question has answer here: java error “value of local variable not used” 7 answers i wrote small program check given movie name exist in folder. getting warning on eclipse "the value of local variable not used" here main method public static void main(string[] args) { // todo auto-generated method stub boolean movie_exist=false; system.out.println("hellow world!"); try{ filewriting newfolrder = new filewriting("h:\\breakinbad2\\breaking bad season 2 complete 720p.brrip.sujaidr"); //movie_exist=newfolrder.checkfilesname("movie name"); system.out.println(newfolrder.checkmovieexist("breaking bad")); movie_exist = newfolrder.checkmovieexist("breaking bad"); }catch(nullpointerexception e){ system.out.println("exce...
Read more