mysql - whats wrong. when i call foreign key -

- 

create table applicant ( applicant_id varchar(10) not null, applicant_name nvarchar (25) not null, father_name nvarchar (25), gender nvarchar (15), applicant_dob datetime, qualifaction nvarchar (45), application_id varchar (15), primary key (applicant_id, applicant_name)   );   create table application ( application_id varchar (10), application_name nvarchar(25), applicant_id varchar (10), applicant_name nvarchar (25), primary key (application_id)  );   create table cell_number ( cell_no varchar (15) not null , applicant_id varchar (10), applicant_name nvarchar (25), primary key (cell_no)  );   alter table cell_number add constraint fk_applicant_id foreign key (applicant_id) references applicant (applicant_id);  alter table cell_number add constraint fk_applicant_name foreign key (applicant_name) references applicant (applicant_name);

show error

msg 1776, level 16, state 0, line 34 there no primary or candidate keys in referenced table 'applicant' match referencing column list in foreign key 'fk_applicant_id'. msg 1750, level 16, state 0, line 34 not create constraint. see previous errors.

you can't create foreign key references 1 column of primary key pair.

alter table cell_number add constraint fk_applicant    foreign key (applicant_id, applicant_name) references    applicant (applicant_id, applicant_name)

this because foreign key needs identify 1 row in applicant table, , since primary keys reference 2 columns, can't use 1 column generate foreign key.

edit: can reference 1 column of composite primary key, corrected justin


Comments

Post a Comment

Popular posts from this blog

python - Subclassed QStyledItemDelegate ignores Stylesheet -

-
i'm trying subclass qstyleditemdelegate remove focus rectangle in qcombobox . even though i'm calling base implementation of paint function , nothing else, result different. looks if parts of style-sheet influence bounding box of item taken consideration. class pstyleditemdelegate(qstyleditemdelegate): def __init__(self, *args, **kwds): super(pstyleditemdelegate, self).__init__(*args, **kwds) def paint(self, *args, **kwargs): qstyleditemdelegate.paint(*args, **kwargs) what have paint unmodified qstyleditemdelegate ? as suggested tried replacing pyside pyqt4 , works, appears bug. update pyside 1.1.2 1.2.1 result same. unfortunately switch breaks other parts of code, if there no other suggestions i'm going accept answer. edit bug tracked here
Read more

java - HttpClient 3.1 Connection pooling vs HttpClient 4.3.2 -

-
i have used httpclient3.1(java) connection pooling below : import org.apache.commons.httpclient.httpclient; import org.apache.commons.httpclient.multithreadedhttpconnectionmanager; import org.apache.commons.httpclient.params.httpclientparams; import org.apache.commons.httpclient.params.httpmethodparams; import org.apache.log4j.logger; public class httpclientmanager { private static logger logger = logger.getlogger(httpclientmanager.class); private static multithreadedhttpconnectionmanager connectionmanager = new multithreadedhttpconnectionmanager(); private static httpclientparams clientparams = new httpclientparams(); static { try { clientparams.makelenient(); clientparams.setauthenticationpreemptive(false); clientparams.setparameter(httpmethodparams.so_timeout, new integer(30000)); // set so_timeout clientparams.setparameter(httpmethodparams.head_body_check_timeout, new integer(3000)); // head responses ...
Read more

node.js - StackOverflow API not returning JSON -

-
i using node.js script gather data stackoverflow. know responses gzipped, put code in should take care of that. script follows: var request = require('request'); var zlib = require('zlib'); function getstackoverflowresponse(url, callback){ request(url, {encoding: null}, function(err, response, body){ if(response.headers['content-encoding'] == 'gzip'){ zlib.gunzip(body, function(err, dezipped) { callback(dezipped); }); } else { callback(body); } }); } var url = "https://api.stackexchange.com/docs/questions#pagesize=2&order=desc&min=2014-01-04&max=2014-02-02&sort=activity&tagged=apigee&filter=default&site=stackoverflow&run=true"; getstackoverflowresponse(url, function(questions) { console.log(questions); }); instead of getting json output, i'm getting following response: buffer 0d 0a 0d 0a 0d 0a 0d 0a 3c 21 44 4f 43 54 59 50 45 20 48...
Read more