mysql - How to deal with several columns linking the same entity -

-

this example schema database. have following table called recipes:

id | author_name | recipe1_id | recipe2_id | recipe3_id

all recipes relations recipes_ingredients table:

id | recipe_id | ingredient1 | ingredient2 | ingredient3

right 3 joins on recipe1_id recipe3_id this:

select recipe1.ingredient1 recipe1ingredient1, recipe1.ingredient2 recipe1ingredient2, recipe1.ingredient3 recipe1ingredient3, [...] recipes inner join recipe recipe1 on (recipes.recipe1_id = recipes.id) inner join recipe recipe2 on (recipes.recipe2_id = recipes.id) inner join recipe recipe3 on (recipes.recipe3_id = recipes.id)

to map 3 recipes 1 bean in mybatis, have 3 resultsmaps map each recipe recipe object (recipe1, recipe2, recipe3) containing 3 ingredients.

but: want have recipes in list. how achieve that?

ps: sure, have 3 entities in table recipes , table recipes_ingredients. never change, don't see reason have in n:m table.

i think work.

<resultmap id="recipe1" type="recipe1">  ... </resultmap>  <resultmap id="recipe2" type="recipe2">  ... </resultmap>  <resultmap id="recipe3" type="recipe3">  ... </resultmap>  <select id="getrecipes" parametertype="list" resultmap="recipe1, recipe2, recipe3">    select recipe1.ingredient1 recipe1ingredient1, recipe1.ingredient2 recipe1ingredient2, recipe1.ingredient3 recipe1ingredient3, [...]    recipes    inner join recipe recipe1 on (recipes.recipe1_id = recipes.id)    inner join recipe recipe2 on (recipes.recipe2_id = recipes.id)    inner join recipe recipe3 on (recipes.recipe3_id = recipes.id) </select>

source: mybatis multiple resultsets


Comments

Post a Comment

Popular posts from this blog

java - Custom OutputStreamAppender not run: LOGBACK: No context given for <MYAPPENDER> -

-
i wish write custom appender on basis of outputstreamappender . wrote following class package tests; import java.io.ioexception; import java.io.outputstream; import ch.qos.logback.core.outputstreamappender; public class myappender<e> extends outputstreamappender<e> { public myappender() { system.out.println("myappender created"); setoutputstream(new outputstream() { @override public void write(int b) throws ioexception { throw new unsupportedoperationexception(); } }); } } then wrote following runner: package tests; import org.slf4j.loggerfactory; import ch.qos.logback.classic.logger; public class runner { private static final logger log = (logger) loggerfactory.getlogger(runner.class); public static void main(string[] args) { //log.addappender(new myappender<iloggingevent>()); log.info("hello world"); } } finall...
Read more

java - UML - How would you draw a try catch in a sequence diagram? -

-
Image
is there standard way of drawing try catch sequence diagrams? i've made attempt based on this feel end result doesn't feel right. code diagram based around: public static void save () { try { filehandle filehandle = gdx.files.external(file); filehandle.writestring(boolean.tostring(constantshandler.soundenabled)+"\n", false); (int = 0; < 5; i++) { filehandle.writestring(integer.tostring(constantshandler.highscores[i])+"\n", true); } } catch (throwable e) { } } my attempt note: know still need add loop. that's ok. fragments meant show conditional control flow in sequence diagram. superstructures puts limitations on use of fragments (see pp. 467 of ss2.1.1). should use critical region try part above. , option catch . however, keep telling can take quite freedom in using uml. it's language , such changes in life time. long reader ge...
Read more

c++ - No viable overloaded operator for references a map -

-
i trying use map can make tag names reference number. when try , use it, in code error (6 in total every time reference map): src/main.cpp:25:45: error: no viable overloaded operator[] type 'std::map<std::string, std::string>' const char* idcs = node.child_value(tagmap[3]); this code: #include "pugi/pugixml.hpp" #include <iostream> #include <string> #include <map> int main() { pugi::xml_document doca, docb; std::map<std::string, pugi::xml_node> mapa, mapb; std::map<std::string, std::string> tagmap {{"1", "data"}, {"2", "entry"}, {"3", "id"}, {"4", "content"}}; if (!doca.load_file("a.xml") || !docb.load_file("b.xml")) { std::cout << "can't find input files"; return 1; } (auto& node: doca.child(tagmap[1]).children(tagmap[2])) { co...
Read more