java - Using multiple tables to get data SQLitedatabase -


i have 3 tables in database: category, words, , wordimgs. i'm trying implement listgetallcategories , problem need retrieve data 3 tables in order this. suppose join 3 tables? not quite sure how accomplish this.

each category contains name , arraylist of words. each word contains name arraylist of images.

statements used create tables:

public void oncreate(sqlitedatabase db) {     final string sql_create_category_table = "create table " + categories_table + " (" +             _id + " integer primary key autoincrement," +             title + " text not null " + ");";     final string sql_create_words_table = "create table " + words_table + " (" +             _id + " integer primary key autoincrement," +             title + " text not null, " +             belongs_to + " integer not null, " +             "foreign key (" + belongs_to + ") references " + categories_table + " (" + _id + ")" +             ");";     final string sql_create_wordimg_table = "create table " + wordimgs_table + " (" + _id + " " +             "integer primary key autoincrement," + title + " text not null, " +             belongs_to + " integer not null, " +             "foreign key (" + belongs_to + ") references " + words_table + " (" + _id + ")" +             ");";        db.execsql(sql_create_category_table);     db.execsql(sql_create_words_table);     db.execsql(sql_create_wordimg_table);  }

you can join 3 tables this:

select * categories_table c join words_table w on c.id = w.belongs_to join wordimgs_table wi on w.id = wi.belongs_to

-

Comments

Post a Comment

Popular posts from this blog

javascript - Thinglink image not visible until browser resize -

Image
i trying repurpose pre-existing theme, includes drop down menu displays image. trying embed thinglink drop down menu's content section, not visible until resize browser window. here menu looks like: then when clicked, can see empty space image should show: then when browser resized, image appears: this code content of menu: <div class="ajax_accordion_content" style="display: none;"> <div class="report-detail"> <table border="0" cellpadding="0" cellspacing="0" width="100%" class="table_basic"> <tbody> <!-- thinglink image embedded --> <img style="max-width: 100%;" src="http://cdn.thinglink.me/api/image/832705713204625409/1024/10/scaletowidth#tl-832705713204625409;1043138249'" class="alwaysthinglink"/> <script async charset="utf-8" src="http://cdn.thinglink.me/jse/embed.j...
Read more

firebird - Error "invalid transaction handle (expecting explicit transaction start)" executing script from Delphi -

i'm developing update app delphi 10. i'm running windows 7 64x, firebird 2.5.1.26351 32x. execution order: checks current version(select statement firebird database) downloads update(via ftp) apply it(.exe files, , execute .sql) error code -901 pops out when try execute .sql files. know there incompatibility issue w7 64x , fdb 32x, but, can everything: backup , restore(gbak), db commands(all). tried fdb 64x instead, , not working. code: //components fdwaitcursor: tfdguixwaitcursor; fddriverlink: tfdphysfbdriverlink; fdconnection:tfdconnection; fdscript: tfdscript; function tthr_script.createcomponents:boolean; begin try fddriverlink := tfdphysfbdriverlink.create(fddriverlink); fdwaitcursor := tfdguixwaitcursor.create(fdwaitcursor); fdconnection := tfdconnection.create(fdconnection); fdconnection begin drivername := 'fb'; params.username := thrbanco.bduser; params.password := thrbanco.bdpass; params.database := ...
Read more

Sound is not coming out while implementing Text-to-speech in Android activity -

i using texttospeak in 1 of app. while adding speech string texttospeech object instance, doesn't produce sound. though not getting error in log still sound not coming out. want device speak value of textview gets set resultmsg.settext() method. public class resultactivity extends activity { @override protected void oncreate(bundle savedinstancestate){ ............ resultmsg.settext(resultmsg_str); texttospeech = new texttospeech(getapplicationcontext(),newtexttospeech.oninitlistener(){ @override public void oninit(int status) { system.out.println("txt speech status = "+status); system.out.println("txt speech error status = "+texttospeech.error); system.out.println("txt speech success status = "+texttospeech.success); if(status == texttospeech.success){ texttospeech.setlanguage(locale.english); ...
Read more