cordova - How to check whether data exists and insert by one query in websql? -

can have 1 full query check whether data has been in database , insert if not?

i believe can done in normal sql using transaction.

the consideration not manual select query insert have more 1 table done.

since websql implementation of sqlite, use insert or ignore manage conflict resolution in single transaction.

for example, if had following table:

create table data (id integer primary key, event_id integer, track_id integer, value integer); create unique index data_idx on data(event_id, track_id); 

which contained data:

1|1|2|3 2|2|3|4 

you issue following sequential statements:

insert or ignore data values (null, 1, 2, 3); insert or ignore data values (null, 2, 3, 5); insert or ignore data values (null, 3, 4, 5); 

and result of select * data be:

1|1|2|3 2|2|3|4 3|3|4|5 

the existing rows not updated because of constraint violation, first 2 statements ignore instead of fail, third execute , third row inserted.