Passing an array to sqlite WHERE IN clause via FMDB?

Question

Is it possible to pass an array to a SELECT … WHERE … IN statement via FMDB? I tried to implode the array like this:

NSArray *mergeIds; // An array with NSNumber Objects
NSString *mergeIdString = [mergeIds componentsJoinedByString:@","];

NSString *query = @"SELECT * FROM items WHERE last_merge_id IN (?)";
FMResultSet *result = [database executeQuery:query, mergeIdString];

This only works if there is exactly 1 object in the array, which leads me to believe that FMDB adds quotes around the whole imploded string.

So I tried passing the array as is to FMDB's method:

NSArray *mergeIds; // An array with NSNumber Objects
NSString *query = @"SELECT * FROM items WHERE last_merge_id IN (?)";
FMResultSet *result = [database executeQuery:query, mergeIds];

Which doesn't work at all.

I didn't find anything about it in the README or the samples on FMDB's github page.

Thanks, Stefan

Answer 1

I was having the same issue, and I figured it out, at least for my own app. First, structure your query like so, matching the number of question marks as the amount of data in the array:

NSString *getDataSql = @"SELECT * FROM data WHERE dataID IN (?, ?, ?)";

Then use the executeQuery:withArgumentsInArray call:

FMResultSet *results = [database executeQuery:getDataSql withArgumentsInArray:dataIDs];

In my case, I had an array of NSString objects inside the NSArray named dataIDs. I tried all sorts of things to get this SQL query working, and finally with this combination of sql / function call, I was able to get proper results.