如何在Azure表存储中查找与值数组不匹配的记录？

Question

I'm trying to perform a 'doesNotContainAllObjectsInArray' type operation on Azure Mobile Services. For example, let's say I have a table called Number and within that table are these records with these 'number' values: 11111, 22222, 33333, 44444.

I want to be able to write a query that will allow me to pass in an array of numbers that I specifically don't want, for example: [11111,44444] should yield me with [22222, 33333] .

I've tried using JavaScript in my where operator, but I'm getting an error back stating that the expression isn't supported. This is what I've tried:

var numberTable = tables.getTable('Number');
var ignoreNumbers = ['11111', '44444'];
numberTable.where(function(numbers) {
    return (numbers.indexOf(this.number) > -1);
}, ignoreNumbers).read({
    success: function(foundNumbers) {
        console.log('Found ' + foundNumbers.length + ' numbers!');
    },
    error: function(error) {
        console.error('Error with query! ' + error);
    }
});

Note: I can't hard code the ignoreNumbers values, since that array is produced from a previous query.

Can anyone recommend how I might go about executing a query like this? Would I need build a SQL statement and execute it with mssql ? (...is that even possible with Table Storage?)

Answer 1

You are describing the SQL Except operator which isn't supported in Table Queries . The only way I've found to do this is to load the table into memory (often not feasible due to size) and then use LINQ to do an Except query.

Answer 2

I managed to solve this by creating a SQL query and executing it through the request.service.mssql object, something like this:

SELECT * FROM Number WHERE (number != '11111' && number != '22222')

The WHERE part of the query is built by iterating the ignoreNumbers array and building the SQL statement by string concatenation.

Not sure if it's the most efficient thing in the world, but in reality there are only going to be a couple of numbers (maybe 5-10) and so far it seems to work.