Sequelize - subquery in where clause

问题

I'm using Sequelize in my Express app. I need to generate a query that has a subquery in the WHERE clause.

SELECT *
  FROM MyTable
 WHERE id NOT IN (
       SELECT fkey
         FROM MyOtherTable
        WHERE field1 = 1
          AND field2 = 2
          AND field3 = 3
       )

I first tried relations/associations through my models but couldn't get it to work. Something like:

MyTable.find( {
    where: {
        id: {
            $notIn: // <= what goes here? Can I somehow reference my include model?
        }
    },
    include: [ {
        model: MyOtherTable,
        where: {
            field1: 1,
            field2: 2,
            field3: 3
    } ]
} );

Then I tried using Sequelize.where(), no luck there.

Then I tried Sequelize.literal() and that works but not sure if it's a "proper" way of doing a subquery in a where clause in Sequelize as I'm new to it.

MyTable.find( {
    where: {
        id: {
            $notIn: sequelize.literal( 
                '( SELECT fkey ' +
                    'FROM MyOtherTable ' +
                   'WHERE field1 = ' + field1 +
                    ' AND field2 = ' + field2 +
                    ' AND field3 = ' + field3 + 
                ')'
        }
    } 
} );

I also know that I could use Sequelize.query() but don't really know if I should reach for it or if literal()is the right away as I feel like there's something I'm overlooking.

I would really like to know how to perform a subquery in a WHERE clause with Sequelize the "proper" way.

Thanks for the feedback!

回答1:

I have encountered a similar issue in my project. The way I choose to implement it is a bit different for two reasons:

If at one point in time Sequelize decides to implement sub queries - the syntax is ready.
Use Sequelize protection agains SQL injection.

Here is my code snippet, hope it helps.

const tempSQL = sequelize.dialect.QueryGenerator.selectQuery('MyOtherTable',{
    attributes: ['fkey'],
    where: {
         field1: 1,
         field2: 2,
         field3: 3
    }})
    .slice(0,-1); // to remove the ';' from the end of the SQL

MyTable.find( {
    where: {
        id: {
             $notIn: sequelize.literal('(' + tempSQL + ')'),
        }
    } 
} );

Some people might choose to not use the tempSQL variable and simply build the SQL inside the find structure (maybe using a helper method?)

I also think this might be the basis for a sub queries extension for sequelize as it uses the same syntax almost.

来源：https://stackoverflow.com/questions/36164694/sequelize-subquery-in-where-clause

标签

orm

subquery

where-clause

sequelize.js