CODEWITHSUNDEEP
node.jssqliteknex.js
Ivan Kelber
Ivan Kelber

Reputation: 336

Access column value from within knex query

I'd like to update the value of column A by applying a function to column B.

Is there a simple solution of the form:

knex('table')
    .update({
      colA: func(${colB})
    })

Upvotes: 0

Views: 1442

Answers (1)

GaryL
GaryL

Reputation: 1460

Yes, there is a way to do this within Knex.

For SQL functions which don’t have explicit support in Knex you use knex.raw(SQLstring, parmArray) to encapsulate a SQL snippet or knex.schema.raw(...) to produce an entire SQL statement. And you use single question marks ? for value replacements, and double question marks ?? for field identifier replacements. (see link)

So the SQL: UPDATE table SET colA = func(colB)

... can be produced by including a SQL snippet: (you were close)

knex('table')
    .update({
       colA: knex.raw( 'func(??)', ['colB'] ) 
     })

... or as full raw SQL:

knex.schema.raw( 'UPDATE table SET ?? = func(??)', ['colA', 'colB'] )

Cheers, Gary.

Upvotes: 2

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