在SQL中格式化true / false

Question

I am passing a dict that I get from mysql directly into json. Unfortunately, the json fails when trying to parse the boolean with the following error:

'Current token (VALUE_NUMBER_INT) not of boolean type

Is the following the preferred way to cast a TINYINT(1) to a javascript boolean?

if(tm.is_live, 'true', 'false') live_for_preorder,

Answer 1

I seem to recall MySQL is one of those rare databases that lets you use IF in normal SELECT statements where most dbms would insist on case, IF being reserved for control flow

As such it appears that MySQL is telling you you're not providing IF with a Boolean when it wants one. Convert your statement to a comparison that returns a Boolean:

if(tm.is_live=1, 'true', 'false') live_for_preorder,

(If you're using 1 for true and 0 for false)

To make your db skill set more portable it would be good to get into the habit of using CASE rather than IF in select queries:

CASE tm.is_live WHEN 1 THEN 'true' ELSE 'false' END live_for_preorder,

CASE WHEN tm.is_live = 1 THEN 'true' ELSE 'false' END live_for_preorder,

A case can have any number of WHEN, but you can't mix the forms, it's either CASE variable WHEN comparevalue THEN outputvalue [when when when else] END Or it's CASE WHEN test THEN output [when when when else] END

Answer 2

If you want to convert to a MySQL boolean, simply do:

select (tm.is_live <> 0) as live_for_preorder,

If this is accepted by Javascript, then this would be the simplest solution.