UPDATE book as b
left JOIN supply as s on s.XXXX = b.XXXX
SET
    b.amount = b.amount + coalesce(s.amount,0),
    b.price = (b.price + coalesce(s.price,b.price))/2

js
/**
 * To quants satoshi, wei, etc...
 *
 * @param {Number|String|BN} value
 * @return {String}
 */
export function toMinimal (value, decimal) {
  if (typeof decimal !== 'number') {
    throw new TypeError('toMinimal error: decimal is not a number')
  }

  // hook for modify value like 1e-8
  if (value.toString().indexOf('e') > 0) {
    const valueParts = String(value).match(/^([\d.]+)e-?(\d+)$/)

    value = `0.${new Array(parseInt(valueParts[2], 10)).join('0')}${valueParts[1].replace('.', '')}`
  }

  const [integerPart, fractionPart = ''] = value.toString().split(/[,.]/)
  const paddedFraction = fractionPart.length < decimal
    ? fractionPart.padEnd(decimal, '0')
    : fractionPart.substr(0, decimal)
  const result = `${integerPart}${paddedFraction}`.replace(/^0+/, '')

  if (result === '') {
    return '0'
  }

  return result
}

/**
 * To currency unit.
 *
 * @param {String|Number|BN} value
 * @return {String}
 */
// eslint-disable-next-line no-shadow
export function toCurrency (value, decimal) {
  if (typeof value === 'string') {
    if (value.indexOf('.') !== -1) {
      throw new Error(`${value} must not contain '.'`)
    }
    if (value.indexOf('-') !== -1) {
      throw new Error(`${value} must not contain '-'`)
    }
    if (typeof decimal !== 'number') {
      throw new TypeError('toCurrency error: decimal is not a number')
    }
  }

  const valueBN = new BN(value)

  if (valueBN.lte(0)) {
    throw new Error('negative')
  }
  const valueString = new BN(value).toString()

  const integerPart = valueString
    .substring(0, valueString.length - decimal)
    .replace(/^0+/, '') || 0

  const fractionPart = valueString.substring(valueString.length - decimal)
    .padStart(decimal, '0')
    .replace(/0+$/, '')

  if (fractionPart.search('-') !== -1) {
    console.warn('convert: toCurrency: fractionPart is bad')
  }

  if (fractionPart !== '') {
    return `${integerPart}.${fractionPart}`
  }

  return `${integerPart}`
}