Syntax required for conditional variable use to modify SQL query in Node.JS - sql

Question

I've fairly new to NodeJS, and I'm not sure of the best method or syntax to create an MS SQL query with conditional code. Here's what I want to do, with the query greatly simplified, and using some pseudocode:
// #route GET /api/flow/data/references
async function getDataReferences(req, res) {
const { station, type } = req.query
let pool
try {
pool = await sql.connect(config)
const { recordset } = await pool
.request()
.input('station', sql.NVarChar(50), station).query`
SELECT Reference
FROM TABLE
WHERE Status = 'Done' ` +
if(type === 1) {
`AND Station_1 = #station`
} else if(type === 2) {
`AND Station_2 = #station`
} else {
`AND Station_3 = #station`
}
+ `AND Process = 5`
const processedData = recordset.map((item) => item.Reference)
res.json(processedData)
} catch (error) {
console.log(
`ERROR with Station: ${station} with Type: ${type}`,
error.message,
new Date()
)
res.status(500).json({ message: error.message })
} finally {
await pool.close()
}
}
Depending on the value of "type" supplied to the function, I want the query to reference a different DB column.
UPDATE:
So I've found that the following works, although arguably the formatting isn't quite as nice.
// #route GET /api/flow/data/references
async function getDataReferences(req, res) {
const { station, type } = req.query
let station_column
if(type === 1) {
station_column = 'AND Station_1 = #station'
} else if(type === 2) {
station_column = 'AND Station_2 = #station'
} else {
station_column = 'AND Station_3 = #station'
}
let query = `
SELECT Reference
FROM TABLE
WHERE Status = 'Done'
${station_column}
AND Process = 5`
let pool
try {
pool = await sql.connect(config)
const { recordset } = await pool
.request()
.input('station', sql.NVarChar(50), station).query(query)
const processedData = recordset.map((item) => item.Reference)
res.json(processedData)
} catch (error) {
console.log(
`ERROR with Station: ${station} with Type: ${type}`,
error.message,
new Date()
)
res.status(500).json({ message: error.message })
} finally {
await pool.close()
}
}
I tried just using the template literal substitutions directly in the query, but that wouldn't work. (Perhaps for reasons stated here: https://github.com/tediousjs/node-mssql#es6-tagged-template-literals )
If I don't get any better answer, I'll post this as the answer; but would like to know if there's a best practice method for doing this.

Answer 1

Seems like this works, and isn't overly complicated:
// #route GET /api/flow/data/references
async function getDataReferences(req, res) {
const { station, type } = req.query
let station_column
if(type === 1) {
station_column = 'AND Station_1 = #station'
} else if(type === 2) {
station_column = 'AND Station_2 = #station'
} else {
station_column = 'AND Station_3 = #station'
}
let query = `
SELECT Reference
FROM TABLE
WHERE Status = 'Done'
${station_column}
AND Process = 5`
let pool
try {
pool = await sql.connect(config)
const { recordset } = await pool
.request()
.input('station', sql.NVarChar(50), station).query(query)
const processedData = recordset.map((item) => item.Reference)
res.json(processedData)
} catch (error) {
console.log(
`ERROR with Station: ${station} with Type: ${type}`,
error.message,
new Date()
)
res.status(500).json({ message: error.message })
} finally {
await pool.close()
}
}
Essentially, create the full query string in advance, including the parameters to bind, and then pull that whole string in as the query.