in sqlite3 (node package), how to run multiple queries by sequence? - node.js

Question

I am using this pakcage: sqlite3 to manipulate database queries, code like this:
single query is quit simple:
var sqlite3 = require('sqlite3').verbose();
let db = new sqlite3.Database('database.sqlite3');
let entity_1_name = ''
db.serialize(function(){
db.get('select * from table1 where id = 1', function(error, row){
entity_1_name = row.name
})
})
db.close()
But how to execute multiple queries and in sequence?
(e.g. I want to run query1, then query2, then query3 )
just like:
var sqlite3 = require('sqlite3').verbose();
let db = new sqlite3.Database('database.sqlite3');
let entity_1_name = ''
let entity_2_name = ''
db.serialize(function(){
// this is query1
db.get('select * from table1 where id = 1', [], function(error, row){
entity_1_name = row.name
})
// this is query2
db.get('select * from table2 where dependency_column_name = ' + entity_1_name, function(error,row){
// this sql returns null value, because when this query was executed, the variable "entity_1_name" was not determined by query1.
})
})
db.close()

Answer 1

https://stackoverflow.com/a/40903302/16140221 May help you out
Their solution was to place each query within a function, then simply calling them.
(This is directly the code taken from the answer, it is not mine.)
function db_query1(your_param,...., callback){
　　// database operation
db.run( sql , [param,...] , function(err,rows){
if(err) // return
else{
// get rows with callback
callback(null, rows);
}
});
}
function db_query2(your_param,...., callback){
　　// database operation
db.run( sql , [param,...] , function(err,rows){
if(err) // return
else{
// get rows with callback
callback(null, rows);
}
});
}
Then calling the functions
db_query1(....,function(err,result1){
if(err) ...// return
// do the things with result1
// And then call query2
db_query2(....,function(err,result2){
if(err) ...// return
// do the things with result1
});
});

Answer 2

OK, at last, I used promise + async + await to make it done.
Step1. define a function return new Promise()
do_query_1(material_name){
// 1. return this new Promise()
return new Promise( (resolve, reject) => {
let db = this.$database_tool.get_db()
let that = this
db.serialize(function(){
db.get(`select * from table1 where id = 1`, [], function(error, row){
// 2. this is the point, put anything you want to result to resolve()
resolve(row.id)
})
})
db.close();
})
},
Step2. define a async function, to call the method defined in Step1.
async do_query_2(){
let that = this
// other lines was omitted.
// HERE , use await to get the result from STEP1.
let entity_1_name = await that.do_query_1(row.material_name)
db.serialize(function(){
let sql = `'select * from table2 where dependency_column_name = ' + entity_1_name`
db.run(sql)
})
db.close();
},
Step3. call do_query_2() in normal way:
do_query_2()
That's it!