Develop Reference

JavaScript MySql INSERT statement for multiple rows through URL

Good day !
I am trying to send an object array to my MySql Database through an url using an API.
Here is the code on my API :
app.get("/orderdetails/add", (req, res) => {
const {
item__,
Qty_Ordered,
Unit_Price,
Ext_Price
} = req.query;
const INSERT_ORDERDETAILS_QUERY = `INSERT INTO oe_details (item__,
Qty_Ordered, Unit_Price, Ext_Price) VALUES('${item__}', '${Qty_Ordered}',
'${Unit_Price}', '${Ext_Price}')`;
connection1.query(INSERT_ORDERDETAILS_QUERY, (err, results) => {
if (err) {
return res.send(err);
} else {
return res.send("successfully added order details");
}
});
});
And below is the function on my App :
addOrderDetails = _ => {
const o = this.props.o;
const summary = o.filter(function(obj) {
return obj.Quantity >= 1;
});
var url = "";
summary.forEach(function(e) {
url +=
"item__=" +
e.ExternalID +
"&Qty_Ordered=" +
e.Quantity +
"&Unit_Price=" +
e.Price +
"&Ext_Price=" +
e.ExtPrice +
"&";
});
url = url.trim("&");
fetch(`http://localhost:4000/orderdetails/add?${url}`).catch(err =>
console.error(err)
);
};
When I run addOrderDetails, I end up sending the following statement to MySql:
INSERT INTO oe_details (item__, Qty_Ordered, Unit_Price, Ext_Price)
VALUES('B-2080,B-2081', '8,5', '18.75,18.75', '150,93.75')
Which is wrong... is there a way for me to add multiple rows to mysql database using the same concept ?
it works fine if I only have 1 row to add...
Help would be greatly appreciated !
Thanks,

To insert multiple rows, MySQL statement should be like
INSERT INTO oe_details (item__, Qty_Ordered, Unit_Price, Ext_Price)
VALUES('B-2080,B-2081', '8,5', '18.75,18.75', '150,93.75'),
VALUES('C-2080,C-2081', '8,5', '18.75,18.75', '150,93.75'),
VALUES('B-2080,B-2081', '8,5', '18.75,18.75', '150,93.75');
You can change your API to a POST call and send an array of your data to it, and within your API you can form the above query.
You can use a simple for loop to create such query.
let summary = [1,2,3,4] // dummy data
let INSERT_ORDERDETAILS_QUERY = `INSERT INTO oe_details (item__, Qty_Ordered, Unit_Price, Ext_Price) VALUES`
summary.forEach(function(data, i) {
INSERT_ORDERDETAILS_QUERY = `${INSERT_ORDERDETAILS_QUERY} (${data})`;
INSERT_ORDERDETAILS_QUERY = (i !== summary.length - 1) ? `${INSERT_ORDERDETAILS_QUERY}, ` : `${INSERT_ORDERDETAILS_QUERY};`;
})
Hope this helps!

Simplify nested promises within loops and closures

I wrote a ~50 lines script to perform housekeeping on MySQL databases. I'm afraid my code exhibits anti-patterns as it rapidly escalates to an unreadable mess for the simple functions it performs.
I'd like some opinions for improving readability.
The full script is at the bottom of this post to give an idea.
Spotlight on the problem
The excessive nesting is caused by patterns like this repeated over and over: (snippet taken from script)
sql.query("show databases")
.then(function(rows) {
for (var r of rows) {
var db = r.Database;
(function(db) {
sql.query("show tables in " + db)
.then(function(rows) {
// [...]
}
})(db);
}
});
I'm nesting one promise under the other within both a for loop and a closure. The loop is needed to iterate across all results from sql.query(), and the closure is necessary to pass the value of db to the lower promise; without the closure, the loop would complete even before the nested promise executes at all, so db would always contain only the last element of the loop, preventing the nested promise from reading each value of db.
Full script
var mysql = require("promise-mysql");
var validator = require("mysql-validator"); // simple library to validate against mysql data types
var ignoreDbs = [ "information_schema" ],
multiplier = 2, // numeric records multiplier to check out-of-range proximity
exitStatus = {'ok': 0, 'nearOutOfRange': 1, 'systemError': 2};
(function() {
var sql,
mysqlHost = "localhost",
mysqlUser = "user",
mysqlPass = "";
mysql.createConnection({
host: mysqlHost,
user: mysqlUser,
password: mysqlPass
}).then(function(connection) {
sql = connection;
})
.then(function() {
sql.query("show databases")
.then(function(rows) {
for (var r of rows) {
var db = r.Database;
if (ignoreDbs.indexOf(db) != -1) continue;
(function(db) {
sql.query("show tables in " + db)
.then(function(rows) {
for (var r of rows) {
var table = r["Tables_in_" + db];
(function(table) {
sql.query("describe " + db + "." + table)
.then(function(rows) {
for (var r of rows) {
(function(r) {
var field = r.Field,
type = r.Type, // eg: decimal(10,2)
query = "select " + field + " from " + db + "." + table + " ";
if (table != "nonce") query += "order by date desc limit 1000";
sql.query(query)
.then(function(rows) {
for (var r of rows) {
var record, err;
// remove decimal part, only integer range is checked
record = Math.trunc(r[field]);
err = validator.check(record * multiplier, type);
if (err) {
console.log(err.message);
process.exit(exitStatus.nearOutOfRange);
}
}
});
})(r);
}
});
})(table);
}
});
})(db);
}
});
})
.then(function() {
// if (sql != null) sql.end(); // may not exit process here: sql connection terminates before async functions above
//process.exit(exitStatus.ok); //
});
})();
Trivia
The purpose of the script is to automatically and periodically monitor if any record stored in any row, table and database in MySQL is approaching the out-of-range limit for its specific data type. Several other processes connected to MySQL continuously insert new numeric data with increasing values and nonces; this script is a central point where to check for such numeric limits. The script would then be attached to Munin for continuous monitoring and alerting.
Update: Revised script
As suggested by #Kqcef I modularized the anonymous functions out of the promise nest, and used let to avoid the explicit nesting of an additional function to preserve variable context.
Still this is excessively verbose, previously I wrote the same script in Bash in about 40 lines, but performance was screaming for a port to nodejs.
"use strict";
var mysql = require("promise-mysql");
var validator = require("mysql-validator"); // a simple library to validate against mysql data types
var ignoreDbs = [ "information_schema" ],
multiplier = 2, // numeric records multiplier to check out-of-range proximity
exitStatus = {'ok': 0, 'nearOutOfRange': 1, 'systemError': 2};
var mysqlHost = "localhost",
mysqlUser = "btc",
mysqlPass = "";
// return array of DBs strings
function getDatabases(sql) {
return sql.query("show databases")
.then(function(rows) {
var dbs = [];
for (var r of rows)
dbs.push(r.Database);
return dbs;
});
}
// return array of tables strings
function getTables(sql, db) {
return sql.query("show tables in " + db)
.then(function(rows) {
var tables = [];
for (var r of rows)
tables.push(r["Tables_in_" + db]);
return tables;
});
}
// return array of descriptions
function getTableDescription(sql, db, table) {
return sql.query("describe " + db + "." + table)
.then(function(rows) {
var descrs = [];
for (var r of rows) {
descrs.push({ 'field': r.Field, // eg: price
'type': r.Type}); // eg: decimal(10,2)
}
return descrs;
});
}
// return err object
function validateRecord(record, type) {
var record, err;
if (typeof record != "number") {
console.log("error: record is not numeric.");
process.exit(exitStatus.systemError);
}
// remove decimal part, only integer range is checked
record = Math.trunc(record);
err = validator.check(record * multiplier, type);
return err;
}
(function() {
var sql;
mysql.createConnection({
host: mysqlHost,
user: mysqlUser,
password: mysqlPass
}).then(function(connection) {
sql = connection;
})
.then(function() {
return getDatabases(sql)
})
.then(function(dbs) {
dbs.forEach(function(db) {
if (ignoreDbs.indexOf(db) != -1) return;
getTables(sql, db)
.then(function(tables) {
tables.forEach(function(table) {
getTableDescription(sql, db, table)
.then(function(descrs) {
descrs.forEach(function(descr) {
let field = descr.field,
type = descr.type,
query = "select " + descr.field + " from " + db + "." + table + " ";
if (table != "nonce") query += "order by date desc limit 1000";
sql.query(query)
.then(function(rows) {
rows.forEach(function(row) {
let err = validateRecord(row[field], type);
if (err) {
console.log(err.message);
process.exit(exitStatus.nearOutOfRange);
}
});
});
});
});
});
});
});
});
/*
.then(function() {
//if (sql != null) sql.end();
//process.exit(exitStatus.ok);
});
*/
})();

I agree with Jaromanda in terms of using let in your for loops to block scope the values and avoid your usage of an immediately-invoked function, which, while totally fine in terms of functionality, is decidedly less readable.
In terms of best practices and avoiding anti-patterns, one of the most important things you can strive for in terms of writing 'good' code is building modularized, reusable blocks of code. As it stands, your code has 5 or 6 anonymous functions that exist nowhere but within your chain of promise callbacks. If you were to declare those as functions outside of that chain, not only does that improve the maintainability of your code (you can test each individual one), but, if their names are clearly indicative of their purposes, would make for a very readable promise chain.
(Updated based on User Question)
Rather than leaving inner functions...
function getTableDescription(sql, db, table) {
return sql.query("describe " + db + "." + table)
.then(function(rows) {
var descrs = [];
for (var r of rows) {
descrs.push({ 'field': r.Field, // eg: price
'type': r.Type}); // eg: decimal(10,2)
}
return descrs;
});
}
...you can easily strip that out so that your code is self-documenting:
function collectDescriptionsFromRows(rows) {
var descriptions = [];
for (var row of rows) {
descriptions.push({'field': row.Field, 'type': row.Type});
}
return descriptions;
}
function getTableDescription(sql, db, table) {
return sql.query("describe " + db + "." + table)
.then(collectDescriptionsFromRows);
}
Also, if you ever find yourself doing data collection from one array to another, it's extremely helpful to get used to using built-in higher order functions (map, filter, reduce). Instead of the collectDescriptionsFromRows I just listed, it could be simplified to:
function collectDescriptionsFromRows(rows) {
return rows.map(row => { 'field': row.Field, 'type': row.Type});
}
Much less verbose, much more readable. Your code and promise-chain will shrink and read more like a step-by-step list of instructions if you continue to extract those anonymous functions in the chain. Anywhere you see function(...there is more extracting to do! You can also do some damage (positively) by extracting all the data you need to begin with and use local logic to boil it down to what you need, rather than making several queries. Hope this helps.

Node-postgres Inserting a new record into my database does not return the new entry's data

Here's the route from which the query is being executed:
userRouter.route("/new")
.post(function (req, res) {
var user = req.body;
pg.connect(connectionString, function (error, client, done) {
var queryString = "INSERT INTO Users (id, first_name, last_name) VALUES (" + "'" + [user.id, user.first_name, user.last_name].join("','") + "'" + ")";
console.log(queryString);
client.query(queryString, function (error, result) {
console.log(result.rows);
done();
});
});
});
The problem is that the "result" value I'm attempting to reference from within the second console is basically blank:
{
command: 'INSERT',
rowCount: 1,
oid: 0,
rows: [],
fields: [],
_parsers: [],
RowCtor: null,
rowAsArray: false,
_getTypeParser: [Function: bound ]
}
Shouldn't result.rows contain an array containing an object representing the row I just created in the database?

All right, I've figured it out.
Apparently, I was attempting to use a feature that has not yet been implemented in Node-Postgres, as described here: https://github.com/brianc/node-postgres/wiki/Todo
Insert/update/select row count in query result callback
Though this would be extremely awesome off course, it is possible to
obtain the behaviour by adding RETURNING id or even RETURNING * to the
query. This works fine for single columns for me. I will test this for
multiples and the handling of that case by this package. I am quite
certain it must be possible in postgres.
So, I updated my query to return all data for the new row:
var queryString = "INSERT INTO Users (first_name, last_name) VALUES (" + "'" + [user.first_name, user.last_name].join("','") + "'" + ") RETURNING *";
And then I modified my query to account for the "row" event handler, which is trigger when a new row is entered into the database. It is within the context of this event handler that the new row data is accessible to me (as per the "RETURNING" parameter above:
var query = client.query(queryString, function (error, result) {
done();
});
query.on("row", function (row, result) {
console.log("Inside the row event handler.");
res.render("users/show", { user: row });
});
Aaaand it works!

update the query and add at the end of the query " RETURNING * "
var queryString = "INSERT INTO Users (id, first_name, last_name) VALUES (" + "'" + [user.id, user.first_name, user.last_name].join("','") + "'" + ") RETURNING *";
get result.rows[0]

Node-firebird sequentially select

I am trying to get the data from Firebird DB with sequentially select option. I would like to get the first 500 rows, as you see on my code. And for testing, I am increasing 'k' for each 'row' and logging 'k' and
'md5' to the console.
When I am running my code, it gives me random number of rows. But the number of rows are always more than 500.
How can I solve this problem? Any suggestions?
var Firebird = require('node-firebird');
var md5 = require('md5');
var options = {};
//options.host = '127.0.0.1';
//options.port = 3050;
options.database = '/Users/bla/mydb.FDB';
options.user = 'SYSDBA';
options.password = 'masterkey';
var pool = Firebird.pool(10, options);
var k = 0;
pool.get(function (err, db) {
if (err)
throw err;
db.sequentially('SELECT FIRST 500 SOME QUERY', function (row, index) {
k = k + 1;
console.log(k + ' => ' + md5(JSON.stringify(row)) + '\n');
}, function (err) {
db.detach();
});
});

Please check the link above:
https://github.com/hgourvest/node-firebird/issues/78
#sdnetwork sdnetwork commented an hour ago it's a bug in node-firebird, i have a fix for this problem. i will post it soon here. (try with that https://github.com/sdnetwork/node-firebird)

depending upon the version of firebird, "select first n" may give an error unless you also include an "order by" clause

SQL Insert Statement not Working in Javascript

I'm trying to get my WebSQL database to popluate using a JSON array (Object is called myJSONObject, array is called costcodes).
The function runs on click, the database successfully creates, but the data is not inserted into the database. It doesn't even throw and error, it just doesn't do anything.
My initial thought was that the data isn't escaped properly, but I don't know exactly where/how to escape it. So I'm stumped.
localDB = null;
function initDB()
{
if (localDB==null)
{
var shortName = 'Costcode';
var version = '1.0';
var displayName = 'Costcode';
var maxSize = 217802; // in bytes
localDB = window.openDatabase(shortName, version, displayName, maxSize);
}
}
function buildTable()
{
var sQuery = 'CREATE TABLE IF NOT EXISTS Costcode ('+
'id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,' +
'cost_code_no VARCHAR NULL,' +
'row_unique_no VARCHAR NULL,' +
'cost_class_no VARCHAR NULL,' +
'Table_Version VARCHAR DEFAULT "1.0");';
try
{
initDB();
localDB.transaction(function(transaction)
{
transaction.executeSql(sQuery, []);
console.log('sucess');
});
}
catch (e)
{
alert("Error: Unable to create table 'x" + "' " + e + ".");
return;
}
}
function exeSQLFast()
{
initDB();
localDB.transaction(function(transaction)
{
for (var x = 0; x <myJSONObject.costcodes.length; x++)
{
var costcodeno = myJSONObject.costcodes[x].cost_code_no;
var rowuniqueid = myJSONObject.costcodes[x].row_unique_id;
var costclassno = myJSONObject.costcodes[x].cost_class_no;
console.log(costcodeno);
console.log(rowuniqueid);
console.log(costclassno);
transaction.executeSql('INSERT INTO Costcode (cost_code_no, row_unique_id, cost_class_no) VALUES (? , ? , ?)',
[costcodeno,
rowuniqueid,
costclassno]
, function(transaction, results)
{
console.log(costcodeno);
console.log('hooray');
}
)};
}
)}
</script>
</head>
<body onLoad="buildTable();">
<input type="button" onClick="exeSQLFast();" value='button'>
</body>
</html>
The console log shows that the variables are all being properly defined, but it's not running the insert statement. Any ideas?
Here's an example of myJSONObject.costcodes[2]
cost_class_no: " 3"
cost_code_no: " 1000"
row_unique_id: 335
That looks like a problem doesn't it...

The problem was that I called the row_unique_no column row_unique_id in the insert statement. Now I feel stupid.
But if anyone is curious how to populate a WebSQL database properly, this is how you do it. Just don't mistype the column names.