I used to name my parameters in my SQL query when preparing it for practical reasons like in php with PDO.
So can I use named parameters with node-postgres module?
For now, I saw many examples and docs on internet showing queries like so:
client.query("SELECT * FROM foo WHERE id = $1 AND color = $2", [22, 'blue']);
But is this also correct?
client.query("SELECT * FROM foo WHERE id = :id AND color = :color", {id: 22, color: 'blue'});
or this
client.query("SELECT * FROM foo WHERE id = ? AND color = ?", [22, 'blue']);
I'm asking this because of the numbered parameter $n that doesn't help me in the case of queries built dynamically.
There is a library for what you are trying to do. Here's how:
var sql = require('yesql').pg
client.query(sql("SELECT * FROM foo WHERE id = :id AND color = :color")({id: 22, color: 'blue'}));
QueryConvert to the rescue. It will take a parameterized sql string and an object and converts it to pg conforming query config.
type QueryReducerArray = [string, any[], number];
export function queryConvert(parameterizedSql: string, params: Dict<any>) {
const [text, values] = Object.entries(params).reduce(
([sql, array, index], [key, value]) => [sql.replace(`:${key}`, `$${index}`), [...array, value], index + 1] as QueryReducerArray,
[parameterizedSql, [], 1] as QueryReducerArray
);
return { text, values };
}
Usage would be as follows:
client.query(queryConvert("SELECT * FROM foo WHERE id = :id AND color = :color", {id: 22, color: 'blue'}));
Not exactly what the OP is asking for. But you could also use:
import SQL from 'sql-template-strings';
client.query(SQL`SELECT * FROM unicorn WHERE color = ${colorName}`)
It uses tag functions in combination with template literals to embed the values
I have been working with nodejs and postgres. I usually execute queries like this:
client.query("DELETE FROM vehiculo WHERE vehiculo_id= $1", [id], function (err, result){ //Delete a record in de db
if(err){
client.end();//Close de data base conection
//Error code here
}
else{
client.end();
//Some code here
}
});
Related
I have the following SQL query, which works:
await sequelize.query(
"DELETE FROM `table_name` WHERE (?) IN (?)",
{
replacements: ["project_id", projectIds],
type: QueryTypes.DELETE,
}
);
But I also want to use a replacement for table_name like this:
await sequelize.query(
"DELETE FROM (?) WHERE (?) IN (?)",
{
replacements: ["table_name", "project_id", projectIds],
type: QueryTypes.DELETE,
}
);
But this doesn't work and generates an error about SQL syntax. How can I make this work?
You are mixing data value binding and quoting identifiers.
There is ancient issue in the repo: https://github.com/sequelize/sequelize/issues/4494, which sounds like the problem above.
I believe you can create a workaround that respects different sql dialects like this:
const queryInterface = sequelize.getQueryInterface();
const tableName = queryInterface.quoteIdentifier("projects");
const columnName = queryInterface.quoteIdentifier("project_id");
await sequelize.query(`DELETE FROM ${tableName} WHERE ${columnName} IN (?)`, {
replacements: [project_ids],
type: QueryTypes.DELETE,
});
Assuming you are using sequelize 6.x.
When building a complex SQL query for Laravel, using ? as placeholders for parameters is great. However when the value is null, the SQL syntax needs to be changed from = ? to IS NULL. Plus, since the number of parameters is one less, I need to pass a different array.
To get it to work, I have written it like this, but there must be a better way:
if ($cohortId === null) {
// sql should be: column IS NULL
$sqlCohortString = "IS NULL";
$params = [
Carbon::today()->subDays(90),
// no cohort id here
];
} else {
// sql should be: column = ?
$sqlCohortString = "= ?";
$params = [
Carbon::today()->subDays(90),
$cohortId
];
}
$query = "SELECT items.`name`,
snapshots.`value`,
snapshots.`taken_at`,
FROM snapshots
INNER JOIN (
SELECT MAX(id) AS id, item_id
FROM snapshots
WHERE `taken_at` > ?
AND snapshots.`cohort_id` $sqlCohortString
GROUP BY item_id
) latest
ON latest.`id` = snapshots.`id`
INNER JOIN items
ON items.`id` = snapshots.`item_id`
ORDER by media_items.`slug` ASC
";
$chartData = DB::select($query, $params);
My question is: does Laravel have a way to detect null values and replace ? more intelligently?
PS: The SQL is for a chart, so I need the single highest snapshot value for each item.
You can use ->when to create a conditional where clause:
$data = DB::table('table')
->when($cohortId === null, function ($query) {
return $query->whereNull('cohort_id');
}, function ($query) use ($cohortId) {
// the "use" keyword provides access to "outer" variables
return $query->where('cohort_id', '=', $cohortId);
})
->where('taken_at', '>', $someDate)
->toSql();
How can i dynamically change the selected columns in the generated sql query when using a linq expression?
Its a new session for each time the query is executed.
Even when I set the MapExp as null after first creation an then changing the bool value to false, it still generates the column in the sql query.
The code runs in a wpf application.
System.Linq.Expressions.Expression<Func<Entity, Model>> MapExp = x => new Model
{
Id=xId,
Count= LoadFormulaField ? x.Count: null,
...
};
var result = session.Query<Entity>().Select(MapExp))
Your problem seems to be the ternary-conditional as part of the expression which is causing the "Count" column to always be queried.
One option to avoid this could be:
var query = session.Query<Entity>();
IQueryable<Model> result = null;
if (LoadFormulaField)
{
result = query.Select(x => new Model
{
Id = x.Id,
Count = x.Count,
});
}
else
{
result = query.Select(x => new Model
{
Id = x.Id,
});
}
Which would get a little less ugly if you separate in a couple of methods I think.
I have several tables that have JSON arrays stored within fields.
Using PHP PDO I am able to retrieve this data without issue using:
$query1 = $database->prepare("SELECT * FROM module_settings
WHERE project_token = ? AND module_id = ? ORDER BY id DESC LIMIT 1");
$query1->execute(array($page["project_token"], 2));
$idx = $query1->fetch(PDO::FETCH_ASSOC);
$idx["settings"] = json_decode($idx["settings"]);
This returns a string like:
{"mid":"","module_id":"1","force_reg_enable":"1","force_reg_page_delay":"2"}
Attempting to gather the same data via PhalconPHP
$result = Modulesettings::findFirst( array(
'conditions' => 'project_token = "' . $token . '"' ,
'columns' => 'settings'
) );
var_dump($result);
Provides a result of
object(Phalcon\Mvc\Model\Row)#61 (1) { ["settings"]=> string(167) "{"text":"<\/a>
<\/a>
","class":""}" }
What do I need to do different in Phalcon to return the string as it is stored in the table?
Thank you.
You have 2 approach
First :
Get the settings with this structure :
$settings = $result->settings;
var_dump($settings);
Second :
First get array from resultset, then using the array element :
$res = $result->toArray();
var_dump($res['settings']);
Try it.
You can decode json right in your Modulesettings model declaration:
// handling result
function afterFetch() {
$this->settings = json_decode($this->settings);
}
// saving. Can use beforeCreate+beforeSave+beforeUpdate
// or write a Json filter.
function beforeValidation() {
$this->settings = json_encode($this->settings);
}
I have the following query:
val = val.Select(item => new SimpleBill { CTime = item.CTime, Description = item.Description, ID = item.ID,
IDAccount = item.IDAccount, OrderNumber = item.OrderNumber, PSM = item.PSM, Sum = item.Sum,
Type = (BillType)item.Type,
ByteStatus = ((Bill)item).Payments.OrderByDescending(payment => payment.ID).FirstOrDefault().Status,
LastPaymentDate = ((Bill)item).Payments.OrderByDescending(payment => payment.ID).FirstOrDefault().CTime,
LastPaymentSum = ((Bill)item).Payments.OrderByDescending(payment => payment.ID).FirstOrDefault().Sum });
}
Is it possible to avoid repeating the ((Bill)item).Payments.OrderByDescending(payment => payment.ID).FirstOrDefault() part 3 times? I tried turning it into a method and into a delegate - the code compiled in both cases, but produced an exception at runtime.
You can use the let contstruct as follows:
val = from item in val
let lastPayment = ((Bill)item).Payments
.OrderByDescending(payment => payment.ID)
.FirstOrDefault()
select new SimpleBill
{
lastPayment.CTime,
//Rest of fields
}
However, as you may noticed this uses the LINQ Query syntax vs. Method syntax. IIRC let is only available in the former.