I'm inserting a record in my PostgresSQL table passing DBNull.Value for a timestamp without time zone field using a NpgsqlParameter as below:
ncmd.Parameters.Add(new NpgsqlParameter(":EndDate", NpgsqlDbType.Timestamp));
DateTime? dtval = sr.GetDateTime("EndDate");
ncmd.Parameters["EndDate"].IsNullable = true;
if (dtval.HasValue)
ncmd.Parameters["EndDate"].Value = dtval;
else
ncmd.Parameters["EndDate"].Value = DBNull.Value;
When I try to select only those records with null values for the field I use "Select * From "EVAL" Where "EndDate" IS NULL" but nothing is returned. When I read the table data in the pgAdmin I see the value "-infinity" in the field.
Please, could somebody tell me how to pass null values for a NpgsqlParameter?
Thanks in advance,
Danilo da Silva
Sorry, I've found my error. When I read the data to be inserted from a datareader, I was getting a default value for the DateTime field when it is null and so I was inserting default(DateTime) not DBNull.Value. Now I'm testing dtval.HasValue && dtval != default(DateTime) and all goes right. Thanks.
Related
I am using the Postgres Package (On the pub.dev site) to UPDATE records in a very simple database. It has two fields: a Text field prime key named number, and a Date field named date_of_birth.
If the date_of_birth is a valid DateTime string then all is well (as can be seen from the code below). But if date_of_birth is unknown (so I set to null) the UPDATE fails:
import 'package:postgres/postgres.dart';
void main() async {
final conn = PostgreSQLConnection(
'localhost',
XXXXX,
'XXXXX',
username: 'XXXXX',
password: 'XXXXX',
);
await conn.open();
DateTime dob = DateTime.now();
var results;
results = await conn.query('''
UPDATE account_details
SET date_of_birth = '$dob'
WHERE number = '123123'
''');
await conn.close();
}
If I set:
dob = null;
The program fails with the error:
Unhandled exception:
PostgreSQLSeverity.error 22007: invalid input syntax for type date: "null"
So I need to include a check on the dob field and the program now looks like this:
DateTime dob = DateTime.now();
dob = null;
var results;
if (dob == null) {
results = await conn.query('''
UPDATE account_details
SET date_of_birth = null
WHERE number = '123123'
''');
} else {
results = await conn.query('''
UPDATE account_details
SET date_of_birth = '$dob'
WHERE number = '123123'
''');
}
That works fine for my simple database, but in my real App. I have a number of date fields in one table. So I have to do a check for each possible combination of those date values - writing a code block for each!
Can anyone tell me how I can UPDATE both null and a valid date using a single statement please?
You are quoting the query parameters yourself. NEVER do this. In addition to the sort of problem you have just seen it also leaves you open to a trivial SQL injection attack.
The library you are using will have some way of putting placeholders into the query text and passing variables when executing the query. Use that.
I'm new to Laravel and I'm trying to retrieve the id value of a selected row using query builder but it's not working. I've tried it in many ways according to the Laravel documentation and I still have a problem. I think it's related to the use of a variable but I don't know how to fix it.
public function submit_idea(Request $request)
{
$key=$request->input('key');
$workshop_id= DB::table('workshops')->where('autokey',$key)->value('id');
$id = auth()->User()->id;
$idea=new Idea;
$idea->title=$request->input('title');
$idea->description=$request->input('description');
$idea->user_id=$id;
$idea->workshop_id=$workshop_id;
$idea->save();
return view('submit_idea');
}
the error i'm getting is:
SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'workshop_id' cannot be null (SQL: insert into ideas (title, description, user_id, workshop_id) values (ppp, iiuu, 7, ?))
Can anyone help me, please?
Change:
$workshop_id = DB::table('workshops')->where('autokey',$key)->value('id');
To:
$workshop_id = DB::table('workshops')->select('id')->where('autokey',$key)->first();
By the way, the errors means that the workshop_id can't be null. If it can be null, be sure to add nullable() to the column in your migration file.
You can also working with
$workshopId = DB::table('workshops')->where('autokey', $key)->first()->pluck('name');
echo $workshopId;
In Go, I am unmarshalling/decoding JSON into a struct with an ID field of type int. Then I try to insert this struct into a PostgreSQL database using go-pg with the ID column as the primary key (which has a not-null constraint). The first entry has a 0 as its ID. In the Postgres documentation, it states that 0 is ok as a value of a primary key. However, I keep getting an error message:
"ERROR #23502 null value in column "number" violates not-null constraint".
It looks like the 0 turns into a Go "zero value" when it is unmarshalled into the int value. Then it is inserted as null value into Postgres. Any tips on how I might be able to avoid this would be greatly appreciated.
type Account struct {
Number int `sql:"type:smallint, pk"`
Name string
}
[...]
account := Account{}
err := json.NewDecoder(r.Body).Decode(&account)
[...]
insertErr := pgLayer.db.Insert(&account)
if insertErr != nil {
log.Printf("Error while inserting new item")
return "n/a", insertErr
}
While it's not immediately obvious with go-pg you can use the struct tag sql:",notnull" to show that Go empty values ("", 0, [] etc.) are allowed and should not be treated as SQL NULL.
You can see it in the Features list.
In your case I would change this to:
type Account struct {
Number int `sql:"type:smallint,pk,notnull"`
Name string
}
I think the easiest solution to your problem is to make your ID column of type SERIAL and let Postgres deal with setting and auto-incrementing the value for you. If you need the value within your application directly after inserting it, you can always use a RETURNING psql clause, like such:
INSERT INTO shows(
user_id, name, description, created, modified
) VALUES(
:user_id, :name, :created, :modified
) RETURNING id;
And capture the response within your code.
I am in scenerio where I need to inset a dateTime value in the database using the EF 4.1.
DateColumn in database in Nullable.
While creating the entity i am filling it as,
DTCLOSE = referenceProblemLog.DateClosed.HasValue ?
referenceProblemLog.DateClosed.Value.ToFeedFormatString() :
System.DBNull.Value.ToString(),
where ToFeedFormatString is an extension method.
Now problem i observed is, if I have a proper value then it is inserted correctly but
when i dont have a proper date value, i want to insert NULL in database column. However EF is saving column with Empty string
I tried to change the StoreGeneratedPattern for the field to "Identity" but problem with it is, I cant assign value to DTCLose field.
How can i have both the things?
1. EF should insert NULL in database when proper value is not there
2. proper value otherwise
Please help
Thanks
Anup
This is wrong System.DBNull.Value.ToString() because at the end you will have string object, ToString() never returns null.
You have to set DTCLOSE = null
Also, with EF you don't have to use DBNull, you just define nullable property and set it null
You Can use this :
Nullable<DateTime> date=null;
var entity = new Model()
{
GoDate = date
};
DataContext.Models.Add(entity);
DataContext.SaveChanges();
I'm trying to create a query that pulls information about sellers from my database, but only if their store has launched in the last 3 days. The easiest way I can think of to calculate the date for the query is using a new DateTime() object. When I output my code to test it, it's in the proper string for MySQL to query it with, but whenever I try to bind the variable, I get an error. I'm using Zend_Db to query, (PDO adapter)
action:
public function indexAction()
{
$dateMod = new DateTime();
$dateMod->modify('-2 days');
$dateMod->format('Y-m-d H:i:s');
// get sellers initialized in last 3 days
$sellerTable = new Application_Model_DbTable_Sellers();
$select = $sellerTable->select()->setIntegrityCheck(false);
$select->from(array('s' => 'seller'),array('sellerID', 'businessName'));
// select firstName, lastName, picture from user table, and businessName and sellerID from seller table.
$select->join(array('u' => 'user'), 's.userID = u.userID', array('firstName', 'lastName', 'picture'));
$select->where('s.active = 1 AND s.contentApproval = 1 AND s.paymentApproval = 1 AND s.featured = 1');
$select->where('s.launchDate > ?', $dateMod);
$select->order('s.launchDate DESC');
$newSellers = $sellerTable->fetchAll($select);
When I assign $dateMod to the view, it outputs the correct Y-m-d H:i:s format. But when I plug it into the query, I get the following error:
Message: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') ORDER BY `b`.`launchDate` DESC' at line 2
If I hardcode a value into dateMod in the mysql timestamp format, the query works fine. How can I access just the string value of the timestamp in the DateTime object? getTimestamp returns a unix formatted timestamp, even after assigning a format.
The format() function returns the formatted date, so you need to assign that to a variable for use in the query:
$dateFormatted = $dateMod->format('Y-m-d H:i:s');
$select->where('s.launchDate > ?', $dateFormatted);