How do I insert value from C# text boxes to postgresql?

Question

0.00/5 (No votes)

See more:

I have a database in postgresql, and I have defined a tables named customer with 3 columns:

1. ID => Type: int
2. Name => Type: varchar(50)
3. Email => Type: varchar(50)

What I have tried:

I have defined a sequence named customer_id to fill ID automatically so I use the following code to insert data into the table:

NpgsqlCommand cmd1 = new NpgsqlCommand("insert into customer values (nextval('customer_id'), + '" + textbox1.Text + "' , '" + textBox2.Text + "');", con1);
cmd1.ExecuteNonQuery();

But I get the following exception when I try to add these data:
Name: Naser
Email: naser@yahoo.com

22P02: invalid input syntax for type double precision: "Naser"

Posted 29-Dec-19 16:54pm

Naser Sadeghi

Updated 29-Dec-19 20:31pm

RickZeeland

v2

Add a Solution

Comments

RickZeeland 30-Dec-19 2:39am

You can test your SQL insert query in pgAdmin, my guess is that you need something like:
insert into customer (id, name, email) values (nextval('customer_id'), 'Naser', 'naser@yahoo.com';

Naser Sadeghi 30-Dec-19 10:41am

I tested the same query in pgAdmin and it works well. The problem shows up when I want to insert data from C# windows form application.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Patrice T · Answer 1 · 2019-12-29T17:05:00

C#

NpgsqlCommand cmd1 = new NpgsqlCommand("insert into customer values (nextval('customer_id'), + '" + textbox1.Text + "' , '" + textBox2.Text + "');", con1);

Not necessary a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
SQL Injection Prevention Cheat Sheet - OWASP[^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[^]