Vb.net | SQL how to select value from data_table column and get value

Question

1.00/5 (1 vote)

See more:

Hi Coders,

Could you help, I have SQL data_table(datagrid) and I need to get value from a single column(Hours).

SQL Data Table

ID	Name	Hours
1	Name1	8
2	Name2	9
3	Name3	8

Txt_Name.Text: Name1
Txt_BusinessDays.Txt = 20

Txt_Name.Text: Name2
Txt_BusinessDays.Txt = 21

Expected Output:

Txt_Name.Text: Name1
Txt_BusinessHours.Txt = 160

What I have tried:

Tried this code, but did not work.

VB

con.ConnectionString = "Server=.

\SQLEXPRESS; Database=test_Db; Integrated 

Security=True"
                    con.Open()
                    cmd.Connection = con
                    cmd.CommandText = 

"SELECT b_days FROM  hours_table WHERE 

(Name = '" & DataGridView1.Rows(i).Cells

(0).Value & "' )"
                    Dim lrd As 

SqlDataReader = cmd.ExecuteReader()

                    If lrd.HasRows Then
                        While lrd.Read
                            

Txt_BusinessHours.Text = lrd

("Hours").ToString()
                        End While
                    End If

Posted 16-Dec-19 23:38pm

jreypalars

Updated 30-Dec-19 12:10pm

Maciej Los

v2

Add a Solution

2 solutions

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)

OriginalGriff · Answer 1 · 2019-12-17T00:31:00

First off, specify the columns you need:

SQL

SELECT Name, Hours FROM hours_table WHERE ...

You'd also be better off not using Name as the "key" to select rows as it is likely to be non-unique: names repeat a lot, and the ID column is what should distinguish rows, not names.

But ... don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

codejet · Answer 2 · 2019-12-30T12:10:00

Solution 2

How about filtering using a dataview rowfilter Something from codeproject

Posted 30-Dec-19 12:10pm

codejet