I have a table in Lightswitch to which I have added a computed column named 'FullName'. In the method for that field..I have written
FullName = this.EmployeeFirstName + " " + this.EmployeeMiddleName + " " + this.EmployeeLastName;
but C# is giving me an error 'Property or Indexer cannot be assigned to -- it is read only'
Can anyone please help me with this one??
Thanks in advance
To set the value of the computed property, you set the value of the "result" parameter that is passed into the FullName_Compute method.
partial void FullName_Compute(ref string result)
{
result = this.EmployeeFirstName + " " + this.EmployeeMiddleName + " " + this.EmployeeLastName;
}
How to: Add a Computed Field in a LightSwitch Database
Related
I have the following code:
private void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
string age = dataGridView1.Rows[e.RowIndex].Cells["dataGridViewTextBoxColumn43"].Value.ToString();
dataGridView1.Rows[e.RowIndex].Cells["dataGridViewTextBoxColumn43"].Value = (age == "1") ? "Муж" : "Жен";
}
When I run program it gives fatal message:
In database field gender is as integer type. This value should be added to column name: dataGridViewTextBoxColumn43.
Query to database:
public DataTable select(SQLiteDatabase db)
{
return db.GetDataTable("SELECT " +
"Pacients.id, " +
"unique_code," +
"status_pass, " +
"payment, " +
"profession," +
"office_address, " +
"factory_name, " +
"factory_edrpou, " +
"factory_departament," +
"name, " +
"secondname, " +
"lastname, " +
"datebirth, " +
"taxcode, " +
"gender, " +
"Pacients.created_at, " +
"file, " +
"PacientsOrder.kind_work, " +
"PacientsOrder.status " +
"FROM Pacients LEFT JOIN PacientsOrder ON PacientsOrder.pacient_id = Pacients.id LEFT JOIN Transactions ON Transactions.pacient_id = Pacients.id ORDER BY Pacients.id DESC");
}
If the column ValueType is numeric, you can change the number format in the designer to Муж;;Жен
dataGridView1.Columns["dataGridViewTextBoxColumn43"].DefaultCellStyle.Format = "Муж;;Жен";
If I understand you correctly, you are trying to add a text value to a column, based on an integer value which is currently in the same column (ie you are switching column value types)?
Please do not do it this way, as it will not work for several reasons. Apart from your error, the most important being that this event is fired when you set the DataSource of your DataGridView for every row created, but the e.RowIndex is not always the RowIndex of the new row. For full details read here.
Normally you would only use RowsAdded when the user has inserted a new row from the interface.
What you should do instead, is to provide this conversion in your SELECT statement that reads the data from the database. That way you do not need to convert the data when it hits the DataGridView. So your SELECT needs to be something like:
SELECT .... CASE WHEN gender = 1 THEN 'МУЖ' ELSE 'ЖЕН' END AS gender ...
Edit
Try changing your SELECT statement so it reads as follows:
public DataTable select(SQLiteDatabase db) {
return db.GetDataTable("SELECT " +
"Pacients.id, " +
"unique_code," +
"status_pass, " +
"payment, " +
"profession," +
"office_address, " +
"factory_name, " +
"factory_edrpou, " +
"factory_departament," +
"name, " +
"secondname, " +
"lastname, " +
"datebirth, " +
"taxcode, " +
"CASE WHEN gender = 1 THEN 'МУЖ' ELSE 'ЖЕН' END AS gender, " +
"Pacients.created_at, " +
"file, " +
"PacientsOrder.kind_work, " +
"PacientsOrder.status " +
"FROM Pacients LEFT JOIN PacientsOrder ON PacientsOrder.pacient_id = Pacients.id LEFT JOIN Transactions ON Transactions.pacient_id = Pacients.id ORDER BY Pacients.id DESC");
}
Now you can get rid of the add rows event completely, as the database has done the work for you, before it hits the datagridview.
The problem was the folowing, it is obvios, but not clear at once:
The gender field is stored in database as integer type.
So, when I bind DataGridView with existing database table It allocates memory for building table with defination all properties of table, including cell types.
Therefore, when it happends at the first time, the datagridview expects to get integer data type as value, but I modify the value cell to string value and try to overwrite value.
It involkes an fatal error.
Solution was to change all data types that have got integer to string type.
Thanks for answers, it will be accepted!
Error Code : 1 (SQLITE_ERROR)
Caused By : SQL(query) error or missing database.
(near "=": syntax error (code 1): , while compiling: DELETE FROM notesWHEREid='1')
This is the error i am getting:
This is the part of my database handler that is the source of this error:
public void deleteNote(String id) {
SQLiteDatabase db = this.getWritableDatabase();
String deleteQuery="DELETE FROM " + DatabaseValues.TABLE_NOTES + "WHERE" + DatabaseValues.NOTES_ID + "= '" + id + "'";
db.execSQL(deleteQuery);
db.close();
}
If you are using C# 6.0, using interpolated strings makes life much easier for strings concatenation, avoiding such silly errors:
String deleteQuery= $"DELETE FROM {DatabaseValues.TABLE_NOTES} WHERE {DatabaseValues.NOTES_ID} = id";
Note: $ operator is available in C# 6.0. Also you should take a look into how to build parameterized queries because passing parameters like this can expose you to SQL injection.
Change your following statement:
String deleteQuery="DELETE FROM " + DatabaseValues.TABLE_NOTES + "WHERE" + DatabaseValues.NOTES_ID + "= '" + id + "'";
to
String deleteQuery= "DELETE FROM " + DatabaseValues.TABLE_NOTES + " WHERE " + DatabaseValues.NOTES_ID + " = '" + id + "'";
Actually you are combining the table name with where clause. You need to add a space before and after WHERE Clause like " Where "
Hope it helps.
So I have the following code :
public static void WriteToDatabase(string sql,string value,int Amount, string URL)
{
int times = int.Parse(((dr)[dt.Columns[1]]).ToString()) + Amount;
sql = "UPDATE Words "+
" SET Amount = " + times +
" WHERE Word = " + value +
" AND Website = " + URL + ";";
myAdp = new OleDbDataAdapter();
myAdp.InsertCommand = new OleDbCommand(sql, myConn);
myAdp.InsertCommand.ExecuteNonQuery();
}
Which supposed to update a value in a pre-made Microsoft Access 2007 file,
and whenever I run the code they following OleDb exception occurs :
An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll ,
Syntax error missing operator in query expression : 'Word = meta AND Website = http://www.twitch.tv/directory'."
"
So I've searched the web for common errors that could happen, and I couldn't find any,
I'll be glad if someone can find the mistake in the sql.
Thanks.
You absolutely should be using parameterized queries for this. That is the right way to pass values in.
Your problem is that your query is missing single quotes:
"UPDATE Words "+
" SET Amount = " + times +
" WHERE Word = '" + value + "'" +
" AND Website = '" + URL + "'"
But let me re-emphasize that although this should work, you should fix the code so it uses parameters
Assuming the Word field is a varchar, you have forgotten the necessary single quotes around the variable. " WHERE Word = '" + value + "'"
I am making a query involving 2 tables in C#. The query works fine when I input information into all the combo boxes. But when I try to make query with some empty combo boxes, it returns nothing.
I get that it is cos the string ends up having "" in the query which makes it invalid. Is there anyway I could restructure my query to make it possible to make queries with missing entries or even a missing secondary table? Thanks for advice.
The following works when I fill up all fields and make the query:
If I fill up only paritial fields as follows, it won't work:
My query String:
string query = #"SELECT Agents." + comboq1.Text + ", Agents." + comboq2.Text + ", Agents." + comboq3.Text + ", Agents." + comboq4.Text + ", "
+ secondaryTable.Text + "." + stCombo1.Text + ", " + secondaryTable.Text + "." + stCombo2.Text
+ " FROM Agents INNER JOIN " + secondaryTable.Text + " ON Agents.Dept_ID" + "="
+ secondaryTable.Text + ".Dept_ID";
string agentsValue = string.empty;
if (!comboq1.Text.equals(string.empty))
{ agentsValue = "Agents."+comboq1.text; }
if (!agentsValue.equals(string.empty))
{ agentsValue +=","; }
if (!comboq2.Text.equals(string.empty))
{
if (agentsValue.equals(string.empty))
{ agentsValue = "Agents."+comboq2.text; }
else
{ agentsValue += "Agents."+comboq2.text; }
}
please follow the above code for rest of the combo boxes and while adding the value of the second combo box add a comma in between the values. After building the string in this format you can then append it to your query and now when you execute the query you should not find any kind of errors.
Hope this helps
I would suggest that you use a separate string by checking that if any combo box does not provide any value then omit that combo box value from the string and then append the final string to you query which will not cause any problem.
there are other question (at least 2 I've seen them) similar to this but I'm not able to solve this using them.
Now the problem: I've 3 table from which I need to select 4 columns only. I'm using InnerJoin and it is working perfectly. Problem starts when I add a Where to this Select. I've a column named "Name" in two tables. If I add simply the
.Where("Name").Like("A%")
It says "... ambiguous column name.."
If I use fully qualified column name (with table prefixed to column name) it says must declare parameter #TABLE_NAME
SqlQuery sq = new Select(Tables.TableOne + "." + TableOne.Columns.MemberId +
" AS MemberId",
Tables.TableTwo + "." + TableTwo.Columns.Name + " AS MemberName",
Tables.TableOne + "." + TableOne.Columns.ExpiryOn + " AS MembershipExpiresOn",
Tables.TableFour + "." + TableFour.Columns.Name + " AS Country")
.From(DAL.Tables.TableOne)
.InnerJoin(Tables.TableTwo)
.InnerJoin(Tables.TableThree)
.InnerJoin(Tables.TableFour, TableFour.Columns.CountryCode,
Tables.TableThree, TableThree.Columns.CountryOfBirth).
sq.Where(Tables.TableTwo + "." + TableTwo.Columns.Name).Like("A%");
I've tried to pass hard-coded string also but nothing works!
If you pass in the column object to the Where statement SubSonic will use it's fully qualified name instead of building a string. You can find the column on the object as a static property, so in this case if you have an object called "TableOne" you can use "TableOne.NameColumn" and pass that into the Where():
...
sq.Where(TableTwo.NameColumn).Like("A%");
Does the following query work, I'm assuming you're using 2.2:
SqlQuery sq = new Select(TableOne.Columns.MemberId + " AS MemberId",
TableTwo.Columns.Name + " AS MemberName",
TableOne.Columns.ExpiryOn + " AS MembershipExpiresOn",
TableFour.Columns.Name + " AS Country")
.From(TableOne.Schema)
.InnerJoin(TableTwo.Schema)
.InnerJoin(TableThree.Schema)
.InnerJoin(TableFour.Schema)
.Where(TableTwo.Columns.Name).Like("A%");
I haven't used it ever,
but have your tried to change your last line to:
sq.WhereExpression(Tables.TableTwo + "." + TableTwo.Columns.Name + " LIKE 'A%');