How to correctly set parameters in a request?

Question

SQL

There is a connection to the database, the request is working, there is a table in that database, everything for connecting to the database and sending the request is configured correctly, as I understand it. But why can't I substitute the variable value into the query, what am I doing wrong?
added later:
I temporarily solved this problem like this: in the script I simply dynamically generate a request, I substitute all the parameters in it directly into the request text. That's how it worked.

private const string NotifyManagerTimestampName = "NotifyManagerTimestamp";
        private const string SqlNotifyManagerTimestamp = "SqlNotifyManagerTimestamp";

        private const string SqlNotifyManagerPattern = @"UPDATE DatetimeStamp SET STAMP = CAST({0} AS DATETIME2) WHERE NAME = 'SsisTestManager';";

        /// <summary>
        /// This method is called when this script task executes in the control flow.
        /// Before returning from this method, set the value of Dts.TaskResult to indicate success or failure.
        /// To open Help, press F1.
        /// </summary>
        public void Main()
        {
            try
            {
                DateTime now = DateTime.Now;
                string nowParam = "'" + now.Year + now.Month.ToString("00") + now.Day.ToString("00") + "'";
                string result = string.Format(SqlNotifyManagerPattern, nowParam);

                Dts.Variables[NotifyManagerTimestampName].Value = now;
                Dts.Variables[SqlNotifyManagerTimestamp].Value = result;
                
                Dts.TaskResult = (int)ScriptResults.Success;
            }
            catch (Exception)
            {
                Dts.TaskResult = (int)ScriptResults.Failure;
            }
        }

the end.
The query I use in the "Execute SQL Task"

UPDATE DatetimeStamp SET STAMP = CAST([NotifyManagerTimestamp] AS DATETIME2) 
WHERE NAME = 'SsisTestManager';

- Task Execute SQL task:
Data
validation started Data validation completed
[Execute SQL task] Error: Executing the query "UPDATE DatetimeStamp SET STAMP = CAST([NotifyManag..." failed with the following error: "Invalid column name 'NotifyManagerTimestamp'.". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly.
Task 'Execute SQL' task failed

Answer 1

1) Why write in []?
2) Please show how your SQL query is formed and called

Answer 2

The fact that you are making a request means the following:
For the STAMP field,
take the value from the [NotifyManagerTimestamp] field
Therefore, the error. They write to you about it: such a field was not found. If you want to use a variable, then it's like this: @NotifyManagerTimestamp