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POHow to retrieve SQL Query (last record id) + Execute it in ASP.NET & concatenate (append/prepend) it with a String
 

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  1. POHow to retrieve SQL Query (last record id) + Execute it in ASP.NET & concatenate (append/prepend) it with a String
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    <p>I'm trying to retrieve the last ID, in a table, using SQL query and then append the result together with a TextBox value (which is a String):</p> <pre class="lang-vb prettyprint-override"><code>Dim searchforID = New OleDbCommand("select ID from [table1] where ID = (select max(id) from [table1])", con) Dim variable1 = searchforID + TextBox1.Text </code></pre> <p>But it throws this error:</p> <blockquote> <p>Compiler Error Message: BC30452: Operator '+' is not defined for types 'System.Data.OleDb.OleDbCommand' and 'String'.</p> </blockquote> <p><BR><h2>Trying to fix it</h2> -- So i tried to convert the returned record ID like this:</p> <pre class="lang-vb prettyprint-override"><code>Dim variable1 = Convert.ToString(searchforID) + TextBox1.Text </code></pre> <p>There is no error now but unfortunately the result returned is "System.Data.OleDb.OleDb" + the textbox value, as this example:<BR> <strong>System.Data.OleDb.OleDbtest</strong></p> <p>-- I too thought to convert the returned record ID to integer throws an error:<br></p> <blockquote> <p>Exception Details: System.InvalidCastException: Unable to cast object of type 'System.Data.OleDb.OleDbCommand' to type 'System.IConvertible'.</p> </blockquote> <h3>So why does retrieving the last record ID fail? Might my SQL query be false?</h3> <p>Thank you.</p> <hr> <h1>So straight forward solution for problem if someone may find it useful:</h1> <pre class="lang-asp prettyprint-override"><code>Dim searchforID = New OleDbCommand("select MAX(ID) from [table1]", con) Dim variable1 = searchforID.ExecuteScalar() &amp; TextBox1.Text </code></pre> <p>Also the answers and comments below have useful information.</p>
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    1. COyou cant do like this. You need to return Id from table using execute scalar command
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    2. CO`searchforID` is an `OleDbCommand` which you must execute against the database. You must retrieve the _result_ of the query, not the query itself.
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      1. POHow to retrieve SQL Query (last record id) + Execute it in ASP.NET & concatenate (append/prepend) it with a String
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    3. CO@AshReva You hit the point. I understand that ExecuteScalar is good for a one result, do you know if there are other methods than ExecuteScalar that do the same job too?
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