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Problem with Syntax Error in SQL statement

I am trying to get a specific single value from an Access Database using C#.
For some reason what I am asking for is giving me an exception of
Syntax error in FROM clause
and I cant work out why.
I have tried running the SQL directly in Access itself and it works fine and gives me back the results I want, but I have no idea why its not working in my program.
ProbID is a number field as far as Access describes it and CorrDetails is a memo field.
For simplicity i have set the SQL to look for a specific value (137) but once i have the code working i will make it paramiterised.
Any ideas?
string corrAct;
OleDbConnection dbConnection;
dbConnection = new OleDbConnection(vDbString);
string sqlString = "SELECT CorrDetails FROM Action WHERE ProbID=137";
OleDbCommand command = new OleDbCommand(sqlString, dbConnection);
using (dbConnection)
{
MessageBox.Show(sqlString);
dbConnection.Open();
corrAct = (String)command.ExecuteScalar();
rtfCorrectiveAction.Text = Convert.ToString(corrAct);
dbConnection.Close();
}

Action is a reserved word in MS Access.
Wrap it with []:
string sqlString = "SELECT CorrDetails FROM [Action] WHERE ProbID=137";

The problem is you havent taken into account keywords in SQL. https://learn.microsoft.com/en-us/sql/odbc/reference/appendixes/reserved-keywords?view=sql-server-ver15
Action is a keyword so should not be used really in another context, to use them put [] round them some it becomes
select stuff from [Action] where stuff=true

.Net C# Connector/NET Query with parameters not working

I'm making a login in asp.net. The query to fetch a user from the database always returns an empty set even when there should be a row back.
I'm using Connector/NET with c#
I have the query to get the user by email declared like this:
select * from users where email = '#email';
In the database I have two rows: test1#example.com and test2#example.com
My code looks like this:
UserByEmail is a string with the query as seen above.
MySqlCommand query = new MySqlCommand(UserByEmail, db);
db.Open();
query.Parameters.AddWithValue("#email", email);
MySqlDataReader reader = query.ExecuteReader();
if(reader.Read()){
/* Do stuff */
}
db.Close();
When I run it like this with any of the test cases, the property reader.HasRows always returns false. I've changed the query directly to:
- select * from users;
- select * from users where email = 'test1#example.com';
And for both of them, there are rows back. So the problem is when I use the parameter #email and the query.Parameters.AddWithValue("#email", email);.
Any idea what's happening here? I've looked for this problem and have find nothing. The code is almost the same as in the doc's example ( Connector/NET Tutorials: Parameters )

Remove ' from sides of '#email' as addwith value adds it where necessary:
string query = "select * from users where email = #email"
By the way, its better to use Parameters.Add(), instead of Parameters.AddWithValue():
command.Parameters.Add("#email", SqlDbType.VarChar).Value = email;

MySql Last Insert ID, Connector .net

I'm using the MySql Connector .net, and I need to get the insert id generated by the last query. Now, I assume the return value of MySqlHelper.ExecuteNonQuery should be the last insert id, but it just returns 1.
The code I'm using is:
int insertID = MySqlHelper.ExecuteNonQuery(Global.ConnectionString,
"INSERT INTO test SET var = #var", paramArray);
However insertID is always 1. I tried creating a MySql connection and opening/closing manually which resulted in the same behaviour

Just use LastInsertedId field
MySqlCommand dbcmd = _conn.CreateCommand();
dbcmd.CommandText = sqlCommandString;
dbcmd.ExecuteNonQuery();
long imageId = dbcmd.LastInsertedId;

1 is the no of records effected by the query here only one row is inserted so 1 returns
for getting id of the inserted row you must use scope_identity() in sqlserver and LAST_INSERT_ID() in MySql

Try to use this query to get last inserted id -
SELECT LAST_INSERT_ID();
Then, run DbCommand.ExecuteReader method to get IDataReader -
command.CommandText = "SELECT LAST_INSERT_ID()";
IDataReader reader = command.ExecuteReader();
...and get information from the reader -
if (reader != null && reader.Read())
long id = reader.GetInt64(0);
...do not forget to close the reader;-)

I had the same problem, and after some testing, I found out that the problem seem to be the connection method; you are using a connection string.
This is of course to make use of the automatic connection pool reuse, but in this case it gave me trouble.
The final solution for me is to create a new connection, execute the insert query, and then execute the last_insert_id(). On the same connection.
Without using the same connection, last_insert_id() might return anything, I don't know why, but guess it looses track of things as it can be different connections.
Example:
MySqlConnection connection = new MySqlConnection(ConnectionString);
connection.Open();
int res = MySqlHelper.ExecuteNonQuery(
connection,
"INSERT INTO games (col1,col2) VALUES (1,2);");
object ores = MySqlHelper.ExecuteScalar(
connection,
"SELECT LAST_INSERT_ID();");
if (ores != null)
{
// Odd, I got ulong here.
ulong qkwl = (ulong)ores;
int Id = (int)qkwl;
}
I hope this helps someone!

I know this is an old post, but I have been facing the same issue as Snorvarg. Using MySqlHelper, and using a connection string instead of a Connection object (to allow MySqlHelper to use connection pooling), SELECT LAST_INSERT_ID() would often give me the ID of the previous query that was executed, or other times it would return zero. I would then have to call SELECT LAST_INSERT_ID() a second time to get the correct ID.
My solution was to encapsulate everything between the query that's being executed, and the calling of SELECT LAST_INSERT_ID() in a TransactionScope. This forces MySqlHelper to stick to one connection instead of opening two separate connections.
So:
string sql = "INSERT INTO games (col1,col2) VALUES (1,2);");
string connectionString = "some connection string";
using (TransactionScope scope = new TransactionScope)
{
int rowsAffected = MySqlHelper.ExecuteNonQuery(connectionString, sql);
object id = MySqlHelper.ExecuteScalar(connectionString, "SELECT LAST_INSERT_ID();");
scope.Complete();
}

try below working solution in repository .
string query = $"INSERT INTO `users`(`lastname`, `firstname`, `email`, `createdate`, `isdeleted`) " +
$"VALUES ('{userEntity.LastName}','{userEntity.FirstName}','{userEntity.Email}','{userEntity.CreateDate}',{userEntity.IsDeleted});" +
$"SELECT LAST_INSERT_ID();";
var res= _db.ExecuteScalar(query);
return (int)(UInt64)res;

Proper SQL query command with SQL Compact is failing

I've got a function that stores temporary information generated for every user authenticated in the system. This 'session ID' is a string stored in a Sessions table, along the original ID of the user which authenticated and was given said session identifier.
The function to remove/deauthenticate/invalidate an existing session first checks if the user exists through another method implemented as follows:
int userId = 0;
SqlCeCommand cmd = new SqlCeCommand();
SqlCeParameterCollection sqlParams = cmd.Parameters;
sqlParams.AddWithValue("#User", userName);
cmd.Connection = this.conn;
cmd.CommandText = "SELECT Id FROM Users WHERE (Username = #User)";
userId = (int) cmd.ExecuteScalar()
cmd.Dispose();
Afterwards it tries to find an existing session for that user, which is to be removed (via a different method again):
SqlCeCommand cmd = new SqlCeCommand();
SqlCeParameterCollection sqlParams = cmd.Parameters;
sqlParams.AddWithValue("#SID", mysession);
sqlParams.AddWithValue("#UID", myuserid);
cmd.Connection = this.Connection;
cmd.CommandText = "SELECT Id FROM UserSessions WHERE (SessionID = #SID) AND (User_Id = #UID)";
int foo = cmd.ExecuteNonQuery();
...which fails. No exception is raised unfortunately. So I added an insecure equivalent using a non parametrized query string:
cmd.CommandText = String.Format("SELECT Id FROM UserSessions WHERE (SessionID = '{0}') AND (User_Id = {1})", mysession, myuserid);
cmd.Prepare();
int bar = cmd.ExecuteNonQuery();
Added a breakpoint, paused, copy pasted the query into the Visual Studio Query tool and voila, it indeed worked. But after continuing, that query in the code failed as well. I'm unable to find the culprit of this annoying issue since no exception is raised and everything seems correct. The data exists, the parameters are provided in proper types (string and int) and I'm out of things to check. The connection is open and so forth.
Any clues from anyone around? Thanks!
Update: Mea culpa, missed the fact that the function used ExecuteScalar until I modified it for testing. It does use ExecuteScalar and returns null, just in case.

You're using ExecuteNonQuery:
int foo = cmd.ExecuteNonQuery();
... but you're clearly trying to execute a query (a SELECT)! Use ExecuteScalar again, as you did in the first code, or ExecuteReader and look through the results appropriately. If you stick with ExecuteScalar, you should first check whether the result is null to indicate no results.
ExecuteNonQuery returns the number of rows affected by an UPDATE/INSERT/DELETE command - which is what it's intended for. I suspect it's returning -1 for you, as documented:
For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. When a trigger exists on a table being inserted or updated, the return value includes the number of rows affected by both the insert or update operation and the number of rows affected by the trigger or triggers. For all other types of statements, the return value is -1. If a rollback occurs, the return value is also -1.
(Emphasis mine.)

Use set [] to avoid ambiguity with database keyword.
cmd.CommandText = "SELECT [Id] FROM [Users] WHERE ([Username] = #User)";
and use ExecuteScalar() or ExecureReader() method when working with SELECT statements.

Problem while printing a maximum value obtained from the database

I am trying to find the MAX number from a database field,The query below returns me the maximum value if i run it in SQL Enterprise Manager but i am not able to print the value in numbwe. Please help me to print the MAX value obtained from the database.
SqlConnection MyConnection = new SqlConnection("Data Source=localhost;Initial Catalog=hcgoa;User Id=sa;Password=;");
SqlCommand MyCmd = new SqlCommand("SELECT MAX([no]) AS Expr1 FROM jmain", MyConnection);
MyConnection.Open();
SqlDataReader myReader = MyCmd.ExecuteReader();
if (myReader.Read())
{
string numbwe = myReader["no"].ToString();
Response.Write("Max no. is : " + numbwe);
}

You need to use Expr1 as the key, not no.
That's because you're doing:
SqlCommand MyCmd = new SqlCommand("SELECT MAX([no]) AS Expr1 ...
(note the AS clause) so the column is named Expr1. Hence:
string numbwe = myReader["Expr1"].ToString();
should do it.
Although, in fairness to those who come after you, Expr1 is not a very descriptive identifier. Consider the possibility of changing it to something like MaxNum (both in the select and the key, of course).

You should look at the ExecuteScalar() instead if you are going to return a single value.
MSDN: Use the ExecuteScalar method to
retrieve a single value (for example,
an aggregate value) from a database.
This requires less code than using the
ExecuteReader method, and then
performing the operations that you
need to generate the single value
using the data returned by a
SqlDataReader.

You're trying to print the value of a column that doesn't exist in the query result. Your query returns a column named Expr1, not a column named "no"
Change
string numbwe = myReader["no"].ToString();
to
string numbwe = myReader["Expr1"].ToString();

should be string numbwe = myReader["Expr1"].ToString();
as you are specifying your column name in sql statement Expr1
SELECT MAX([no]) AS Expr1