What is the return value of ExecuteScalar?

What is the return value of ExecuteScalar?

ExecuteScalar would simply return the value in the First Column of First Row of the output that your query returns. Return Value of ExecuteNonQuery is Int32. Return Value of ExecuteScalar is System. Object.

Can ExecuteScalar return null?

ExecuteScalar: If the first column of the first row in the result set is not found, a null reference (Nothing in Visual Basic) is returned. If the value in the database is null, the query returns DBNull. Value.

How do I check if ExecuteScalar is returning null values?

First you should ensure that your command object is not null. Then you should set the CommandText property of the command to your sql query. Finally you should store the return value in an object variable and check if it is null before using it: command = new OracleCommand(connection) command.

What does DBNull value return?

DBNull represents a nonexistent value returned from the database. In a database, for example, a column in a row of a table might not contain any data whatsoever. That is, the column is considered to not exist at all instead of merely not having a value. A DBNull object represents the nonexistent column.

What is the difference between ExecuteNonQuery () and ExecuteScalar ()?

ExecuteScalar() only returns the value from the first column of the first row of your query. ExecuteReader() returns an object that can iterate over the entire result set. ExecuteNonQuery() does not return data at all: only the number of rows affected by an insert, update, or delete.

What will ExecuteNonQuery return?

Although the ExecuteNonQuery returns no rows, any output parameters or return values mapped to parameters are populated with data. For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. For all other types of statements, the return value is -1.

Does ExecuteNonQuery return a value?

Is system DBNull value?

DbNull. Value , is a valid reference to an instance of System.

What is use of ExecuteScalar ()?

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.

Does ExecuteNonQuery close connection?

The connection’s current state is closed.

What is difference between ExecuteNonQuery and ExecuteQuery?

Moreover the executeQuery() is not used in . net but it is used in JAVA. ExecuteNonQuery: Executes Insert, Update, and Delete statements (DML statements) and returns the number of rows affected.

Why does executescalar not return null when there is no result?

Thats not true in this case. ExecuteScalar should return null if there are no results from the query, it will return DBNull.Value if there is a result, but its value is null.

When does executescalar return nothing in Visual Basic?

According to MSDN documentation for DbCommand.ExecuteScalar: If the first column of the first row in the result set is not found, a null reference (Nothing in Visual Basic) is returned. If the value in the database is null, the query returns DBNull.Value.

How to check return value of executescalar ( )?

Then you should set the CommandText property of the command to your sql query. Finally you should store the return value in an object variable and check if it is null before using it:

What does executescalar do in dbcommand.common?

When overridden in a derived class, executes the query and returns the first column of the first row in the result set returned by the query. All other columns and rows are ignored. public abstract object? ExecuteScalar (); The first column of the first row in the result set.