Open(); My Sql Command command = new My Sql Command( "SET @param1=11; CALL testproc(@param1); SELECT @param1", my Conn); using (IData Reader reader = command. Close(); Dim my Conn As My Sql Connection = New My Sql Connection( _ "user id=root;database=demobase;host=localhost;password=root") my Conn. Write Line("@param1 = " & reader(0)) End If reader. Thus performance mostly depends on how fast these additional round trips are performed.
Open() Dim command As My Sql Command = New My Sql Command( _ "SET @param1=11; CALL d.testproc(@param1); SELECT @param1", my Conn) Dim reader As IData Reader = command. To optimize multiple execution of a query you can manually call you can manually call the My Sql Command.
Consider the following CREATE statement: The procedure takes input parameter, multiplies it by two, and stores outcome in the out parameter.
To retrieve value of out parameter declare temporary server variable and then query its value as follows: My Sql Connection my Conn = new My Sql Connection( "user id=root;database=demobase;host=localhost;password=root"); my Conn. Value = "SALES" Dim my Reader As My Sql Data Reader = my Command.
If name of a parameter is suitable for the description of stored procedure, parameter is preserved in the collection, otherwise it is lost. Command Text property and Parameters collection are unchanged all subsequent invocations of Prepare or Execute methods will not result in recreation of parameters. Read Line() End Sub The following example shows how to get a stored function to work. Open() 'Set up my Command to reference stored procedure 'Add Emp' Dim my Command As My Sql Command = New My Sql Command("Add Emp", my Conn) my Command.
For example, consider you had a stored procedure that accepts two arguments, deptno and dname, and then changed My Sql Command. We will not use parameters autosynchronisation here.
dot Connect for My SQL enhances SQL handling capabilities with usage of parameters in SQL queries. Omitted parameters will be created and assigned DBNull value. Here is how source code for this procedure may look: CREATE PROCEDURE `Add Emp`(Emp Name CHAR(20), Salary INT) BEGIN DECLARE e_No INT; DECLARE e_Name CHAR(20) DEFAULT 'Unnamed'; DECLARE e_Sal INT DEFAULT 1100; IF Emp Name IS NOT NULL THEN SET e_Name = Emp Name; END IF; IF Salary IS NOT NULL THEN SET e_Sal = Salary; END IF; SELECT Max(Emp No) INTO e_No FROM emp; INSERT INTO emp (Emp No, EName, Sal, Hire Date) VALUES (e_No 10, e_Name, e_Sal, Cur Date()); END We will invoke this procedure and pass it single parameter - Emp Name.
You can make execution of a query or stored procedure very flexible using several simple techniques. The following query My Sql Command my Sql Command1; ... Command Text = "INSERT INTO dept (deptno, dname, loc) VALUES (? You can set up required parameters in any order you like. Since Parameter Check is true, the second parameter will be created in the moment of calling Execute Non Query method.
If parameters are added to the command collection in the order that is different from the function parameters order in database, it is necessary to describe the command by setting My Sql Command. It determines next suitable Emp No, pastes current date, and checks for input parameters.
Add("loc", "NEW YORK") My SQL server variables are also denoted using '@' symbol.
Parameter's name must match exactly name of procedure's argument. Input 'Create placeholder for return value Dim my Ret Param As My Sql Parameter = New My Sql Parameter() my Ret Param. You do not have to take care of creation order and there's no need to create parameters that are intended to have NULL value. Parameter Check = True 'Create input parameter and assign a value Dim my In Param As My Sql Parameter = New My Sql Parameter my In Param.
However the Return Value parameter needs not to have any specific name. Put another words, if we need to add an employee with default name but with specific salary, we can create single argument with Parameter Name set to "Salary".
In synchronization mode first call to My Sql Command. Execute methods leads to recreation of all argument parameters. Sub Call Proc() 'Establish connection Dim my Conn As My Sql Connection = New My Sql Connection( _ "user id=root;database=demobase;host=localhost;password=root") my Conn.