MySQL

This article briefly describes how to install MySQL locally and how to interact with a MySQL DB using a VIP (GUI) program.

Download and install MySQL
See http://www.mysql.com and http://dev.mysql.com/downloads/ Download the MySQL community Server

At the end of the installation you will automatically be prompted to configure the server, via the MySQL Server Instance Configuration Wizard. You can call this wizard at any time from the Windows Start-Programs-MySQL menu item.

Select all the defaults for the dialogs as presented by the wizard: it's probably best to use a non-blank password (e.g. "scott").

Check that the server is running as a Windows service (Control Panel - Performance and Maintenance - Administrative Tools - Services)

Also Download and install the MySQL ODBC Driver

See http://www.mysql.com/products/connector/odbc/

Create an ODBC Datasource
Go to Control Panel - Performance and Maintenance - Administrative Tools - Data Sources (ODBC) Under the dialog tab User DSN, press ADD, select the MySQL ODBC X.Y Unicode Driver.

In the dialog, enter the following:

Press the TEST button - it should connect.

Create a database with the Command Line Client
From the Start-All Programs-MySQL menu, start the command line client.


 * Enter the password at the prompt. The prompt should now be: mysql>
 * Enter "show databases;" (without the quotes, but with the semi-colon), and database "fred" should be listed.
 * Enter "use fred"

Now create a table called "person" in "fred":


 * Enter "create table person (name varchar(20), age integer);"
 * Enter "show tables;" (remember the semi-colons)

Enter some data into the table:


 * Enter "insert into person values('fred','87');"

And then check the data is there:


 * Enter "select * from person;"

and the data should be listed.

Close the MySQL session:


 * Enter "quit".

Using MySQL in a Visual Prolog project
Create a new VIP GUI project, and cut and paste the following code into taskwindow.pro, and (e.g.) call predicate test: from File-New.

This example adds one more record to the table "person" and then lists the table. It will also list the data entered previously at the mysql command line prompt (step 5 above).

predicates test:. clauses test:- Connection = odbcConnection::new(256), ConStr = @"DSN=myodbc;UID=root;PW=scott;", if X = Connection:driverConnect(This:getVpiWindow, ConStr, odbc_native::sql_driver_noprompt) then %       OR USE %       Connection:connect("myodbc","root","scott"), stdio::write("Connection info =",X), Stmt = odbcStatement::new(Connection), try Stmt:execDirect("INSERT INTO person VALUES ('harrypotter',4)"), look(Stmt) finally Stmt:free end try, Connection:disconnect end if.

predicates look : (odbcStatement Stmt). clauses look(Stmt) :- Stmt:resetParameter_all, Stmt:execDirect("select * from person"), NumColumns = Stmt:numResultCols, foreach Stmt:fetch_nd do           stdio::nl, foreach Column = convert(odbc_native::fieldIndex, std::fromTo(1, NumColumns)) do               ColName = Stmt:colAttribute_string(Column+0, odbc_native::sql_desc_name), ColValue = Stmt:getColumnValue(Column+0), stdio::writef("% = %, ", ColName, ColValue) end foreach end foreach, Stmt:closeCursor.

Notice that it is very important to "free" odbcStatements; failing to do this will sooner or later result in program breakdown. Therefore the "free" is placed inside a try-finally construction, so that it is also freed in case of exceptions.