MacLochlainns Weblog

I saw a post in the OTN forum that asked a simple question and had no simple example as an answer, so I thought it would be nice to provide one. Basically, somebody wanted to know how to call into a stored procedure and return a value with more or less one pass-by-value and another pass-by-reference variable.

This defines a simple echo procedure, which takes a message and returns a formatted message:

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CREATE OR REPLACE PROCEDURE echo
( message IN     VARCHAR2
, reply      OUT VARCHAR2 ) IS
BEGIN
  reply := 'Message ['||message||'] received.';
END;
/

The following PHP calls the procedure and returns the value. It uses the required connection syntax for the Zend Server Community Edition.

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<?php
  // Attempt to connect to your database.
  $c = @oci_connect("student", "student", "localhost/xe");
  if (!$c) {
    print "Sorry! The connection to the database failed. Please try again later.";
    die();
  }
  else {
    // Initialize incoming message whether or not parameter sent.
    $msg_in = (isset($_GET['msg'])) ? $_GET['msg'] : "Cat got your keyboard?";
 
    // Set the call statement, like a SQL statement.
    $sql = "BEGIN echo(:a,:b); END;";
 
    // Prepare the statement and bind the two strings.
    $stmt = oci_parse($c,$sql);
 
    // Bind local variables into PHP statement, you need to size OUT only variables.
    oci_bind_by_name($stmt, ":a", $msg_in);
    oci_bind_by_name($stmt, ":b", $msg_out, 80, SQLT_CHR);
 
    // Execute it and print success or failure message.
    if (oci_execute($stmt)) {
      print $msg_out;
    }
    else {
      print "Sorry, I can't do that Dave...";
    }
    // Free resources.
    oci_free_statement($stmt);
    oci_close($c);
  }
?>

You can then test it with or without a parameter, like this example with a parameter:

http://localhost/message_reply.php?msg="Sample message"

I put a link in the forum to this, and I hope it helps a few folks.

I got all the screen shots out last night, then I realized that the configuration instructions were missing. They’ve been added now, and you can check if you’re interested.

In the process, I noticed that Zend Server Community Edition is using connection pooling by default with Oracle. This means that the TNS alias must be qualified by a hostname.

For example, on your local PC with Oracle Database 10g Express Edition, the default TNS alias is XE. You can’t use that anymore when you’re running the Zend Server. You must qualify it as localhost/XE or hostname/XE as the connection string. A natural alternative is to insert a fully qualified TNS network map

Here are three possible connection patterns:

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<?php
  // Attempt to connect to your database.
  $c = @oci_connect("student", "student", "localhost/xe");
  if (!$c) {
    print "Sorry! The connection to the database failed. Please try again later.";
    die();
  }
  else {
    print "Congrats! You've connected to an Oracle database!";
    oci_close($c);
  }
?>

02-JUL-2009 23:32:11 * (CONNECT_DATA=(SERVICE_NAME=xe)(CID=(PROGRAM=C:\Program?Files\Zend\ZendServer\bin\php-cgi.exe)(HOST=MCLAUGHLINXP32)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1405)) * establish * xe * 0

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<?php
  // Attempt to connect to your database.
  $c = @oci_connect("student", "student", "localhost/xe");
  if (!$c) {
    print "Sorry! The connection to the database failed. Please try again later.";
    die();
  }
  else {
    print "Congrats! You've connected to an Oracle database!";
    oci_close($c);
  }
?>

02-JUL-2009 23:29:16 * (CONNECT_DATA=(SERVICE_NAME=xe)(CID=(PROGRAM=C:\Program?Files\Zend\ZendServer\bin\php-cgi.exe)(HOST=MCLAUGHLINXP32)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=172.16.153.138)(PORT=1403)) * establish * xe * 0

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<?php
  $tns = "(DESCRIPTION =
              (ADDRESS=(PROTOCOL = TCP)(HOST = mclaughlinxp32)(PORT = 1521))
              (CONNECT_DATA=(SERVER = DEDICATED)(SERVICE_NAME = XE)))";
 
  // Attempt to connect to your database.
  $c = @oci_connect("student", "student", $tns);
  if (!$c) {
    print "Sorry! The connection to the database failed. Please try again later.";
    die();
  }
  else {
    print "Congrats! You've connected to an Oracle database!";
    oci_close($c);
  }
?>

02-JUL-2009 23:27:10 * (CONNECT_DATA=(SERVICE_NAME=XE)(CID=(PROGRAM=C:\Program?Files\Zend\ZendServer\bin\php-cgi.exe)(HOST=MCLAUGHLINXP32)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=172.16.153.138)(PORT=1401)) * establish * XE * 0

I’m sure it was in the documents but then again, I didn’t read them.

The Zend Core Server replaces the deprecated Zend Core for Oracle. I’ve put a quick installation guide here. It’s much nicer, and the licensed server is now the recommended direction from Oracle.

The community edition also installs MySQL, phpMySQLAdmin, and a brand new console. You should try it out.

A colleague of mine just dropped by his new book on Developing Hybrid Applications for the iPhone. He covers Dashcode, Xcode, JavaScript, and Objective-C. He also covers how to use WebView and native SQLite database access from the iPhone.

It looks interesting. By the way, his blog is here.

I finally got around to summarizing how to use PHP to store, retrieve, and display CLOBs and BLOBs from an Oracle database. I think too often we default to BFILEs. I put all the code in zip files with instructions and suggestions for locations. This is really the second entry that goes with configuring Zend Server Community Edition or the DEPRECATED Zend Core for Oracle.

If you’re new to PHP, check out the Underground PHP and Oracle book from Christopher Jones and Alison Holloway. It’s FREE!

The Oracle LOB Processing entry is in this blog page. I know it means another click, but I’ll probably add and modify it over time. If you’ve got time and interest, take a look and let me know what you think and what improvements you’d like to see. Thanks.

I finally got around to creating a blog page that shows you how to install Zend Core for Oracle, verify the installation of PHP, your connection to an Oracle XE database with PHP, and your connection to a MySQL database with PHP.

It’s using the folding concepts I’ve adopted in the blog. One section unfolds to display screen shots for the installation of Zend Core for Oracle. Another section shows you how to confirm your PHP and Apache installation. Two other sections show you how to confirm your connection to an Oracle or MySQL database.

I apologize to those who don’t like to click through to another page, but it was a long page with 20+ images. Hope it helps a few folks, I know it’ll help my students.

My students have to do their group labs in Oracle and then port them individually to MySQL. Most of the conversion resolves around dates because Oracle spoils us with their simplicity in their SQL dialect.

For example, if we wanted to add 9 days to today’s system date (June 27, 2009) we can do this in Oracle:

SQL> SELECT SYSDATE + 9 FROM dual;

It prints

06-JUL-09

If we tried the equivalent in MySQL, we get a null because it treats any day value over 31 as a null. The maximum date in any month is 31, regardless of month. If you add more days than the maximum number minus your current date, you return a null. This is because adding a day never changes the month, and that yields invalid dates. In MySQL, you need to make this calculation with the adddate() or date_add() functions because they’ll increment months and years.

By way of example, if we only added four to today’s date (June 27, 2009) and formatted the output as a date, it works

mysql> SELECT str_to_date(utc_date() + 4,'%Y%m%d');

We’d get this:

+--------------------------------------+
| str_to_date(utc_date() + 4,'%Y%m%d') |
+--------------------------------------+
| 2009-06-31                           |
+--------------------------------------+

I always wanted an extra day in June.

In short, there are three possible non-dates in February that format as dates, and one day in every thirty day month. I’ve a hunch this is a bug (I’ve logged a bug and they’ve verified it and moved it to triage).

The correct way to perform this calculation in MySQL is to use either the adddate() or date_add() functions. They take the same arguments. Here’s a quick example:

mysql> SELECT adddate(utc_date(),INTERVAL 9 DAY);

It yields the correct date:

+------------------------------------+
| adddate(utc_date(),INTERVAL 9 DAY) |
+------------------------------------+
| 2009-07-06                         |
+------------------------------------+

I know this answers a student email but I hope it helps a few others too.

Never change something that works! Not really, but sometimes you feel that way. Especially, when you toast 5 to 10 minutes working through an undocumented behavior in PL/SQL. You’d think after writing it for 19 years, I’d have seen it all but not so.

I was working through a tried and true example from Chapter 14 of the Oracle Database 11g PL/SQL Programming book to prepare for teaching my class tomorrow, when I found this nice quirk. It took a few minutes to figure out what was happening, but here it is so you don’t have to look for it too. You can only use variable names that are attributes of the object type as formal parameters in object type constructors. If you try to vary it, you’ll trigger the following exception:

LINE/COL ERROR
-------- -----------------------------------------------------------------
4/11     PL/SQL: Item ignored
4/26     PLS-00307: too many declarations of 'HELLO_THERE' match this call
6/5      PL/SQL: Statement ignored
6/13     PLS-00320: the declaration of the type of this expression IS incomplete OR malformed

All I did to trigger this exception was change the who variable to make it scope specific, like iv_who for instance variable, pv_who for parameter variable, and lv_who for local variable.

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CREATE OR REPLACE TYPE hello_there IS OBJECT
( iv_who VARCHAR2(20)
, CONSTRUCTOR FUNCTION hello_there
  RETURN SELF AS RESULT
, CONSTRUCTOR FUNCTION hello_there
  ( pv_who VARCHAR2 )
  RETURN SELF AS RESULT
, MEMBER FUNCTION get_who RETURN VARCHAR2
, MEMBER PROCEDURE set_who (pv_who VARCHAR2)
, MEMBER PROCEDURE to_string )
INSTANTIABLE NOT FINAL;
/

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CREATE OR REPLACE TYPE BODY hello_there IS
 
  CONSTRUCTOR FUNCTION hello_there RETURN SELF AS RESULT IS
    hello HELLO_THERE := hello_there('Generic Object.');
  BEGIN
    self := hello;
    RETURN;
  END hello_there;
 
  CONSTRUCTOR FUNCTION hello_there (pv_who VARCHAR2) RETURN SELF AS RESULT IS
 
  BEGIN
    self.iv_who := pv_who;
    RETURN;
  END hello_there;
 
  MEMBER FUNCTION get_who RETURN VARCHAR2 IS
  BEGIN
    RETURN self.iv_who;
  END get_who;
 
  MEMBER PROCEDURE set_who (pv_who VARCHAR2) IS
  BEGIN
    self.iv_who := pv_who;
  END set_who;
 
  MEMBER PROCEDURE to_string IS
  BEGIN
    dbms_output.put_line('Hello '||self.iv_who);
  END to_string;
 
END;
/

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CREATE OR REPLACE TYPE hello_there IS OBJECT
( iv_who VARCHAR2(20)
, CONSTRUCTOR FUNCTION hello_there
  RETURN SELF AS RESULT
, CONSTRUCTOR FUNCTION hello_there
  ( iv_who VARCHAR2 )
  RETURN SELF AS RESULT
, MEMBER FUNCTION get_who RETURN VARCHAR2
, MEMBER PROCEDURE set_who (pv_who VARCHAR2)
, MEMBER PROCEDURE to_string )
INSTANTIABLE NOT FINAL;
/

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CREATE OR REPLACE TYPE BODY hello_there IS
 
  CONSTRUCTOR FUNCTION hello_there RETURN SELF AS RESULT IS
    hello HELLO_THERE := hello_there('Generic Object.');
  BEGIN
    self := hello;
    RETURN;
  END hello_there;
 
  CONSTRUCTOR FUNCTION hello_there (iv_who VARCHAR2) RETURN SELF AS RESULT IS
 
  BEGIN
    self.iv_who := iv_who;
    RETURN;
  END hello_there;
 
  MEMBER FUNCTION get_who RETURN VARCHAR2 IS
  BEGIN
    RETURN self.iv_who;
  END get_who;
 
  MEMBER PROCEDURE set_who (pv_who VARCHAR2) IS
  BEGIN
    self.iv_who := pv_who;
  END set_who;
 
  MEMBER PROCEDURE to_string IS
  BEGIN
    dbms_output.put_line('Hello '||self.iv_who);
  END to_string;
 
END;
/

This is certainly interesting. I’ve no clue why such a limitation exists. The name of a parameter list member in the constructor should be independent from the attribute of a user object.

Somebody asked me why you must provide the IDENTIFIED BY password clause on a grant after you’ve already created the user. This is a very good question, I wondered it myself a while back. This blog provides the what, why, and how of it.

The reason you typically must provide the IDENTIFIED BY password clause is that typically you’ve enabled the NO_AUTO_CREATE_USER value in your sql_mode. That parameter is there by default from MySQL 5.0.2 forward. It’s what requires you to use the IDENTIFIED BY password clause.

The parameter enforces a match against user, host, and password columns in the user table of the mysql database. If you disable it, the match is on user and host columns in the user table. If you make a grant to a user without specifying a host and a wildcard (%) host doesn’t exist for that user, the grant will insert a duplicate user. The same user name with a wildcard host trumps the one with a localhost host value for access privileges, which means that user no longer needs a password to gain entry to the database.

The following steps will show and explain what happens in MySQL’s security model.

1. Sign on as the root user, then create a new myuser user:

mysql> CREATE USER 'myuser'@'localhost' IDENTIFIED BY 'myuser'@'localhost';

If you attempt to grant permissions to the myuser without a password value, like this

mysql> GRANT ALL ON sampledb.* TO 'myuser'@'localhost';

You should see an outcome like the following. At least, you will when the NO_AUTO_CREATE_USER value is set in your sql_mode variable.

ERROR 1133 (42000): Can't find any matching row in the user table

If it let you set it, then the NO_AUTO_CREATE_USER value isn’t set. You can check what’s set with this query:

mysql> SELECT @@sql_mode;

You should see this:

+----------------------------------------------------------------+
| @@sql_mode                                                     |
+----------------------------------------------------------------+
| STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+----------------------------------------------------------------+

2. Reset the sql_mode to disable the NO_AUTO_CREATE_USER value, like this (presuming you’ve got the generic MySQL 5.1 settings):

mysql> SET sql_mode='STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION';

3. After disabling the restriction, you can grant privileges on a sampledb to the myuser user without the IDENTIFIED BY password clause. You’d use the following syntax:

mysql> GRANT ALL ON sampledb.* TO 'myuser'@'localhost';

Before you sign off and sign on to test your new user, you should now query the USER table. Here’s the query to focus on the three important columns:

mysql> SELECT user, host, password
    -> FROM user
    -> WHERE user = 'myuser';

If you return more than one row, you made an error and most likely left off the @'localhost' or used @'%'. If you made that mistake, you’ll find that disabling the NO_AUTO_CREATE_USER value, can yield multiple entries in the user table for the same user. Worse yet, the user no longer can sign in with their password.

+--------+-----------+-------------------------------------------+
| user   | host      | password                                  |
+--------+-----------+-------------------------------------------+
| myuser | %         |                                           |
| myuser | localhost | *CBA73BBE5D9AF59311C3F4D7E8C20AA847F7B188 |
+--------+-----------+-------------------------------------------+

If you were to sign off and attempt to sign on with the myuser account password, you’d get the following error message:

ERROR 1045 (28000): Access denied FOR user 'myuser'@'localhost' (USING password: YES)

You can now sign on as the myuser user only without a password. Fixing it is simple, just drop the user for any host:

mysql> DROP USER 'myuser'@'%';

While disabling the sql_mode parameters makes your job of granting privileges easier, it risks compromising your database. Therefore, avoid it or be careful. If I missed something or got it wrong, let me know.

I put together a post on how to upload to MySQL from a CSV file with dates. It was more or less for my students but one of them was curious how the mega formula worked. As commented, the easier solution is to create a custom format. Oddly, Open Office does support the MySQL default format natively.

Excel doesn’t support the native MySQL date format, which is YYYYMMDD, or 20090602 for June 2, 2009. That means you have to convert it from a scalar date to a string. If you just shook your head at the term scalar date, let me explain that Excel supports only three data types. They’re a string literal, a numeric literal, and a formula. Dates in Excel are merely formatted numbers. When the numbers are integers, the date is a date, but when the number has a fractional component, the date is really a timestamp.

Here’s a brief description of the process required to convert a date in Excel into a MySQL date format string literal in a CSV file. You need the following Excel functions:

Date Functions

• The DAY(date) function returns a 1 or 2 digit numeric value for the day of the month, with ranges of 1 to 28, 1 to 29, 1 to 30, or 1 to 31 dependent on the month and year.
• The MONTH(date) function returns a 1 or 2 digit numeric value for the month of the year.
• The YEAR(date) function returns a 4 digit numeric value for the year.

Logical Functions

• The IF(logical_expression,truth_action,false_action) function returns the truth action when the expression is true, and the false action when the expression isn’t true.

MySQL Server

• CONCATENATE(string_1, string_2, …) glues strings together.
• LEN(numeric_value) function returns the length of a string or number.

MySQL requires that you return an eight character string of numbers. The first four numbers must be a valid year, the fifth and sixth numbers a valid month, and the seventh and eigth numbers a valid day in the context of the year and month provided. Unfortunately, the DAY() and MONTH() functions may return a 1 or 2 digit value. That can’t happen in the CSV file’s string for a date, so you use the IF() and LEN() functions to guarantee a 2 digit return value.

Here are the examples that guarantee 2 digit day and month values, assuming that the base date is in the A1 cell. The concatenation of a "0" (zero between two double quotes) or the "" (two double quotes or a string null) ensures the number data types become strings.

=IF(LEN(DAY(A1)) = 1,CONCATENATE("0",DAY(A1)),CONCATENATE("",DAY(A1)))
=IF(LEN(MONTH(A1)) = 1,CONCATENATE("0",MONTH(A1)),MONTH(A1))

A zero is placed before the day or month when the logical condition is met, which means the day or month value is a single digit string. A null is place before the day or month when the logical condition isn’t met, which means the day or month value is a two digit string.
There’s only one problem with these mega functions. They return a number.

The year calculation doesn’t require the explicit casting when you concatenate it with the other strings because it is implicity cast as a string. However, it’s a better practice to include it for clarity (most folks don’t know about the implicit casting behaviors in Excel).

=CONCATENATE(CONCATENATE("",YEAR(A1)),IF(LEN(MONTH(A1)),CONCATENATE("0",MONTH(A1))),IF(LEN(DAY(A1)) = 1,CONCATENATE("0",DAY(A1)),CONCATENATE("",DAY(A1))))

You can see the full MySQL import from CSV in the previous post. Naturally, you may want to copy and paste special the value before creating the CSV file. Also, don’t forget to delete any unused columns to the right or rows beneath because if you don’t your file won’t map to your table definition.