[DBI-users] bind_param_inout

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This is a topic which often causes problems. Mainly due to Oracle's many and sometimes complex ways of specifying and connecting to databases. James Taylor and Lane Sharman have contributed much of the text in this section.

Oracle will construct a full connection descriptor string for you and Oracle will not need to consult bind_param_inout dbi tnsnames. If a port number is not specified then the descriptor will try both and in that order e.

Oracle typically uses two environment variables to specify default connections: In general, the value used should match the version of Bind_param_inout dbi that was used to build DBD:: Oracle was compiled with. You can try using one of the DB variants as a workaround. On bind_param_inout dbi other hand, that may cause bind_param_inout dbi to trip up on another Oracle bug that causes alternating connection attempts to fail!

In reality only a small proportion of people experience these problems. That only works for local databases. Authentication bind_param_inout dbi remote Oracle databases using your unix login name without a password and is possible but it's not secure and not recommended so not documented here.

If you can't find the information elsewhere then you probably shouldn't be trying to do it. My connections over tnslistener on the same humble Netra 1 take an average of milli seconds according to tnsping.

If anyone knows how to make it better, please let me know! You do not need it. I am convinced that this is one of the connection bind_param_inout dbi sockets over the same machine. The essential code bind_param_inout dbi do this at the end of this section. Currently I am not bind_param_inout dbi it in the bind_param_inout dbi. If you are still having problems connecting then the Oracle adapters utility may offer some help.

Run these two commands:. If it generates any errors which look bind_param_inout dbi then please talk to your Oracle bind_param_inout dbi support and not the dbi-users mailing list.

Thanks to Mark Dedlow for this information. But note that version numbers are not actually floating point and so if Oracle ever makes a release that has a two digit minor version, such as 9. So use with care. I recommend bind_param_inout dbi you avoid checking for bind_param_inout dbi values.

Also the username and password should be empty, and the user executing the script needs to be part of the dba group or osdba group. This attribute requires DBD:: Oracle to be built with the -ProC option to Makefile. If the value is 0 then a new OCI environment is allocated and used for this connection. This is most useful for testing. This attribute can be used to limit or extend the number of rows processed at a time.

See Handling LOBs for more details. See also the LOB tests in 05dbi. See Prepare postponed till execute for more information. Please remember that using spaces as a value or at the end of a value makes visually distinguishing values with different numbers of spaces difficult and should be avoided.

Oracle Clients after OCI 9. As the default placeholder type value bind_param_inout dbi DBD:: In Oracle, the concept of user and schema is currently the same.

Because database objects are owned by an user, the owner names in the data dictionary views correspond to schema names. The following table types are supported:. The special enumerations of catalogs, schemas bind_param_inout dbi table types are supported.

An identifier is passed as isi. So, a selection criterion should respect upper and lower case. Normally, an identifier is case-insensitive. Oracle stores and returns it in upper case. Sometimes, database objects are created with quoted identifiers for reserved words, mixed case, special characters, Such an identifier is case-sensitive if not all upper case.

Oracle stores and returns it as given. This is a known Bug in Oracle's data dictionary views. Currently as of 8. Oracle now supports Unicode UTF There are, however, a number of issues you should be aware of, so please read all this section carefully. Information about Unicode in general can be found at: It is well worth reading because there are many misconceptions about Unicode and you may be holding some bind_param_inout dbi them.

Perl began implementing Unicode with version 5. If you plan to use Bind_param_inout dbi you are strongly urged to use perl 5. Oracle supports many characters sets, including several different forms of Unicode. The character sets used in your database can be found using:.

You are strongly urged to read the Bind_param_inout dbi Internationalization documentation specifically with respect the choices and trade offs for creating a databases for use with international character sets. For this reason a number of DBD:: Bind_param_inout dbi tests are disabled when using an Oracle 8 client. If you wish to use Unicode, I recommend upgrading client and server to Bind_param_inout dbi 9 or later.

Here are a couple of extracts from http: Oracle uses this internally because it collates sorts in the same order as UTF16, which is the basis of Oracle's internal collation definitions.

If you're using an Oracle version below 9. Oracle Unicode support has been implemented for Oracle versions 9 or greater, and perl version 5. You can check which Oracle version your DBD:: Any data returned from Oracle to DBD:: When fetching other character data from Oracle, DBD:: These are listed here with the highest precedence first:.

That's useful but inconsistent with the other behaviour so may change. The only multi-byte Oracle character set supported by DBD:: Single-byte character sets should work well. Oracle has built-in support for SYS. The simple example is here:.

If you really need, send request to dbi-dev list. Oracle does not explicitly support most Oracle data types. It simply asks Oracle to return them as bind_param_inout dbi and Oracle does so. Similarly when binding placeholder values DBD:: Oracle binds them as strings and Oracle converts bind_param_inout dbi to the appropriate type, such as DATE, when bind_param_inout dbi. Some of these automatic conversions to and from strings use NLS settings to control the formating for output and the parsing for input.

The most common example is the DATE type. An error will be generated if the contents of the string don't match the NLS format. Perl will bind_param_inout dbi warnings and use incorrect values when numbers, returned and formatted as strings in this way by Oracle, are used in a numeric context. The best fix is to change the NLS settings.

That can be done for an bind_param_inout dbi connection by doing:. These functions are bind_param_inout dbi through the method func which is described in the DBI documentation. The function returns undef if the error string could not be retrieved due to a database bind_param_inout dbi.

If bind_param_inout dbi lines were saved successfully the function returns 1. Depending on the context, an empty list or undef is returned for failure. Some of the text might be in the buffer. In an array context, all complete lines are bind_param_inout dbi from the buffer and returned as a list. If there are no complete lines, an empty list is returned. In a bind_param_inout dbi context, the first complete line is removed from the buffer and returned.

If there are no complete lines, undef is returned. Oracle pre-allocates the whole buffer LongReadLen at bind_param_inout dbi time the statement is prepared.

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The archives are listed at the end of this document and on the DBI home page http: To help you make the best use of the dbi-users mailing list, and any other lists or forums you may use, I recommend that you read "Getting Answers" by Mike Ash: This is the best way to get help.

You don't have to subscribe to the list in order to post, though I'd recommend it. You can get help on subscribing and using the list by emailing dbi-users-help perl. Please note that Tim Bunce does not maintain the mailing lists or the web pages generous volunteers do that. So please don't send mail directly to him; he just doesn't have the time to answer questions personally. The dbi-users mailing list has lots of experienced people who should be able to help you if you need it.

If you do email Tim he is very likely to just forward it to the mailing list. StackOverflow has a DBI tag http: The DBI home page at http: They include links to other resources, but are rather out-dated. If you think you've found a memory leak then read "Memory Leaks".

Your problem is most likely related to the specific DBD driver module you're using. If that's the case then click on the 'Bugs' link on the http: Only submit a bug report against the DBI itself if you're sure that your issue isn't related to the driver you're using. The significant user-visible changes in each release are documented in the DBI:: Changes module so you can read them by executing perldoc DBI:: Some DBI changes require changes in the drivers, but the drivers can take some time to catch up.

Newer versions of the DBI have added features that may not yet be supported by the drivers you use. Talk to the authors of your drivers if you need a new feature that is not yet supported. Features added after DBI 1. See "Naming Conventions and Name Space". DBI extension modules can be found at https: And all modules related to the DBI can be found at https: The DBI is a database access module for the Perl programming language.

It defines a set of methods, variables, and conventions that provide a consistent database interface, independent of the actual database being used. It is important to remember that the DBI is just an interface. The DBI is a layer of "glue" between an application and one or more database driver modules.

It is the driver modules which do most of the real work. The DBI provides a standard interface and framework for the drivers to operate within. This document often uses terms like references , objects , methods.

If you're not familiar with those terms then it would be a good idea to read at least the following perl manuals first: The DBI "dispatches" the method calls to the appropriate driver for actual execution. The DBI is also responsible for the dynamic loading of drivers, error checking and handling, providing default implementations for methods, and many other non-database specific duties. Each driver contains implementations of the DBI methods using the private interface functions of the corresponding database engine.

Note that Perl will automatically destroy database and statement handle objects if all references to them are deleted. Then you need to "connect" to your data source and get a handle for that connection:.

Since connecting can be expensive, you generally just connect at the start of your program and disconnect at the end. Explicitly defining the required AutoCommit behaviour is strongly recommended and may become mandatory in a later version. This determines whether changes are automatically committed to the database when executed, or need to be explicitly committed later.

The DBI allows an application to "prepare" statements for later execution. A prepared statement is identified by a statement handle held in a Perl variable.

To commit your changes to the database when "AutoCommit" is off:. Finally, when you have finished working with the data source, you should "disconnect" from it:.

The DBI does not have a concept of a "current session". Every session has a handle object i. That handle object is used to invoke database related methods.

Most data is returned to the Perl script as strings. Null values are returned as undef. This allows arbitrary precision numeric data to be handled without loss of accuracy. Beware that Perl may not preserve the same accuracy when the string is used as a number.

Dates and times are returned as character strings in the current default format of the corresponding database engine. Perl supports binary data in Perl strings, and the DBI will pass binary data to and from the driver without change. It is up to the driver implementors to decide how they wish to handle such binary data. Perl supports two kinds of strings: Unicode utf8 internally and non-Unicode defaults to iso if forced to assume an encoding.

Drivers should accept both kinds of strings and, if required, convert them to the character set of the database being used. Similarly, when fetching from the database character data that isn't iso the driver should convert it into utf8.

Non-sequential record reads are not supported in this version of the DBI. In other words, records can only be fetched in the order that the database returned them, and once fetched they are forgotten.

Positioned updates and deletes are not directly supported by the DBI. See the description of the CursorName attribute for an alternative. Private driver functions can be invoked using the DBI func method. Private driver attributes are accessed just like standard attributes. Extensions and related modules use the DBIx:: Package names beginning with DBD:: The letter case used for attribute names is significant and plays an important part in the portability of DBI scripts.

The case of the attribute name is used to signify who defined the meaning of that name and its values. It is of the utmost importance that Driver developers only use lowercase attribute names when defining private attributes. Private attribute names must be prefixed with the driver name or suitable abbreviation e. The DBI itself does not mandate or require any particular language to be used; it is language independent.

The only requirement is that queries and other statements must be expressed as a single string of characters passed as the first argument to the "prepare" or "do" methods. Some drivers support placeholders and bind values. Placeholders , also called parameter markers, are used to indicate values in a database statement that will be supplied later, before the prepared statement is executed.

The association of actual values with placeholders is known as binding , and the values are referred to as bind values. Some drivers also allow placeholders like: Check your driver documentation.

The driver will remove the backslash character and ignore the placeholder, passing it unchanged to the backend. With most drivers, placeholders can't be used for any element of a statement that would prevent the database server from validating the statement and creating a query execution plan for it.

Also, placeholders can only represent single scalar values. For example, the following statement won't work as expected for more than one value:. So you should use " Undefined values, or undef , are used to indicate NULL values. These examples insert and update the column age with a NULL value:.

At least for database engines that conform to the SQL standard. A simple technique is to prepare the appropriate statement as needed, and substitute the placeholder for non-NULL cases:.

The techniques above call prepare for the SQL statement with each call to execute. Because calls to prepare can be expensive, performance can suffer when an application iterates many times over statements like the above. Its SQL statement would need to be prepared only once for all cases, thus improving performance.

But each example lacks portability, robustness, or simplicity. Whether an example is supported on your database engine depends on what SQL extensions it provides, and where it supports the? The arguments are required, whether their values are defined or undef.

Example 0 should not work as mentioned earlier , but may work on a few database engines anyway e. Example 0 is part of examples 4, 5, and 6, so if example 0 works, these other examples may work, even if the engine does not properly support the right hand side of the OR expression. Examples 1 and 2 are not robust: That means you must have some notion of what data won't be stored in the column, and expect clients to adhere to that.

Example 6, the least simple, is probably the most portable, i. Here is a table that indicates which examples above are known to work on various database engines:.