--- name: "Alzabo::Create::Column" section: "3pm" platform: "linux" package: "libalzabo-perl" version: "0.92-6" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/Alzabo::Create::Column" --- # Alzabo::Create::Column(3pm) Column objects for use in schema creation ## NAME Alzabo::Create::Column - Column objects for use in schema creation ## SYNOPSIS ``` use Alzabo::Create::Column; ``` ## DESCRIPTION This object represents a column. It holds data specific to a column. Additional data is held in a `"Alzabo::Create::ColumnDefinition"` object, which is used to allow two columns to share a type (which is good when two columns in different tables are related as it means that if the type of one is changed, the other is also.) ## INHERITS FROM `"Alzabo::Column"` Note: all relevant documentation from the superclass has been merged into this document. ## METHODS ### new The constructor accepts the following parameters: - • table =\> `"Alzabo::Create::Table"` object - • name =\> `$name` - • nullable =\> 0 or 1 (optional) Defaults to false. - • sequenced =\> 0 or 1 (optional) Defaults to false. - • default =\> `$default` (optional) - • default\_is\_raw =\> `$boolean` (optional) If "default\_is\_raw" is true, then it will not be quoted when passed to the DBMS in SQL statements. This should be used to allow a default which is a function, like `"NOW()"`. - • attributes =\> \\@attributes (optional) - • length =\> `$length` (optional) - • precision =\> `$precision` (optional) One of either ... - • type =\> `$type` ... or ... - • definition =\> `"Alzabo::Create::ColumnDefinition"` object - • comment =\> `$comment` An optional comment. It returns a new `"Alzabo::Create::Column"` object. Throws: `"Alzabo::Exception::Params"` ### type Returns the column's type as a string. ### alter This method allows you to change a column's type, length, and precision as a single operation. It should be instead of calling `"set_type()"` followed by `"set_length()"`. It takes the following parameters: - • type =\> `$type` - • length =\> `$length` (optional) - • precision =\> `$precision` (optional) Throws: `"Alzabo::Exception::Params"`, `"Alzabo::Exception::RDBMSRules"` ### set\_type ($type) Sets the column's type. Throws: `"Alzabo::Exception::Params"`, `"Alzabo::Exception::RDBMSRules"` ### set\_table ("Alzabo::Create::Table" object) Sets the `"Alzabo::Create::Table"` object in which this column is located. Throws: `"Alzabo::Exception::Params"` ### name Returns the column's name as a string. ### set\_name ($name) Sets the column's name (a string). Throws: `"Alzabo::Exception::Params"`, `"Alzabo::Exception::RDBMSRules"` ### nullable Returns a boolean value indicating whether or not NULLs are allowed in this column. ### set\_nullable (0 or 1) Sets the nullability of the column (this determines whether nulls are allowed in the column or not). Must be 0 or 1. Throws: `"Alzabo::Exception::Params"` ### attributes A column's attributes are strings describing the column (for example, valid attributes in MySQL are 'UNSIGNED' or 'ZEROFILL'. This method returns a list of strings of such strings. ### has\_attribute This method can be used to test whether or not a column has a particular attribute. By default, the check is case-insensitive. It takes the following parameters: - • attribute =\> `$attribute` - • case\_sensitive =\> 0 or 1 (defaults to 0) It returns a boolean value indicating whether or not the column has this particular attribute. ### set\_attributes (@attributes) Sets the column's attributes. These are strings describing the column (for example, valid attributes in MySQL are "PRIMARY KEY" or "AUTO\_INCREMENT"). Throws: `"Alzabo::Exception::RDBMSRules"` ### add\_attribute ($attribute) Add an attribute to the column's list of attributes. Throws: `"Alzabo::Exception::RDBMSRules"` ### delete\_attribute ($attribute) Delete the given attribute from the column's list of attributes. Throws: Throws: `"Alzabo::Exception::Params"`, `"Alzabo::Exception::RDBMSRules"` ### default Returns the default value of the column as a string, or undef if there is no default. ### set\_default ($default) Sets the column's default value. ### length Returns the length attribute of the column, or undef if there is none. ### precision Returns the precision attribute of the column, or undef if there is none. ### set\_length This method takes the following parameters: - • length =\> `$length` - • precision =\> `$precision` (optional) This method sets the column's length and precision. The precision parameter is optional (though some column types may require it if the length is set). Throws: `"Alzabo::Exception::RDBMSRules"` ### sequenced The meaning of a sequenced column varies from one RDBMS to another. In those with sequences, it means that a sequence is created and that values for this column will be drawn from it for inserts into this table. In databases without sequences, the nearest analog for a sequence is used (in MySQL the column is given the AUTO\_INCREMENT attribute, in Sybase the identity attribute). In general, this only has meaning for the primary key column of a table with a single column primary key. Setting the column as sequenced means its value never has to be provided to when calling `"Alzabo::Runtime::Table->insert"`. Returns a boolean value indicating whether or not this column is sequenced. ### set\_sequenced (0 or 1) Sets the value of the column's sequenced attribute. Throws: `"Alzabo::Exception::Params"`, `"Alzabo::Exception::RDBMSRules"` ### is\_primary\_key Returns a boolean value indicating whether or not this column is part of its table's primary key. ### is\_numeric Returns a boolean value indicating whether the column is a numeric type column. ### is\_character Returns a boolean value indicating whether the column is a character type column. This is true only for any columns which are defined to hold *text* data, regardless of size. ### is\_blob Returns a boolean value indicating whether the column is a blob column. This is true for any columns defined to hold binary data, regardless of size. ### definition The definition object is very rarely of interest. Use the `"type()"` method if you are only interested in the column's type. This methods returns the `"Alzabo::Create::ColumnDefinition"` object which holds this column's type information. ### set\_definition ("Alzabo::Create::ColumnDefinition" object) Sets the `"Alzabo::Create::ColumnDefinition"` object which holds this column's type information. ### former\_name If the column's name has been changed since the last time the schema was instantiated, this method returns the column's previous name. ### comment Returns the comment associated with the column object, if any. ### set\_comment ($comment) Set the comment for the column object.