Table of Contents
Dictionary Column Attributes
When creating a column in a table using the dictionary methods, the information provided must confirm to the following specification. Each column created has a number of mandatory and optional parameters.
The basic syntax of the attributes is as follows:
- All the information for the column must occur on a single line.
- The line ending may be a newline or carriage return/newline combination.
- Each attribute must be separated by at least one tab or space.
- The attributes must be specified in the order below
- Column Name
- Meta Attributes
- Optional Arguments
/* * Correct syntax */ $flds = " COL1 C(60) NOTNULL DEFAULT 'abc', COL2 I8 NOTNULL DEFAULT 0 "; /* * Incorrect syntax */ $flds = " COL1 C(60) NOTNULL DEFAULT 'abc', COL2 I8 NOTNULL DEFAULT 0 ";
- The column name must conform to any database specific standards related to naming and length. If the name contains spaces, then it should be surrounded by backticks
`col with spaces`. Note that this is an internal designator, and does not represent the character used by the database in SQL statements.
- The column attributes in terms of type and length must be specified in terms of ADODb metaType descriptions, not the database definition for the type.
The following optional arguments may also be assigned to the column, table or key. If the attribute is inappropriate for the operation or column type or not supported by the DBMS, it is ignored.
AUTO or AUTOINCREMENT
Creates the column as auto-increment. Support for this varies from one database to another. Some databases designate a field with an auto-increment flag as the primary key, and most databases only allow a single column in a table to be designated as auto-increment.
Adds a constraint to column. The syntax for the constraint must be defined as required by the database.
DEF or DEFAULT
DEF indicates a default value for a column when a row is created. Some databases also require a field with a default value to be designated as NOT NULL, so that is automatically added to the column string. For dynamically created dates or timestsamps, see the options below.
Indicates if the column (metaType D or T) should be defaulted to current date when a column is created. This differs from the DEFTIMESTAMP option below in that it only contains the date portion of a timestamp.
Indicates if the column (metaType D or T) should be defaulted to current timestamp when a column is created.
In databases that support the ENUM datatype, append a parenthesized, quoted list of enum values
Note that you should not place a space between ENUM and the left parenthises
Creates a single column index using the same name as the column, with 'idx_' prepended to the name, e.g. a column of name
column1 will create an index of name
Prevents ADOdb from applying the normal quoting rules to tables, columns and indexes. For example, a column name that contains a special character such as some-column will be automatically quoted to 'some-column'. This tag prevents the behavior.
Flags the column so that a NULL value cannot be inserted. For columns that are Auto-Increment or a Primary Key, this option is often implied.
PRIMARY or KEY
Indicates if the column is part of the Primary Key of the table.
UNIQUE is an option against a key and indicates that duplicate values across all columns in the key are not allowed.
Creates an unsigned integer.