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2.3.2 The Column Class

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2.3.2.1 Column::ArrayType
2.3.2.2 Column::StorageType
2.3.2.3 Column::Type
2.3.2.4 Column Methods

Abstract

This class represents a column in an NDB Cluster table.

Parent class. NdbDictionary

Child classes. None

Description. Each instance of Column is characterized by its type, which is determined by a number of type specifiers:

Built-in type
Array length or maximum length
Precision and scale (currently not in use)
Character set (applicable only to columns using string data types)
Inline and part sizes (applicable only to BLOB columns)

These types in general correspond to MySQL data types and their variants. The data formats are same as in MySQL. The NDB API provides no support for constructing such formats; however, they are checked by the NDB kernel.

Methods. The following table lists the public methods of this class and the purpose or use of each method:

Table 2.2 Column class methods and descriptions

Method	Description
`Column()`	Class constructor; there is also a copy constructor
`~Column()`	Class destructor
`equal()`	Compares `Column` objects
`getArrayType()`	Gets the column's array type
`getCharset()`	Get the character set used by a string (text) column (not applicable to columns not storing character data)
`getColumnNo()`	Gets the column number
`getDefaultValue()`	Returns the column's default value
`getInlineSize()`	Gets the inline size of a `BLOB` column (not applicable to other column types)
`getLength()`	Gets the column's length
`getName()`	Gets the name of the column
`getNullable()`	Checks whether the column can be set to `NULL`
`getPartitionKey()`	Checks whether the column is part of the table's partitioning key
`getPartSize()`	Gets the part size of a `BLOB` column (not applicable to other column types)
`getPrecision()`	Gets the column's precision (used for decimal types only)
`getPrimaryKey()`	Check whether the column is part of the table's primary key
`getScale()`	Gets the column's scale (used for decimal types only)
`getSize()`	Gets the size of an element
`getSizeInBytesForRecord()`	Gets the space required for a column by `NdbRecord`, according to the column's type (added in NDB 7.3.10 and NDB 7.4.7)
`getStripeSize()`	Gets a BLOB column's stripe size (not applicable to other column types)
`getStorageType()`	Gets the storage type used by this column
`getType()`	Gets the column's type (`Type` value)
`setArrayType()`	Sets the column's `ArrayType`
`setCharset()`	Sets the character set used by a column containing character data (not applicable to nontextual columns)
`setDefaultValue()`	Sets the column's default value
`setInlineSize()`	Sets the inline size for a `BLOB` column (not applicable to non-`BLOB` columns)
`setLength()`	Sets the column's length
`setName()`	Sets the column's name
`setNullable()`	Toggles the column's nullability
`setPartitionKey()`	Determines whether the column is part of the table's partitioning key
`setPartSize()`	Sets the part size for a `BLOB` column (not applicable to non-`BLOB` columns)
`setPrecision()`	Sets the column's precision (used for decimal types only)
`setPrimaryKey()`	Determines whether the column is part of the primary key
`setScale()`	Sets the column's scale (used for decimal types only)
`setStorageType()`	Sets the storage type to be used by this column
`setStripeSize()`	Sets the stripe size for a `BLOB` column (not applicable to non-`BLOB` columns)
`setType()`	Sets the column's `Type`

For detailed descriptions, signatures, and examples of use for each of these methods, see Section 2.3.2.4, “Column Methods”.

Important

Columns created using this class cannot be seen by the MySQL Server. This means that they cannot be accessed by MySQL clients, and that they cannot be replicated. For these reasons, it is often preferable to avoid working with them.

Important

In the NDB API, column names are handled in case-sensitive fashion. (This differs from the MySQL C API.) To reduce the possibility for error, it is recommended that you name all columns consistently using uppercase or lowercase.

Types. These are the public types of the Column class:

Table 2.3 Column class types and descriptionse.

Type	Description
`ArrayType`	Specifies the column's internal storage format
`StorageType`	Determines whether the column is stored in memory or on disk
`Type`	The column's data type. `NDB` columns have the same data types as found in MySQL

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