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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
BLOBcolumns)
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:
| Method | Purpose / Use |
|---|---|
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:
| Type | Purpose / Use |
|---|---|
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 |
Class diagram.
This diagram shows all the available methods and enumerated types
of the Column class:
