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Daanse Tutorial - Database Column ​

The data of a table are seperated into columns. Each column that should be used, must be explicitly defined. Columns that are not relevant for the analysis can be left out.

Common column fields ​

A Column has the fields id, name, description and nullable. Id is used to reference the column. Name is the name of the Column in the Database-table. Description is a human-readable textual description of the column. Nullable is an boolean flag, that indicates if the column can contain null values.

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columnwithdescription" name="ColumnWithDescription"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Types of Columns ​

In database tables, columns can have various data types to store data efficiently. These types come with additional attributes that provide more detailed descriptions and constraints.

Varchar ​

The ColumnSize field in represents the maximum width or precision of a column, depending on its data type. It provides essential information about how much data a column can store

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columnvarchar" name="ColumnVarchar"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Decimal ​

DECIMAL type represents Fixed-point number with exact precision (p) and scale (s), used for precise calculations (e.g., financial data).

relevant attributes are:

The DecimalDigits field represents the number of digits to the right of the decimal point for numeric columns in a database. It is typically used for DECIMAL, NUMERIC, FLOAT, REAL, and DOUBLE data types.

The NumPrecRadix field represents the numeric precision radix (or base) used for numeric data types. It indicates whether the precision (COLUMN_SIZE) of a column is based on base 10 (decimal) or base 2 (binary).

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columndecimal" name="ColumnDecimal"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Numeric ​

Numeric are the same as DECIMAL, but some databases treat it as stricter in enforcing precision.

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columnnumeric" name="ColumnNumeric"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Float ​

Float Approximate floating-point number, implementation-dependent precision, can introduce rounding errors

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columnfloat" name="ColumnFloat"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Real ​

REAL are Single-precision (32-bit) floating-point number, less precise than DOUBLE.

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columnreal" name="ColumnReal"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Double ​

DOUBLE (or DOUBLE PRECISION) – Double-precision (64-bit) floating-point number, more accurate than REAL.

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columndouble" name="ColumnDouble"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Integer ​

INTEGER are the whole number type, typically 32-bit, used for exact, non-decimal values.

xml
<relational:Column xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_column_columninteger" name="ColumnInteger"/>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Definition ​

This file represents the complete definition of the catalog.

xml
<?xml version="1.0" encoding="UTF-8"?>
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolapcat="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/catalog">
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_character_varying" name="CHARACTER VARYING" structuralFeature="_column_tablewithcolumntypes_columnvarchar _column_tablewithcolumntypes_columnwithdescription" typeNumber="12"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_decimal" name="DECIMAL" structuralFeature="_column_tablewithcolumntypes_columndecimal" typeNumber="3" numericPrecision="18" numericPrecisionRadix="10" numericScale="4"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_double_precision" name="DOUBLE PRECISION" structuralFeature="_column_tablewithcolumntypes_columndouble" typeNumber="8" numericPrecisionRadix="2"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_float" name="FLOAT" structuralFeature="_column_tablewithcolumntypes_columnfloat" typeNumber="6" numericPrecisionRadix="2"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_integer" name="INTEGER" structuralFeature="_column_tablewithcolumntypes_columninteger" typeNumber="4"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_numeric" name="NUMERIC" structuralFeature="_column_tablewithcolumntypes_columnnumeric" typeNumber="2" numericPrecision="18" numericPrecisionRadix="10" numericScale="4"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_real" name="REAL" structuralFeature="_column_tablewithcolumntypes_columnreal" typeNumber="7" numericPrecisionRadix="2"/>
  <rolapcat:Catalog xmi:id="_catalog_database_column" description="Database column types and configuration" name="Daanse Tutorial - Database Column" dbschemas="_schema"/>
  <relational:Schema xmi:id="_schema">
    <ownedElement xsi:type="relational:Table" xmi:id="_table_tablewithcolumntypes" name="TableWithColumnTypes">
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columnwithdescription" name="ColumnWithDescription" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columnvarchar" name="ColumnVarchar" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columndecimal" name="ColumnDecimal" type="_sqlsimpletype_decimal"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columnnumeric" name="ColumnNumeric" type="_sqlsimpletype_numeric"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columnfloat" name="ColumnFloat" type="_sqlsimpletype_float"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columnreal" name="ColumnReal" type="_sqlsimpletype_real"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columndouble" name="ColumnDouble" type="_sqlsimpletype_double_precision"/>
      <feature xsi:type="relational:Column" xmi:id="_column_tablewithcolumntypes_columninteger" name="ColumnInteger" type="_sqlsimpletype_integer"/>
    </ownedElement>
  </relational:Schema>
</xmi:XMI>

Tutorial Zip ​

This file contains the data-tables as csv and the mapping as xmi file.

Download Zip File

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