hk_column
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## hk_column

Represents one column of a datasource. The data of the current row (set in hk_datasource) can be modified by using the functions set_asstring(), set_asbool(),set_asdouble, set_asinteger and set_asbinary(). and read by using the functions asstring(), asbool(), asdouble(), asinteger() and asbinary().

If the the datasource is in alter or create mode you can change the column definition by using the following functions: set_name(), set_columntype(), set_size(), set_notnull(), set_primary()

Inherits from hk_class.

Figure 2.3. hk_column data methods

> set_asstring(value)

>   lets you set a new value for this object

> asstring()

>   returns the current value as a string value

> set_asdouble(value)

>   lets you set a new value for this object

> asdouble()

>   returns the current value as a double value

> set_asinteger(value)

>   lets you set a new value for this object

> asinteger()

>   returns the current value as a integer value

> is_readonly()

>   returns true if this column is read-only; if data can be changed it returns false

> find(from_rownumber,to_rownumber,searchtext[,wholephrase[,casesensitive[,backwards]]])

>   searches for a specific value in a column, returns the row number if found, hk_datasource.max_rows()+1 if not found

> find(searchtext[,wholephrase[,casesensitive[,backwards]]])

>   searches for a specific value in a column, returns the row number if found, hk_datasource.max_rows()+1 if not found. This version searches all rows of a datasource.

> datasource()

>   returns the hk_datasource object, to which this hk_column belongs to.

> count()

>   returns the number of rows that contain 'Not NULL' values

> count(from,to)

>   returns the number of rows that contain 'Not NULL' values, starting at position 'from' and counting to position 'to'

> sum()

>   returns the sum of all rows

> sum(from,to)

>   returns the sum of all rows, starting at position 'from' and counting to position 'to'

Example 2.3. Read data

    col=hk_this.datasource().column_by_name("name")
    hk_this.show_warningmessage(col.asstring())

Example 2.4. Write data

    col=hk_this.datasource().column_by_name("name")
    col.set_asstring("my new value")

This changes the value of the current column. The data is saved either when

- the row position changes (e.g. by calling hk_datasource.goto_row())

- the datasource is disabled (e.g. by calling hk_datasource.disable())

- the changes are manually stored by calling hk_datasource.store_changed_data()

Example 2.5. Search data

    col=hk_this.datasource().column_by_name("name")
    result=col.find("Schiller")
    if result > hk_this.datasource().max_rows():
         hk_this.show_warningmessage("value not found")
    else:
         hk_this.show_warningmessage("Value found at row position: "+str(result))

Figure 2.4. hk_column type methods

> name()

>   returns the name of this column

> set_name(name)

>   sets the column name

> set_columntype(type)

>   sets the type of the column

>   Possible values are

>   - textcolumn

>   - auto_inccolumn

>   - smallintegercolumn

>   - integercolumn

>   - smallfloatingcolumn

>   - floatingcolumn

>   - datecolumn

>   - datetimecolumn

>   - timecolumn

>   - timestampcolumn

>   - binarycolumn

>   - memocolumn

>   - boolcolumn

>   - othercolumn

> columntype()

>   returns the type of the column.

> set_size()

>   sets the column size (e.g. if this column was should be a textcolumn with 10 characters set the type with set_type and the size with this function)

> size()

>   returns the column size (e.g. if this column was created as CHAR(10) it will return 10)

> set_primary(primary)

>   if 'primary' is true the column will be part of the primary key (primary index). Can only be edited if the datasource is in the mode ALTER or CREATE.

> is_primary()

>   returns true if this column is part of a primary key

> set_notnull(notnull)

>   if 'notnull' true the column needs a value

> is_notnull()

>   returns True if this column has to have a value

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