(Quick Reference)
                column
Purpose
Customizes a column definition
Examples
static mapping = {
        currency column: "currency", sqlType: "char", length: 3
    }Description
Usage: 
property_name(map)Arguments:
- column- The name of the column as a String
- sqlType(optional) - The underlying SQL type
- enumType(optional) - The enum type in for type-safe Enum properties. Either- ordinalor- string.
- index(optional) - The index name
- unique(optional) - Whether it is unique
- length(optional) - The length of the column
- precision(optional) - The precision of the column
- scale(optional) - The scale of the column
By default GORM uses the property name and type to determine how to map a property in the database. For example a 
String property is typically mapped as a 
varchar(255) column. You can customize these with column configuration arguments:
static mapping = {
    currency column: "currency", sqlType: "char", length: 3
}If you use a Hibernate 
type that requires multiple column definitions you can use the 
column method to define each column:
static mapping = {
    amount type: MonetaryUserType, {
        column name: "value"
        column name: "currency", sqlType: "char", length: 3
    }
}