Beginning SQL Server Modeling- P7

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Beginning SQL Server Modeling- P7 CHAPTER 5  M – THE MODELING LANGUAGEDecimal28 A fixed point or exact number.Decimal38 A fixed point or exact number.Integer A signed integer.Integer8 A signed integer with fewer than 9 bits of precision.Integer16 A signed integer with fewer than 17 bits of precision.Integer32 A signed integer with fewer than 33 bits of precision.Integer64 A signed integer with fewer than 65 bits of precision.Scientific A floating-point or exact number.Single A 32-bit floating-point or exact number.Double A 64-bit floating-point or exact number.Unsigned An unsigned integer.Unsigned8 An unsigned integer with fewer than 9 bits of precision.Unsigned16 An unsigned integer with fewer than 17 bits of precision.Unsigned32 An unsigned integer with fewer than 33 bits of precision.Unsigned64 An unsigned integer with fewer than 65 bits of precision.Date A calendar date.DateTime A calendar date and time of day independent of time zone.DateTimeOffset A calendar date and time of day within a specific time zone.Time A time of day and time zone.Text A sequence of characters.Logical A logical flag.Binary A sequence of binary octets.Guid A globally unique identifier 121 Download from Wow! eBook CHAPTER 5  M – THE MODELING LANGUAGE Byte A single binary octet. Collection An unordered group of potentially duplicate values. Entity A collection of labeled values. The Collection Type The collection type is an unordered group of potentially duplicate values. A collection can be constructed as an expression with a beginning brace ({), a type reference, an optional multiplicity (described shortly), and an ending brace (}). So the following examples are all valid collections: • {“NPR”, “ABC”, “CBS”, “NBC”} // a collection of four broadcast network names • {“Red”, “White,” “Blue”} // a collection of three color names • {“Baseball”, “Basketball”, “Soccer”} // a collection of three ball game names • {3.141, 2.718} // the collection of the two transcendental numbers π and e, expressed to a 3-decimal precision • {Integer#8} // a collection of any eight integers • {Unsigned16#1..8} // a collection of one to eight Unsigned16 integers • {Date#4..} // a collection of four or more Date types • {Single*} // a collection of zero or more 32-bit floating point numbers • {Double+} // a collection of one or more 64-bit floating point numbers • Cars : {Car*} // defines the Cars extent as the collection of all values of the Car derived type • {“Red”, 32, { }, “NPR”} // defines a collection with two text values, an integer value, and an empty collection value The last example in the preceding list shows that the elements of a collection do not necessarily have to be of the same type, and that collections can contain other collections. The next to last expression uses the ascription operator (:), (as in, “ascribe this identifier to this type”) to define the Cars extent. I’ll talk about this in the section titled “Extents.” Note that the definition of the collection type said that the collections can have duplicate values. So the collection {1, 2, 3, 1, 1, 3, 4, 98} would conform to an {Integer}#8 definition because it is a collection of eight integers, though with some duplicates. Collections also have no positional or sequential information (unlike lists), so the following expression would be true: {1, 2, 3, 4} == {4, 1, 3, 2}.122 Download from Wow! eBook CHAPTER 5  M – THE MODELING LANGUAGEMultiplicity ConstraintsTable 5-2 shows the different kinds of multiplicity operators that can be used in defining or constraininga collection. Since types are simply collections of conforming values, multiplicity operators areimportant in type definitions.Table 5-2. Multiplicity OperatorsMultiplicity Operator Constraint * Requires zero or more values (allows an empty ...