Retrieve data

Each HCL OneDB™ data type can fit in a .NET Framework data type.

The following table shows each HCL OneDB data type, the recommended type to store that data type in, and the .NET Framework data type that it best fits in. The recommended type should be used when accessing data through an IfxDataReader. The best-fit .NET type is the type that an IfxDataAdapter object will use when it fills a DataSet object.

You can use types other than those shown, for example you can use the IfxDataReader.GetString method to get any data type that can be stored in the HCL OneDB database. The types recommended are the most efficient and least likely to change the value.

Table 1. Best-fit types for retrieving HCL OneDB data types
HCL OneDB data type	Recommended type	Best-fit native .NET data type
BIGINT	Int64	Int64
BIGSERIAL	Int64	Int64
BLOB	IfxBlob	Byte[]
BOOLEAN	Boolean	Boolean
BYTE	Byte[]	Byte[]
CHAR	String	String
CHAR(1)	String	String
CLOB	IfxClob	Byte[]
DATE	IfxDateTime	DateTime
DATETIME	IfxDateTime	DateTime
DECIMAL(p<=28) fixed scale	IfxDecimal	Decimal
DECIMAL (p<=28) floating point	IfxDecimal	Double
DECIMAL (p>28)	IfxDecimal	String
DOUBLE	Double	Double
FLOAT	Double	Double
IDSSECURITYLABEL	Int64[]	Int64[]
INTEGER	Int32	Int32
INT8	Int64	Int64
INTERVAL, year-month	IfxMonthSpan	String
INTERVAL, day-fraction	IfxTimeSpan	TimeSpan
LVARCHAR	String	String
MONEY	IfxDecimal	As for Decimal with same precision
NCHAR	String	String
REAL	Float	Float
SERIAL	nt32	Int32
SERIAL8	Int64	Int64
SMALLFLOAT	Float	Float
TEXT	String	String
VARCHAR	String	String

For the format of HCL OneDB data types, DECIMAL, MONEY, DATETIME, and INTERVAL returned using IfxDataReader.GetString method see the section about the Literal Row segment in HCL OneDB Guide to SQL: Syntax.

The ROW and TEXT types and the collection types, LIST, MULTISET, SET, can be mapped to a string literal .NET Core type and accessed with the IfxDataReader.GetString method. The format for the string is documented in the HCL OneDB Guide to SQL: Syntax, in the section about the Literal Row segment.

In order to make the expression of any nested string literals simpler, a leading quotation mark is not returned in the string. A single-quotation mark, rather than a double-quotation mark, is used to begin and end any string literals embedded in the ROW type. This is to avoid confusion if a double-quotation mark might be used as a delimited identifier.