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Lua Data Types

Lua has a limited set of data types. The following table shows how eXtremeSQLdata types are represented in Lua:

eXtremeSQL data type Lua data type Comments

char(N), varchar(N) String

TINYINT, SMALLINT, INT, INT(N), UNSIGNED(N), BIGINT Number Note that Lua language does not distinguish integers and floats. All are internally stored as 64-bit double values

FLOAT, REAL, DOUBLE Number

NUMERIC, DOUBLE Number Fixed-point values of type Numeric are converted to floating point double values when passed to a UDF. Note that a UDF return type of a fixed-point type is not supported.

Date, time, timestamp Number Converted to integer value, compatible with os.time()

Binary, varbinary, longvarbinary String

REFERENCE Not supported

BLOB String A blob can not be used as return value for a UDF.

ARRAY Table A table can be created and passed to the UDF. And a table can be returned back.

SEQUENCE Userdata A “handle” to the sequence is passed into UDF as userdata. This handle can be used in functions: seqiter(it), iseq(), iseqn()

eXtremeSQL data type	Lua data type	Comments
char(N), varchar(N)	String
TINYINT, SMALLINT, INT, INT(N), UNSIGNED(N), BIGINT	Number	Note that Lua language does not distinguish integers and floats. All are internally stored as 64-bit double values
FLOAT, REAL, DOUBLE	Number
NUMERIC, DOUBLE	Number	Fixed-point values of type `Numeric` are converted to floating point `double` values when passed to a UDF. Note that a UDF return type of a fixed-point type is not supported.
Date, time, timestamp	Number	Converted to integer value, compatible with `os.time()`
Binary, varbinary, longvarbinary	String
REFERENCE	Not supported
BLOB	String	A `blob` can not be used as return value for a UDF.
ARRAY	Table	A table can be created and passed to the UDF. And a table can be returned back.
SEQUENCE	Userdata	A “handle” to the sequence is passed into UDF as userdata. This handle can be used in functions: `seqiter(it)`, `iseq()`, `iseqn()`