In SQL, data types are references to Java types, whether they are primitive types or objects.
1 Data Types
The following table shows types by language with its corresponding SQL type, the Java type that represents it, and the possible forms of conversion from other types. Some objects are passed by value and others by referencea in function calls. An object is called comparable if it can be used in relational operators.
| Types of Predefined XSQL | ||||||
|---|---|---|---|---|---|---|
| XSQL type | SQL type | JAVA type | Object type | Comparable | Going through | Alternative conversion from |
| string | CHAR | java.lang.String | BASIC | VALUE | java.lang.Object.toString() | |
| boolean | BOOLEAN | java.lang.Boolean | BASIC | VALUE | java.lang.Object.toString() | |
| smallint | SMALINT | java.lang.Short | BASIC | VALUE | java.lang.Number, java.lang.String | |
| integer | INTEGER | java.lang.Integer | BASIC | VALUE | java.lang.Number, java.lang.String | |
| long | BIGINT | java.lang.Long | BASIC | VALUE | java.lang.Number, java.lang.String | |
| bigint | BIGINT | java.lang.BigInteger | BASIC | VALUE | java.lang.Number, java.lang.String | |
| float | FLOAT | java.lang.Float | BASIC | VALUE | java.lang.Number, java.lang.String | |
| double | DOUBLE | java.lang.Double | BASIC | VALUE | java.lang.Number, java.lang.String | |
| decimal | DECIMAL | java.lang.BigDecimal | BASIC | VALUE | java.lang.Number, java.lang.String | |
| date | DATE | java.util.Date | BASIC | VALUE | parse(java.lang.Object.toString(), "dd-MM-yyyy") | |
| time | TIME | java.sql.Time | BASIC | VALUE | parse(java.lang.Object.toString(), "HH:mm:ss") | |
| timestamp | TIMESTAMP | java.sql.Timestamp | BASIC | VALUE | parse(java.lang.Object.toString(), "dd-MM-yyyy HH:mm:ss") | |
| dateunits | JAVA_OBJECT | xsql.DateUnits | BASIC | VALUE | N/A | |
| byte | BLOB | byte[] | BASIC | REFERENCE | N/A | |
| file | BLOB | java.io.File | BASIC | REFERENCE | N/A | |
| node | JAVA_OBJECT | org.w3c.Node | BASIC | REFERENCE | N/A | |
| element | JAVA_OBJECT | org.w3c.Element | BASIC | REFERENCE | N/A | |
| array | JAVA_OBJECT | java.util.ArrayList | COLLECTION | REFERENCE | N/A | |
| map | JAVA_OBJECT | java.util.HashMap | COLLECTION | REFERENCE | N/A | |
| vtable | JAVA_OBJECT | xsql.VTable | COLLECTION | REFERENCE | N/A | |
| object | JAVA_OBJECT | Specifies any type of object, be it an array, a map, etc. Can be considered a wildcard since it does not exist as a concrete type. | COLLECTION | Depends on the real type. | VALUE OR REFERENCE depending on the real type | No conversion is made |
2 Basic Data Types
A type is referred to as basic when it refers to an individual object, either a number, a string of characters and a byte array or a pointer to a file. In all cases, the object is considered singular.
Note
Collections are not considered byte types even if they are equivalent to a byte [] (array of bytes), nor is a collection a string that represents a char [] (array of characters). The collections shown below are characterized by being vector objects or maps.
Types considered basic include:
- string, refers to character strings.
- smallint, number that works with values in the ranges of java.lang.Short
- integer, number that works with values in the ranges of java.lang.Integer
- long, number that works with values in the ranges of java.lang.Long
- bigint, number that works with values in the ranges of java.math.BigInteger
- float, number that works with values in the ranges of java.lang.Float
- double, number that works with values in the ranges of java.lang.Double
- decimal, number that works with values in the ranges of java.math.BigDecimal
- date, that works with dates as java.util.Date
- time, that works with hours as java.sql.Time
- timestamp, that works with time intervals as java.sql.Timestamp
- dateunits, that indicates temporary periods to be used in arithmetic operations regarding dates or intervals.
- byte, that works with bytes.
- file, that works with pointers to files as java.io.File
- node, that works with objects org.w3c.dom.Node
- element, that works with objects org.w3c.dom.Element
2.1 String
The String type represents an immutable string of characters.
All literals in an XSQL routine such as "abc" are constructed as a string type object.
<string> tag allows us to declare string types contain a set of operators to examine individual characters one by one, search for substrings, extract substrings, transform to uppercase or lowercase, etc.
XSQL language includes operators for the addition and comparison of strings. It also incorporates the evaluation of expressions for equality operators: equal to, not equal to, less than and greater than string types.
2.2 Smallint
The smallint type maps to a java.lang. Short and represents a 16-bit integer. Like other numeric objects, the <number> tag is responsible for the creation of this type of data.
2.3 Integer
The integer type maps to a java.lang. Integer and represents a 32-bit integer. Like other numeric objects, the <numberr> tag is responsible for the creation of this type of data.
2.4 Long
The long type maps to a java.lang. Long and represents a 64-bit integer. Like other numeric objects, the <numberr> tag is responsible for the creation of this type of data.
2.5 BigInt
The bigint type maps to a java.math BigInteger and represents an integer of arbitrary precision. Like other numeric objects, the <number> tag is responsible for the creation of this type of data.
2.6 Float
The float type maps to a java.lang. Float and represents a short floating point number. Like other numeric objects, the <number> tag is responsible for the creation of this type of data.
2.7 Double
The double type maps wiht java.lang. Double and represents a long floating point number. Like the rest of numeric objects, the <number> tag is responsible for the creation of this type of data.
2.8 Decimal
The decimal type maps with java.math. BigDecimal and represents an arbitrary precision number. Like the rest of numeric objects, the <number> tag is responsible for the creation of this type of data.
2.9 Date
The date type maps with a java.util. Date and represents a date in coordinated universal time (CUT).
2.10 Time
The time type maps with a java.sql.time which is a wrapper of the java.util type. Date for SQL time types.
2.11 Timestamp
The timestamp type maps with java.sql.timestamp which is a wrapper of the java.util type. Date for SQL timestamp types.
2.12 Byte
The byte type maps with a java.lang.Byte or byte[] and represents an individual byte object or array of bytes. Generally, byte arrays are used in operations converting files to memory and vice versa.
2.13 File
The file type maps with a java.io. File representing a pointer to a file. In particular, the pointer can refer to conventional files or virtual system XSQL filesystems.
2.14 Node
The node type maps with a org.w3c.dom.Node.
2.15 Element
The element type maps with org.w3c.dom.Element.