Comparing Values With java.util.Date
- boolean. A boolean value, either TRUE or FALSE
- int and long. An integer literal is of type long if has a suffix of the ASCII letter L. Otherwise it is of type int.
- floating point. A floating-point literal is of type float if it has a suffix of an ASCII letter F. Otherwise its type is double. Optionally, it can have a suffix of an ASCII letter D. A double or floating point literal can optionally include an exponent suffix of E or e, followed by a signed or unsigned number.
- string. String literals are delimited by single quotation marks. Embedded single-quotation marks are doubled. For example, the character string 'Hello' evaluates to the value Hello, while the character string 'He said, ''Hello''' evaluates to He said, 'Hello'. Embedded newlines are kept as part of the string literal.
- char. A literal is of type char if it is a string literal prefixed by the keyword CHAR, otherwise it is of type string. The CHAR literal for the single-quotation mark character is CHAR '''' (four single quotation marks).
- date. A java.sql.Date object that uses the JDBC format prefixed with the DATE keyword: DATE yyyy-mm-dd. In the Date, yyyy represents the year, mm represents the month, and dd represents the day. The year must be represented by four digits; a two-digit shorthand for the year is not allowed.
- time. A java.sql.Time object that uses the JDBC format (based on a 24-hour clock) prefixed with the TIME keyword: TIME hh:mm:ss. In the Time, hh represents the hours, mm represents the minutes, and ss represents the seconds.
- timestamp. A java.sql.Timestamp object that uses the JDBC format with a TIMESTAMP prefix: TIMESTAMP yyyy-mm-dd hh:mm:ss.fffffffff In the Timestamp, yyyy-mm-dd represents the date, hh:mm:ss represents the time, and fffffffff represents the fractional seconds (up to nine digits).
- NIL. Equivalent alternative of NULL.
- NULL. The same as null in Java.
- UNDEFINED. A special literal that is a valid value for any data type. An UNDEFINED value is the result of accessing an attribute of a null-valued attribute. Note that if you access an attribute that has an explicit value of null, then it is not undefined. For example if a query accesses the attribute address.city and address is null, the result is undefined. If the query accesses address, then the result is not undefined, it is NULL.
You can compare temporal literal values DATE, TIME, and TIMESTAMP with java.util.Date values. There is no literal for java.util.Date in the query language.
The GemFire query processor performs implicit type conversions and promotions under certain cases in order to evaluate expressions that contain different types. The query processor performs binary numeric promotion, method invocation conversion, and temporal type conversion.
Binary Numeric Promotion
- Comparison operators <, <=, >, and >=
- Equality operators = and <>
- Binary numeric promotion widens the
operands in a numeric expression to the widest representation used by any of
the operands. In each expression, the query processor applies the following
rules in the prescribed order until a conversion is made:
- If either operand is of type double, the other is converted to double
- If either operand is of type float, the other is converted to float
- If either operand is of type long, the other is converted to long
- Both operands are converted to type int char
Method Invocation Conversion
Method invocation conversion in the query language follows the same rules as Java method invocation conversion, except that the query language uses runtime types instead of compile time types, and handles null arguments differently than in Java. One aspect of using runtime types is that an argument with a null value has no typing information, and so can be matched with any type parameter. When a null argument is used, if the query processor cannot determine the proper method to invoke based on the non-null arguments, it throws an AmbiguousNameException
Temporal Type Conversion
The temporal types that the query language supports include the Java types java.util.Date , java.sql.Date , java.sql.Time , and java.sql.Timestamp , which are all treated the same and can be compared and used in indexes. When compared with each other, these types are all treated as nanosecond quantities.
Enums are not automatically converted. To use Enum values in query, you must use the toString method of the enum object or use a query bind parameter. See Enum Objects for more information.
Query Evaulation of Float.NaN and Double.NaN
Float.NaN and Double.NaN are not evaluated as primitives; instead, they are compared in the same manner used as the JDK methods Float.compareTo and Double.compareTo. See Double.NaN and Float.NaN Comparisons for more information.