B.5 SELECT – Restricted

This statement restricts the data returned by comparing the data in the table against the conditions specified in the WHERE clause.

SELECT * FROM tablename WHERE fieldname-expression [AND|OR fieldname-expression]

tablename

The name of the table from which to retrieve data.

fieldname-expression

Can take one of the following forms:

· [NOT] fieldname operator constant

· fieldname IS [NOT] NULL

· fieldname IS [NOT] TRUE

· fieldname IS [NOT] FALSE

· fieldname [NOT] LIKE “string%”

Value	Description
fieldname	The name of a field in the table to use in a comparison operation.
operator	The type of operation performed. Can be one of the following values:
	Operator	Description
	=	Equal*
	>	Greater than
	>=	Greater than or equal
	<	Less than
	<=	Less than or equal
	<>	Not equal*
constant	A numeric string or date, enclosed by quotation marks.
string%	A string constant followed by the percent (%) or asterisk (*) wildcard character. A wildcard character can also be used by itself to match everything. Use a wildcard character only at the end of the string constant.

*. This operator produces an error when used with floating-point data types.

An error results if an SQL statement uses the equal operator (=) or the not equal (<>) operator to compare floating-point data types.

You can use parentheses to group expressions and establish precedence.

The following additional rules apply to the WHERE statement:

When used, no type conversion is done.
BETWEEN is not supported.
IN is not supported.
LIKE only works against varchar data types.
WHERE clauses against unsigned data are not supported.
The varbinary data types are supported only with the IS [NOT] NULL operator.
Floating point comparisons are approximate. Testing for equality against floating point values is not supported and returns an invalid field comparison error.