Chapter 5
|
Supported standards 43
Operator precedence
As expressions become more complex, the order in which the expressions are evaluated becomes important.
This table shows the order in which the operators are evaluated. The operators in the first line are evaluated
first, and so on. Operators in the same line are evaluated left to right in the expression.
The following example shows the importance of precedence:
WHERE salary > 40000 OR hire_date > {01/30/2004} AND dept = 'D101'
Because AND is evaluated first, this query retrieves employees in department D101 hired after January 30,
2004, as well as every employee making more than $40,000, no matter what department or hire date.
To force the clause to be evaluated in a different order, use parentheses to enclose the conditions to be
evaluated first. For example:
WHERE (salary > 40000 OR hire_date > {01/30/2004}) AND dept = 'D101'
retrieves employees in department D101 that either make more than $40,000 or were hired after January 30, 2004.
ODBC Catalog functions
The ODBC client driver supports the following Catalog functions:
1 SQLTables - catalog information is stored and reported as single part names (table name only).
1 SQLColumns
1 SQLColumnPrivileges
1 SQLDescribeCol
1 SQLGetTypeInfo
Precedence Operator
1 Unary '-', Unary '+'
2 ^, **
3 *, /
4 +, -
5 =, <>, <, <=, >, >=, Like, Not Like, Is Null, Is Not Null, Between, In, Exists, Any, All
6 Not
7 AND
8 OR
