|
1 | | -<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.49 2001/01/21 22:02:01 petere Exp $ --> |
| 1 | +<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.50 2001/02/05 19:21:45 petere Exp $ --> |
2 | 2 |
|
3 | 3 | <chapter id="functions"> |
4 | 4 | <title>Functions and Operators</title> |
|
185 | 185 | <literal>3</literal>). |
186 | 186 | </para> |
187 | 187 |
|
| 188 | + <para> |
| 189 | + In addition to the comparison operators, the special |
| 190 | + <token>BETWEEN</token> construct is available. |
| 191 | +<synopsis> |
| 192 | +<replaceable>a</replaceable> BETWEEN <replaceable>x</replaceable> AND <replaceable>y</replaceable> |
| 193 | +</synopsis> |
| 194 | + is equivalent to |
| 195 | +<synopsis> |
| 196 | +<replaceable>a</replaceable> >= <replaceable>x</replaceable> AND <replaceable>a</replaceable> <= <replaceable>y</replaceable> |
| 197 | +</synopsis> |
| 198 | + Similarly, |
| 199 | +<synopsis> |
| 200 | +<replaceable>a</replaceable> NOT BETWEEN <replaceable>x</replaceable> AND <replaceable>y</replaceable> |
| 201 | +</synopsis> |
| 202 | + is equivalent to |
| 203 | +<synopsis> |
| 204 | +<replaceable>a</replaceable> < <replaceable>x</replaceable> OR <replaceable>a</replaceable> > <replaceable>y</replaceable> |
| 205 | +</synopsis> |
| 206 | + There is no difference between the two respective forms apart from |
| 207 | + the <acronym>CPU</acronym> cycles required to rewrite the first one |
| 208 | + into the second one internally. |
| 209 | + </para> |
| 210 | + |
188 | 211 | <para> |
189 | 212 | To check whether a value is or is not NULL, use the constructs |
190 | 213 | <synopsis> |
|