SpirirHost Support Centre: MySQL Reference Manual p.403

<< previous page -- table of contents -- next page >>

Chapter_1

Chapter_2

Chapter_3

Chapter_4

Chapter_5

Return to Table of Contents

Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

Chapter 6: MySQL Language Reference 403 If you retrieve an ENUM in a numeric context, the column value's index is returned. For example, you can retrieve numeric values from an ENUM column like this: mysql> SELECT enum_col+0 FROM tbl_name; If you store a number into an ENUM, the number is treated as an index, and the value stored is the enumeration member with that index. (However, this will not work with LOAD DATA, which treats all input as strings.) It's not advisable to store numbers in an ENUM string because it will make things confusing. ENUM values are sorted according to the order in which the enumeration members were listed in the column specication. (In other words, ENUM values are sorted according to their index numbers.) For example, "a" sorts before "b" for ENUM("a", "b"), but "b" sorts before "a" for ENUM("b", "a"). The empty string sorts before non-empty strings, and NULL values sort before all other enumeration values. If you want to get all possible values for an ENUM column, you should use: SHOW COLUMNS FROM table_name LIKE enum_column_name and parse the ENUM denition in the second col- umn. 6.2.3.4 The SET Type A SET is a string object that can have zero or more values, each of which must be chosen from a list of allowed values specied when the table is created. SET column values that consist of multiple set members are specied with members separated by commas (`,'). A consequence of this is that SET member values cannot themselves contain commas. For example, a column specied as SET("one", "two") NOT NULL can have any of these values: "" "one" "two" "one,two" A SET can have a maximum of 64 dierent members. Starting from 3.23.51 trailing spaces are automatically deleted from SET values when the table is created. MySQL stores SET values numerically, with the low-order bit of the stored value corre- sponding to the rst set member. If you retrieve a SET value in a numeric context, the value retrieved has bits set corresponding to the set members that make up the column value. For example, you can retrieve numeric values from a SET column like this: mysql> SELECT set_col+0 FROM tbl_name; If a number is stored into a SET column, the bits that are set in the binary representation of the number determine the set members in the column value. Suppose a column is specied as SET("a","b","c","d"). Then the members have the following bit values: SET member Decimal value Binary value a 1 0001 b 2 0010 c 4 0100

MySQL Reference Manual

Home
Hosting Plans \| Domain Registration \| About Us \| Contact Us \| Site Map Terms of Use \| Privacy Policy \| Guarantees Merchant Accounts

SpiritHost - web hosting for spiritual and education sites SpiritHit.com - Religious and Spiritual Portal Copyright © 2002 Dyntex Group, Inc. All Rights Reserved

Return to Table of Contents	Back to top

Web Hosting: Manuals & FAQ's

1. Unix-Based Web Hosting
2. Unix Dedicated Servers
3. Windows Dedicated Servers
4. CuteFTP User’s Guide
5. CuteHTML User’s Guide
6. WS_FTP Pro User's Guide
7. Miva Order User's Guide
8. Miva Merchant User's Guide