Categories:
.NET (357)
C (330)
C++ (183)
CSS (84)
DBA (2)
General (7)
HTML (4)
Java (574)
JavaScript (106)
JSP (66)
Oracle (114)
Perl (46)
Perl (1)
PHP (1)
PL/SQL (1)
RSS (51)
Software QA (13)
SQL Server (1)
Windows (1)
XHTML (173)
Other Resources:
How To Create a Single Index for Multiple Columns
How To Create a Single Index for Multiple Columns? - Oracle DBA FAQ - Managing Oracle Table Indexes
✍: FYIcenter.com
If you know a group of multiple columns will be always used together as search criteria, you should create a single index for that group of columns with the "ON table_name(col1, col2, ...)" clause. Here is an example of one index for two columns:
CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VARCHAR(80) NOT NULL, birth_date DATE NOT NULL, social_number VARCHAR(80) UNIQUE NOT NULL); Table created. CREATE INDEX student_names ON student(first_name,last_name); Index created. SELECT index_name, table_name, uniqueness FROM USER_INDEXES WHERE table_name = 'STUDENT'; INDEX_NAME TABLE_NAME UNIQUENES ----------------------- --------------------- --------- SYS_C004123 STUDENT UNIQUE SYS_C004124 STUDENT UNIQUE STUDENT_NAMES STUDENT NONUNIQUE SELECT index_name, table_name, column_name FROM USER_IND_COLUMNS WHERE table_name = 'STUDENT'; INDEX_NAME TABLE_NAME COLUMN_NAME -------------------- ---------------- ---------------- SYS_C004135 STUDENT ID SYS_C004136 STUDENT SOCIAL_NUMBER STUDENT_NAMES STUDENT FIRST_NAME STUDENT_NAMES STUDENT LAST_NAME
The USER_IND_COLUMNS view confirms that index STUDEND_NAMES has two columns FIRST_NAME and LAST_NAME.
2007-04-27, 4948👍, 0💬
Popular Posts:
What are the five levels in CMMI? There are five levels of the CMM. According to the SEI, Level 1 – ...
How To Select Some Rows from a Table? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If yo...
What is a measure in OLAP ? Measures are the key performance indicator that you want to evaluate. To...
What is ISO? ISO 9000 is a family of standards for quality management systems. ISO 9000 is maintaine...
The following variable is available in file1.c, who can access it? static int average; Answer: all t...