What is the use of database indexing?

[Xena]

I have MySQL Database, and it has thousands of records but the problem is that every record of the database will be listed only it has been entered, I am unable to sort out the database,Can anyone guide me How does a database index work? And what is the use of Database Indexing?

[Pageous]

Put the most unique data element first in the index, the element that has the biggest veriety of values. The index will find the correct page faster. An index is like a set of pointers to specific rows in a table. These pointers are ordered in terms of the column(s) defined by the index, which makes SQL's scans much more efficient - they just look up the pointers to the rows with the relevant data (based on a WHERE or other clause), and jump right to the row(s). Index is sorted by key values, (that need not be the same as those of the table)

[semento]

Indexes are used to find rows with specific column values fast. The larger the table, the more this costs. If you have multiple indexes on one column each, there will be n sets of pointers to the rows - each ordered by the specific column. Without an index, MySQL has to start with the first record and then read through the whole table to find the relevant rows. As I will discuss later, you should choose your index(es) wisely. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data.

[Sachit]

To create a new index, you must own, or have the INDEX object privilege for, the corresponding table. Most MySQL indexes (PRIMARY KEY, UNIQUE, INDEX, and FULLTEXT) are stored in B-trees. Exceptions are that indexes on spatial column types use R-trees, and MEMORY (HEAP) tables support hash indexes. The schema that contains the index must also have a quota for the tablespace intended to contain the index, or the UNLIMITED TABLESPACE system privilege.