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GowthamRaj K
2021-07-29 08:24:26 +05:30
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@@ -678,6 +678,16 @@ There are different types of joins available in SQL −
- Simply put, an index is a pointer to data in a table. - Simply put, an index is a pointer to data in a table.
- An index in a database is very similar to an index in the back of a book. - An index in a database is very similar to an index in the back of a book.
The following guidelines indicate when the use of an index should be reconsidered.
**- Indexes should not be used on small tables.
Tables that have frequent, large batch updates or insert operations.
Indexes should not be used on columns that contain a high number of NULL values.
Columns that are frequently manipulated should not be indexed.
### CREATE INDEX ### CREATE INDEX
CREATE INDEX index_name ON table_name; CREATE INDEX index_name ON table_name;