MySQL Questions

1. MySQL - INDEXES? Answer: An index is a data structure that improves the speed of operations on a database table. Indexes, however, reduce the efficiency of INSERT and UPDATE operations on a table. This is because when we insert or update a data value in a table, indexes also need to be modified accordingly. So, they are not always appropriate to use. 2. Types of MySQL Indexes? Answer: Indexes can be defined on single or multiple columns of a MySQL table. The decision to add indexes on a table column(s) depends on the type of data that needs to be searched. MySQL provides the following types of indexes − Simple Index : A simple index is a basic type of index where the values inserted into the column, containing this index, are searched easily. In such case, the column can contain duplicate values or NULL. Unique Index : A Unique index does not allow any duplicate values to be inserted into a table column (where the index is defined on).It can be added to single or multiple columns of a table. Primary Key Index : Primary Key Index is an extension of unique index, as the primary key column must always contain unique values and these values must not be NULL. Fulltext Index : In a database, sometimes you would have to search for a blob of text instead of a record. You can use fulltext index for it. As its name suggests, it is used to make the text searches in a table easier. Descending Index : The descending index is only available in MySQL versions after 8.0. It is simple index used to store data in a reverse order. Using this index, it is easy to search for the latest values inserted into the database table.

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